#Jupiter with the GRS and io starting a transit

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Jupiter with the GRS and io starting a transit via /r/spaceporn https://ift.tt/37LS7Xu

[dreampoetryvisions]

Jupiter with the GRS and io starting a transit via /r/spaceporn https://ift.tt/37LS7Xu

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Jupiter with the GRS and io starting a transit via /r/spaceporn. Picture posted by /u/damo251.

[astrogeoguy]

The Crown’s Jewels, the First Quarter Moon Meanders through Bright Planets, Jupiter bears Black and Red Spots, and Neptune Kisses a Star!

Above: On Wednesday, September 4 from 9:21 to 11:33 pm EDT, observers in the Americas can watch Io’s shadow transit Jupiter, accompanied by the Great Red Spot, as shown here for 10 pm EDT)

Hello, Late Summer Stargazers!

Here are your Astronomy Skylights for the week of September 1st, 2019 by Chris Vaughan. Feel free to pass this along to your friends and send me your comments, questions, and suggested topics. I repost these emails with photos at http://astrogeoguy.tumblr.com/ where all the old editions are archived. You can also follow me on Twitter as @astrogeoguy! Unless otherwise noted, all times are Eastern Time. Please click this MailChimp link to subscribe to these emails.

I can bring my Digital Starlab inflatable planetarium to your school or other daytime or evening event. Contact me, and we’ll tour the Universe together!

The Moon and Planets

If last week was the best week for skywatchers worldwide, this is the week for lunatics – the lovers of our natural satellite, Luna! Between now and next Sunday, the moon will March across the evening sky worldwide, waxing in phase and visiting two bright planets. Meanwhile, we have a minor meteor shower underway, and we can enjoy summer constellation sights in evening, autumn ones at midnight, and our winter treats during the pre-dawn hours. Here are your Skylights! 

The moon will begin the week as a delicate waxing crescent visible over the western horizon after sunset. Watch for Earthshine - sunlight that has reflected off the seas and white clouds of Earth and is illuminating the unlit portion of the moon’s near side. The bright, white star that you see below the moon (or above it, if you live south of the Equator) on Sunday and Monday evening is Spica, the brightest star in Virgo (the Maiden). Note how the moon moves with respect to that star from one night to the next. 

On Wednesday and Thursday, the now healthy crescent moon will pass through the modest stars of Libra (the Scales). The moon never wanders far from the Ecliptic, the imaginary line that traces the sun’s path through the zodiac constellations. So the moon is usually within those familiar constellations, allowing you to see where they are – even after the moon has moved away from them. 

Thursday will bring the First Quarter Moon phase - when the angle formed by the sun, Earth, and moon forms a right-angle, causing the moon to appear half-illuminated, on its eastern side. (East and west on the moon are opposite to sky directions on Earth.) First quarter moons always rise around noon time, allowing you to see them in the afternoon. Evenings around first quarter are the best ones for viewing the moon in binoculars and backyard telescopes. The topography along the terminator – the pole-to-pole line that divides the lit and dark halves – is being lit by low-angled sunlight which produces breathtaking vistas of bright mountain peaks and crater rims, and the deep black shadows they cast. Moon phases are shared by everyone around the world.

(Above: On Thursday, observers worldwide will see the First Quarter moon near very bright Jupiter, as shown here at 9:30 pm EDT. The following nights, the moon will hop east of Jupiter and then do the same for Saturn.) 

Thursday night will also begin the moon’s dance with the gas giant planets. Look for the moon in the southwestern sky, and positioned less than four finger widths to the right (or 4 degrees to the celestial northwest) of the bright planet Jupiter. The moon and Jupiter will both fit within the field of view of binoculars. If you watch the pair over several hours, starting at dusk, you will see the moon’s orbit carry it closer to the planet. Look for the bright reddish star Antares “the Rival of Mars” twinkling below the moon. That is the heart of Scorpius (the Scorpion). To the west of Antares, three little white stars in a vertical line and each separated by three finger widths from the next one, represent the critter’s claws. Remember that Jupiter will stay with the scorpion after the moon moves away – all autumn, in fact. 

On Friday night, the waxing gibbous (i.e., more than half-full) moon will hop to sit on the east side of Jupiter. Then, on Saturday night, the moon will land immediately above the Teapot-shaped stars of Sagittarius (the Archer), and a palm’s width the right (or celestial west) of Saturn. As with Jupiter, the moon will hop to the other side of Saturn on Sunday night – and the ringed planet will stay near the Teapot for the rest of this year.   

Mercury, Venus, and Mars are out of sight - hidden in the sun’s glare, for now. But the two fast inner planets will bring them into view in the evening sky next week. 

As the sky begins to darken this week, look for the giant planet Jupiter sitting less than a third of the way up the southwestern sky. Hour by hour, Jupiter will sink lower – then set in the west before midnight local time. Jupiter is spending the rest of this year between Ophiuchus (the Serpent-Bearer) and Scorpius (the Scorpion). Normally a planet becomes harder to see when it reaches the southwestern evening sky. But the earlier sunsets and the planet’s brilliance will keep it in view for some time to come. 

On a typical night, even a backyard telescope will show you Jupiter’s two main equatorial stripes and its four Galilean moons - Io, Europa, Callisto, and Ganymede looking like small white dots arranged in a rough line flanking the planet. If you see fewer than four dots, then some of them are in front of Jupiter, or hidden behind it. Good binoculars will show the moons, too! 

From time to time, the small, round, black shadows cast onto Jupiter’s surface by those four Galilean moons become visible in amateur telescopes as they cross (or transit) Jupiter’s disk. On Wednesday, September 4 from 9:21 to 11:33 pm EDT, observers in the Americas can watch Io’s shadow transit Jupiter, accompanied by the Great Red Spot! 

Due to Jupiter’s rapid 10-hour rotation period, the Great Red Spot (or GRS) is only observable from Earth every 2nd or 3rd night, and only during a predictable three-hour window. The GRS will be easiest to see using a medium-sized, or larger, aperture telescope on an evening of good seeing (steady air). If you’d like to see the Great Red Spot in your telescope, it will be crossing the planet on Monday evening from dusk to 11 pm EDT, on Wednesday from 9:20 to 11:30 pm EDT (accompanied by the Great Red Spot), and on Saturday from dusk until 10 pm EDT. 

Yellow-tinted Saturn is prominent in the southern evening sky, too - but it is less bright than Jupiter. The ringed planet will be visible from dusk until about 2 am local time. Saturn’s position in the sky is just to the upper left (or celestial east) of the stars that form the teapot-shaped constellation of Sagittarius (the Archer). To find Saturn, look about 3 fist diameters to the left (east) of Jupiter. The Milky Way is between them. 

Dust off your telescope! Once the sky is dark, even a small telescope will show Saturn's rings and several of its brighter moons, especially Titan! Because Saturn’s axis of rotation is tipped about 27° from vertical (a bit more than Earth’s axis), we can see the top surface of its rings, and its moons can arrange themselves above, below, or to either side of the planet. During this week, Titan will migrate counter-clockwise around Saturn, moving from the upper left of Saturn tonight (Sunday) to below the planet next Sunday. (Remember that your telescope will flip the view around.) 

Tiny, blue Neptune will rise at dusk this week, and then it will climb the eastern sky until it reaches its highest point, due south, at about 1:30 am local time. The planet is among the stars of Aquarius (the Water-Bearer). Recently, Neptune has been sitting just to the left (celestial east) of a medium-bright star named Phi (φ) Aquarii. Neptune is actually moving slowly toward that star and will “kiss” it on Thursday and Friday nights this week, an event that will help you locate dim Neptune.

Astronomers call such an event a conjunction. Being so close together, both the star and Neptune will appear together in the field of view of a telescope. But blue Neptune’s light has been travelling for 4 hours to reach your eye, while the warmly-tinted light of Phi Aquarii has been journeying for 202 years! After this weekend, the distance between the two objects will increase due to Neptune’s eastward orbital motion.

(Above: The path of blue Neptune past the medium-bright stat Phi Aquarii will produce a close conjunction on September 5 and 6. Each yellow dot represents 6 hours of Neptune’s orbital motion this week. They will make an interesting sight in backyard telescopes.)  

Blue-green Uranus will be rising in the east just before 10 pm local time this week; and it will remain visible all night long. Uranus is sitting below (celestial south of) the stars of Aries (the Ram) and is just a palm’s width above the head of Cetus (the Whale). At magnitude 5.8, Uranus is actually bright enough to see in binoculars and small telescopes, under dark skies – and it really does look blue! You can use the three modest stars that form the top of the head of the whale (or sea-monster in some tales) to locate Uranus for months to come – that’s because that distant planet moves so slowly in its orbit. To help you find it, I posted a detailed star chart here.

(Above: The Ice Giant planets are visible in late evening, as shown here at 10:30 pm local time.)  

Aurigids Meteor Shower

A minor meteor shower named the Aurigids is underway. It peaks today (Sunday) and ends next weekend. Look for several of these meteors per hour. They’ll be moving away from the northeastern horizon, where the constellation that gives them their name, Auriga (the Charioteer), rises in late evening. 

The Northern Crown Rests in the West

Corona Borealis (the Northern Crown) can be spotted halfway up the western evening sky in early September. The constellation actually sits about midway along the imaginary line that joins the two bright stars Vega and Arcturus. The earlier autumn sunsets extend our opportunity to explore Corona Borealis. This incomplete circlet of medium-bright stars is roughly 7 degrees across (a generous palm’s width). It is both a constellation and an asterism (an informal star pattern). Corona Borealis’ brightest star Alphecca is a white, A-class star located 75 light-years from the sun. Alphecca’s placement in the constellation is reminiscent of a diamond in a ring. The star’s name derives from the Arabic expression for “broken”, referring to the incomplete ring.

(Above: The distinctive constellation of Corona Borealis, the Northern Crown, sits in the western evening sky - midway between the two bright stars Vega (at top centre) and Arcturus. The sky is shown for 10 pmlocal time this week.)

While the Northern Crown is poor in deep sky objects, it contains several interesting jewels -  double and variable stars. Alphecca itself is an eclipsing binary system that varies in brightness by a tiny amount every 17.36 days, similar to the behavior of the star Algol in Perseus (the Hero). Eruptive variable stars are named for R Coronae Borealis, which is located about three finger widths above (or 3.5 degrees to the celestial northeast of) Alphecca. R Corona Borealis is a hydrogen-deficient and carbon-rich supergiant star. From time to time, it’s usual visual magnitude of 5.8 drops to as little as magnitude 14, possibly due to the formation of opaque carbon dust that blocks visible light, but passes infrared wavelengths. Another star named S Coronae Borealis exhibits the same range of variability, but with a 360-day period. The Blaze Star (T Coronae Borealis) is a cataclysmic variable star, also called a recurrent nova-type. Normally shining between visual magnitude 10.2 and 9.9, on rare occasions it has brightened to magnitude 2 in a period of hours, caused by a nuclear chain reaction and the subsequent explosion.

(Above: The crown’s jewels include the variable stars R, S, and T Coronae Borealis)   

August-September Stargazing Suggestions - Lyra

If you missed last week’s tour of the constellation of Lyra (the Harp), I posted it here. Over the next weeks, we’ll look at some other constellations, too. 

Public Astro-Themed Events

Taking advantage of the moon and other bright objects in the sky this week, the RASC Toronto Centre astronomers will hold their free monthly public City Sky Star Party in Bayview Village Park (steps from the Bayview subway station), starting around 8 pm on the first clear weeknight this week (Tues to Thu only). You don’t need to be an RASC member, or own any equipment, to join them – looks are free! Check here for details, and check the banner on their website home page or Facebook page for the GO or NO-GO decision around 5 pm each day. 

Every Monday evening, York University’s Allan I. Carswell Observatory runs an online star party - broadcasting views from four telescopes/cameras, answering viewer questions, and taking requests! Details are here. On Wednesday nights they offer free public viewing through their rooftop telescopes. If it’s cloudy, the astronomers give tours and presentations. Details are here. 

If the skies are clear on Thursday evening, September 5, local astronomers will set up their telescopes in Old Thornhill Village. This free event starts at 8 pm and everyone is welcome to come out for a look at the Moon, Jupiter and Saturn, and a variety of deep-sky treasures. The viewing location is Thornhill's very own “dark-sky oasis,” the Pomona Meadow - situated north of the cemetery on Charles Lane, and east of the Ukrainian Catholic Church of St. Volodymyr. Park for free at the church and just follow the paved path. The rain or cloud date is Thursday, October 3 at 7:00 pm. Dress warmly, and we’ll see you there! 

Eastern GTA sky watchers are invited to join the RASC Toronto Centre and Durham Skies for solar observing and stargazing at the edge of Lake Ontario in Millennium Square in Pickering on Friday evening, September 6, from 6 pm to 11 pm. Details are here. Before heading out, check the RASCTC home page for a Go/No-Go call in case it's too cloudy to observe. The rain date is Saturday. That same evening, RASC and Durham Skies will be donating a telescope to the Pickering Public Library in a public ceremony. In case of rain or bad weather, the ceremony will be moved to the Pickering Library Auditorium (2nd floor) at 1 The Esplanade. 

If it’s sunny on Saturday morning, September 7 from 10 am to noon, astronomers from the RASC Toronto Centre will be setting up outside the main doors of the Ontario Science Centre for Solar Observing. Come and see the Sun in detail through special equipment designed to view it safely. This is a free event (details here), but parking and admission fees inside the Science Centre will still apply. Check the RASC Toronto Centre website or their Facebook page for the Go or No-Go notification. 

Please note: Due to some filming permits at DDO, some of our events in September have been cancelled. Here’s the updated information… 

The next RASC-hosted Night at the David Dunlap Observatory will be on Saturday, September 21. There will be sky tours in the Skylab planetarium room, space crafts, a tour of the giant 74” telescope, and viewing through the 74” and lawn telescopes (weather permitting). The doors will open at 8:30 pm for a 9 pm start. Attendance is by tickets only, available here. If you are a RASC Toronto Centre member and wish to help us at DDO in the future, please fill out the volunteer form here. And to join RASC Toronto Centre, visit this page. 

This Fall and Winter, spend a Sunday afternoon in the other dome at the David Dunlap Observatory! On Sunday afternoon, October 20, from noon to 4 pm, join me in my Starlab Digital Planetarium for an interactive journey through the Universe. We’ll tour the night sky and see close-up views of galaxies, nebulas, and star clusters, view our Solar System's planets and alien exo-planets, land on the moon, Mars - and the Sun, travel home to Earth from the edge of the Universe, hear indigenous starlore, and watch immersive fulldome movies! Ask me your burning questions, and see the answers in a planetarium setting - or sit back and soak it all in. Sessions run continuously between noon and 4 pm. Ticket-holders may arrive any time during the program. The program is suitable for ages 3 and older, and the Starlab planetarium is wheelchair accessible. For tickets, please use this link.

Keep looking up, and enjoy the sky when you do. I love questions and requests - so, send me some! 

[spiralwizardtowerlibrary]

Jupiter with the GRS and io starting a transit via /r/spaceporn https://ift.tt/37LS7Xu

[spiralwizardtowerlibrarystation]

Jupiter with the GRS and io starting a transit via /r/spaceporn https://ift.tt/37LS7Xu

[astrogeoguy]

The Full Thunder Moon gets Eclipsed, Evening Gas Giant-Gazing, and the 50th Anniversary of Apollo 11 Arrives!

(Above: Features visible on a full moon are labelled on this image by Michael Watson of Toronto. The Apollo Mission landing sites are the red numerals. Apollo 11 was sent to study the dark, bluish basalts of Mare Tranquilitatis.)

Hello, Summer Stargazers!

Here are your Astronomy Skylights for the week of July 14th, 2019 by Chris Vaughan. Feel free to pass this along to your friends and send me your comments, questions, and suggested topics. I repost these emails with photos at http://astrogeoguy.tumblr.com/ where all the old editions are archived. You can also follow me on Twitter as @astrogeoguy! Unless otherwise noted, all times are Eastern Time. Please click this MailChimp link to subscribe to these emails. If you are a teacher or group leader interested joining me on a guided field trip to York University’s Allan I. Carswell Observatory or the David Dunlap Observatory, visit www.astrogeo.ca.

I can bring my Digital Starlab inflatable planetarium to your school or other daytime or evening event. Contact me, and we’ll tour the Universe together!

The Moon and Planets

This week, a big, bright moon will dominate evening skies all over the world – perfect for reminding us to celebrate humankind’s first steps upon it 50 years ago this Saturday, July 20 when Apollo 11 landed on the moon. Besides that, there are plenty of other celestial doings to look at. Here are the Skylights! 

When the bright, nearly full moon rises over the southeastern horizon at 8:30 pm local time on Monday evening, the medium-bright, yellowish planet Saturn will be positioned 2.5 finger widths to the left (celestial east) of it. The pair will cross the sky together during the night and will easily fit within the field of view of your binoculars. If you watch the pair over several hours, starting at dusk, you will see the moon’s orbit carry it closer to the planet and the rotation of the sky lift Saturn above the moon. Observers in eastern Melanesia, southern Polynesia, Easter Island, and central South America will see the moon cover (or occult) Saturn. 

The July full moon will happen at 5 pm EDT on Tuesday. Also known as the “Buck Moon”, “Thunder Moon”, or “Hay Moon”, this one always shines in or near the stars of Sagittarius (the Archer) or Capricornus (the Sea-Goat). When the moon approaches its full phase, all of the regions where the Apollo astronauts explored are illuminated by sunlight. Each of the six crewed Apollo Missions was sent to a different region of the moon in order to carry out experiments and to bring back rock samples that help us determine the age and composition of the moon’s surface. For safety reasons, Apollo 11 was sent to the flat and relatively featureless terrain of Mare Tranquillitatis “Sea of Tranquility”. Later missions landed in more rugged regions with complex geology. Visually, Mare Tranquilitatis is darker and bluer than the other mare – due to a higher Titanium content in the basalt rocks that created it. 

This full moon will also feature a partial lunar eclipse. The northern portion of the moon will pass through the southern edge of Earth’s umbral shadow and become darkened. At greatest eclipse, the moon will be in Sagittarius and positioned 7.5 finger widths east of Saturn. The entire eclipse will be visible from most of Africa, the Middle East, and western India. South America will see the later stages of the eclipse after moonrise, and Australia and Southeast Asia will see the eclipse set in progress. None of the eclipse will be visible from North America. Maximum eclipse occurs near Maputo, Mozambique at 21:30:46 UT. Remember that lunar eclipses are completely safe to watch without eye protection.

(Above: This is the arrangement of the sky that was seen by observers near Toronto at the moment Neil Armstrong was stepping on the moon - at 10:56:15 pm EDT.) 

After Tuesday, the moon will wane in phase and rise later – passing through the stars of Capricornus and then Aquarius (the Water-Bearer) on the coming weekend. Unfortunately, the moon will rise very late on the anniversary date. 

Mars is steadily fading from view as it slips downward towards the evening sun. Your best chance to see it will be low in the north-northwestern sky before about 9:30 pm local time. Thankfully, we’ve got the two big gas giant planets to view in evening this summer. 

The incredibly bright object gleaming in the southeastern evening sky is Jupiter! This week, Jupiter will be visible from dusk to about 3 am local time. Even a backyard telescope can show Jupiter’s two main equatorial stripes and the four Galilean moons named Io, Europa, Callisto, and Ganymede. They always appear in a rough line flanking the planet. If you see fewer than four, then some are either in front of Jupiter, or hidden behind it.

(Above: On Monday, July 15, the waxing gibbous moon will land near Saturn, as shown here for 10:30 pm EDT. Jupiter is off to the west.) 

From time to time, the small, round black shadows cast by the Galilean moons become visible in amateur telescopes as they cross (or transit) Jupiter’s disk. Europa’s shadow will be transiting Jupiter from 9:09 to 11:38 pm EDT on Tuesday with the Great Red Spot, and Io’s shadow will cross on Saturday, July 20 from 8:54 to 11:06 pm EDT. 

Due to Jupiter’s rapid 10-hour rotation period, the Great Red Spot (or GRS) is only observable from Earth every 2nd or 3rd night, and only during a predictable three-hour window. The GRS will be easiest to see using a medium-sized, or larger, aperture telescope on an evening of good seeing (steady air). If you’d like to see the Great Red Spot in your telescope, it will be crossing the planet on Tuesday evening from 8 to 11 pm EDT. More GRS viewing opportunities will occur from 9:45 pm to 12:30 am on Thursday night, and after dusk on Sunday. 

Yellow-tinted Saturn will remain visible all night long during August. Its position in the sky is just to the left (east) of the stars that form the teapot-shaped constellation of Sagittarius (the Archer). Saturn is quite a bit dimmer than Jupiter. To find it, look about 3 fist diameters to the lower left (east) of Jupiter. Dust off your telescope! Once the sky is dark, even a small telescope will show Saturn's rings and several of its brighter moons, especially Titan! Because Saturn’s axis of rotation is tipped about 27° from vertical (a bit more than Earth’s is), we can see the top surface of its rings, and its moons can appear above, below, or to either side of the planet. During this week, Titan will migrate counter-clockwise around Saturn, moving from Saturn’s upper left tonight (Sunday) to below the planet next Sunday. (Remember that your telescope will flip the view around.) 

For night owls, distant and dim, blue Neptune is in the southeastern pre-dawn sky, among the stars of Aquarius (the Water-Bearer). The planet will be rising shortly at about 11:30 pm local time this week. You’ll find the magnitude 7.9 planet sitting a thumb’s width to the left (east) of a medium-bright star named Phi (φ) Aquarii. 

Blue-green Uranus will be rising at about 1 am local time this week. It is sitting below the stars of Aries (the Ram) and is just a palm’s width above the head of Cetus (the Whale). At magnitude 5.8, Uranus is bright enough to see in binoculars. 

(Above: Venus will soon vanish into the pre-dawn twilight. for now you can still look for it low in the ENE, as shown here at 5:30 am local time.)

Similar to Mars, Venus is barely bright enough to see within the pre-dawn twilight sky that surrounds it, but it is sitting very low in the northeast - sinking ever-closer to the rising sun. Venus will be rising at about 5 am local time all week. 

Finally, Pluto reaches peak visibility today – but invisible to backyard telescopes. 

Some Moonlight-Friendly Sights

If you missed last week’s suggestions for objects to look for on moonlit nights, I posted the sky charts here. 

Public Astro-Themed Events

At 7:30 pm on Wednesday, July 17, the RASC Toronto Centre will hold their free monthly Recreational Astronomy Night Meeting at the Ontario Science Centre, and the public are welcome. Talks include The Sky This Month (presented by me), imaging planets while at southern locations, and solar science. These meetings are also streamed live on RASC-TC’s YouTube channel. Check here for details. Parking is free. 

Every Monday evening, York University’s Allan I. Carswell Observatory runs an online star party - broadcasting views from four telescopes/cameras, answering viewer questions, and taking requests! Details are here. On Wednesday nights they offer free public viewing through their rooftop telescopes. If it’s cloudy, the astronomers give tours and presentations. Details are here. 

On Tuesday, July 16 and Thursday, July 18, starting at 11 am, U of T’s AstroTour planetarium show will be a Kids Summer Break Show. Find tickets and details here. 

At 3:30 pm on Tuesday, July 16, the Agincourt Library will present a free public talk by Max King from the University of Toronto’s Astronomy & Astrophysics department entitled Mission to Pluto, From Napkin to New Horizon. Check here for details. 

On Tuesday, July 16, starting at 7 pm, U of T’s AstroTour planetarium show will be Our Musical Universe. Find tickets and details here. 

(Above: One of few photographs of Neil Armstrong on the moon, taken by Buzz Aldrin.)

The 50th Anniversary of humankind’s first steps upon another world is here! Here is a list of the places around town where you can join experts and fellow “lunatics” to honour Apollo 11 this Saturday night, July 20. 

On Tuesday, July 16, starting at 8 pm, York University’s Allan I. Carswell Observatory will celebrate the 50th Anniversary of Apollo 11 with a free film and star-gazing on the Arboretum roof! Details are here. 

Ontario Science Centre: Apollo 11 50th Anniversary on Saturday from 10 am to 10 pm features many moon and space activities and presentations, stargazing – and a Canadian astronaut! Regular admission and parking fees apply, except for the star party. Details are here. 

Aga Khan Museum: Moon Landing Festival on Saturday and Sunday from 12 pm to 10 pm features art, live music, talks, and stargazing. Free! Details are here. 

U of T’s Dunlap Institute: SpaceTime on Saturday from 6:30 to 8:30 pm features all-ages fun, talks, games, and giveaways. Free! Details are here. 

The next RASC Family Night at the David Dunlap Observatory will be on Saturday, July 20. There will be sky tours in the Skylab planetarium room, space crafts, a tour of the giant 74” telescope, and viewing through lawn telescopes (weather permitting). The doors will open at 8:30 pm for a 9 pm start. Attendance is by tickets only, available here. If you are a RASC Toronto Centre member and wish to help us at DDO in the future, please fill out the volunteer form here. And to join RASC Toronto Centre, visit this page.

Keep looking up, and enjoy the sky when you do. I love questions and requests - so, send me some!

[astrogeoguy]

A Morning Moon and a Meteor Shower, Jupiter Cruises Past a Cluster, and Some Southerly Sights!

(Above: This week, Jupiter’s apparent orbital motion will carry it from left to right past a globular star cluster designated NGC 6235. The planet, its moons, and the star cluster will all fit into the field of view (simulated here by the circular view) of a backyard telescope at high power, especially around their closest pairing, which will occur on Saturday night. I’ve flipped the view to match most refracting telescopes.)

Hello, Summer Stargazers!

Here are your Astronomy Skylights for the week of July 21st, 2019 by Chris Vaughan. Feel free to pass this along to your friends and send me your comments, questions, and suggested topics. I repost these emails with photos at http://astrogeoguy.tumblr.com/ where all the old editions are archived. You can also follow me on Twitter as @astrogeoguy! Unless otherwise noted, all times are Eastern Time. Please click this MailChimp link to subscribe to these emails. If you are a teacher or group leader interested joining me on a guided field trip to York University’s Allan I. Carswell Observatory or the David Dunlap Observatory, visit www.astrogeo.ca.

I can bring my Digital Starlab inflatable planetarium to your school or other daytime or evening event. Contact me, and we’ll tour the Universe together!

Southern Delta Aquariids Meteor Shower

The Southern Delta Aquariids meteor shower runs annually from July 21 to August 23. It is caused by the Earth passing through a cloud of tiny particles dropped by a periodic comet – likely Comet 96P/Machholtz and the shower will peak before dawn on Sunday, July 28, but is quite active for a week surrounding that date. This shower commonly generates 15-20 meteors per hour at the peak, but is best seen from the southern tropics, where the shower’s radiant, in Aquarius, is positioned higher in the sky. The waning crescent moon on the weekend should not adversely affect the shower very much. 

To increase your chances of seeing meteors, find a dark location with lots of sky, preferably away from light polluted skies, and just look up with your unaided eyes. Binoculars and telescopes are not useful for meteors because their fields of view are too narrow to fit the streaks of meteor light. Don’t watch the radiant. Any meteors near there will have very short trails because they are travelling towards you. Try not to look at your phone’s bright screen – it’ll ruin your night vision. And keep your eyes heavenward, even while you are chatting with companions. Happy hunting!

(Above: The Southern Delta Aquariids Meteor Shower will peak on the coming weekend, July 27-28. The best time for viewing will be before dawn, when the radiant will be higher. The waning crescent moon will not interfere with your hunt.) 

The Moon and Planets

The rest of July will bring us dark evening skies worldwide. That’s because the moon will be rising after midnight and waning in phase and brightness. So grab your bug spray and binoculars, or dust off the old telescope, and set up in a spot with a low and open southern horizon. I’ll tour you through the scorpion, the teapot, and the shield in this week’s Skylights! 

Tonight, the waning gibbous moon (i.e., more than half illuminated) will rise at about midnight local time. For the rest of the week, the moon will shift eastward and wane in phase while it slides towards next week’s meeting with the sun. The moon will be rising later every night, but the night-to-night difference will be much less than the usual 40 to 50 minutes. That’s because the angle between the eastern horizon and the moon’s orbit is smaller at this time of the year.

From Tuesday to Saturday before dawn, the moon’s orbit will carry it just above Cetus (the Whale), flying like a drone from the beast’s tail to his head. On Friday morning, the pretty crescent moon will sit about two finger widths to the upper left of the main belt asteroid Vesta. Look for a medium-bright star named Lambda Ceti sitting about four finger widths to the right of the moon. Vesta will be located a small distance below, and about halfway along, a line joining the moon and that star. Vesta will be visible as a little pinpoint in binoculars and telescopes. 

(Above: As shown here for Friday, July 26 at 4 am local time, the waning moon will be positioned near the major asteroid Vesta. The shallow angle that the ecliptic (yellow) and the moon’s orbit (red) make with the eastern horizon will cause the moon to rise only about 20 minutes later on each consecutive morning.)

On Saturday morning, the crescent moon will land a palm’s width to the upper right (celestial west) of the big triangle of stars that form Taurus the Bull’s face. People in Asia and Australia can see the moon pass directly through those stars, including the bright, orange star Aldebaran, which marks the bull’s angry southern eye. When skywatchers in the Americas see the moon again on Sunday morning, it will be positioned to the lower left (celestial east) of Aldebaran. 

Keep an eye out for the moon in the morning daytime sky this week. On Wednesday it will reach its last quarter phase, when its western half is illuminated. Last quarter moons always rise around midnight and remain visible in the southern sky all morning. They are positioned ahead of the Earth in our trip around the sun. About 3½ hours later, Earth will occupy that same location in space. 

The planets are spread along the Ecliptic (which closely expresses the plane of our Solar System) from sunset to sunrise. Reddish Mars has been steadily fading from view as it slips downward towards the evening sun. Your best chance to see Mars is to look low in the north-northwestern sky for a short time after 9 pm local time. 

(Above: Every days Mars is sinking lower into the western evening sunset, as shown here at 9:15 pm local time.)

Jupiter is the extremely bright, white object shining in the southern evening sky. This week, Jupiter will be visible from dusk until almost 3 am local time. Even a backyard telescope can show Jupiter’s two main equatorial stripes and the four Galilean moons named Io, Europa, Callisto, and Ganymede. The moons always form a rough line flanking the planet. If you see fewer than four, then some are either in front of Jupiter or hidden behind it. 

Jupiter will do something interesting this week, and then it will repeat it a month from now! On the evenings surrounding Friday, July 26, Jupiter’s orbital motion will carry it close past a globular star cluster designated NGC 6235, which is located in the southern sky in the constellation of Ophiuchus (the Serpent-Bearer). At closest approach on July 26, the bright planet will sit only 4 arc-minutes above the cluster. (For comparison purposes, the full moon is 30 arc-minutes across.) You can start looking for the cluster starting tonight. It will be located to Jupiter’s right (celestial west), but your telescope will flip the directions around. 

That star cluster is located about 38,000 light-years away, while Jupiter will only be 38 light-minutes from Earth! Both objects will fit within the field of view of a backyard telescope at medium power. To better see the dim, fuzzy globular cluster, try placing the bright planet just outside your field of view. Binoculars might work, too – if your sky is very dark! 

From time to time, the small, round black shadows cast by the Galilean moons become visible in amateur telescopes as they cross (or transit) Jupiter’s disk. On Tuesday night, Europa’s small shadow will be transiting the northern part of Jupiter from 11:45 pm to 2 am EDT. On Wednesday night, Ganymede’s larger shadow will be transiting the northern part of Jupiter from 11:30 pm to 1:45 am EDT. On Saturday, July 27, Io’s mall shadow will cross from 10:50 pm to 1 am EDT, with the Great Red Spot joining the fun after 11:45 pm.

(Above: On Tuesday night, Europa’s small shadow will be transiting the northern part of Jupiter from 11:45 pm to 2 am EDT, as shown here at 11:55 pm EDT. Your telescope will likely flip and/or mirror the view shown here.) 

Speaking of the spot, due to Jupiter’s rapid 10-hour rotation period, the Great Red Spot (or GRS) is only observable from Earth every 2nd or 3rd night, and only during a predictable three-hour window. The GRS will be easiest to see using a medium-sized, or larger, aperture telescope on an evening of good seeing (steady air). If you’d like to see the Great Red Spot in your telescope, it will be crossing the planet on Tuesday evening from 8:30 to 11:30 pm EDT and on Thursday night from 10:15 pm to 1:15 am EDT. 

(Above: Jupiter events for the next month. Blue times are Galilean Moon shadow transits. Red times are Great Red Spot appearances. The actual viewing window spans about 90 minutes before and after those times.) 

Yellow-tinted Saturn will remain visible all night long this month. Its position in the sky is just to the upper left (celestial east) of the stars that form the teapot-shaped constellation of Sagittarius (the Archer). Saturn is quite a bit dimmer than Jupiter. To find it, look about 3 fist diameters to the lower left (east) of Jupiter. Dust off your telescope! Once the sky is dark, even a small telescope will show Saturn's rings and several of its brighter moons, especially Titan! Because Saturn’s axis of rotation is tipped about 27° from vertical (a bit more than Earth’s axis), we can see the top surface of its rings, and its moons can appear above, below, or to either side of the planet. During this week, Titan will migrate counter-clockwise around Saturn, moving from below Saturn tonight (Sunday) to the upper right the planet next Sunday. (Remember that your telescope will flip the view around.) 

For night owls, distant and dim, blue Neptune is in the southeastern pre-dawn sky, among the stars of Aquarius (the Water-Bearer). The planet will be rising before 10:30 pm local time this week. You’ll find the magnitude 7.9 Neptune sitting a thumb’s width to the left (east) of a medium-bright star named Phi (φ) Aquarii. 

(Above: The two Ice Giant planets Uranus and Neptune are visible after late evening, as shown here at 1 am local time.)

Blue-green Uranus will be rising at about midnight local time this week. It is sitting below the stars of Aries (the Ram) and is just a palm’s width above the head of Cetus (the Whale). At magnitude 5.8, Uranus is bright enough to see in binoculars under dark skies.

In a similar situation to Mars, Venus is barely bright enough to see within the pre-dawn twilight sky that surrounds it. It is sitting very low in the northeastern sky - sinking ever-closer to the rising sun. Venus will be rising at about 5:30 am local time all week. By the end of the week, Mercury will climb over the horizon to join Venus. The swift innermost planet will become easier to see next week.

(Above: Towards the end of this week, Mercury will ascend to sit to the right of descending Venus, both low in the eastern pre-dawn sky, as shown here for 5:40 am local time. Mercury is just beginning a good period of visibility.)  

Touring the Dark July Southern Sky

With the moon rising after midnight and waning in phase and brightness, let’s grab bug spray and binoculars, or dust off the old telescope, and set up in a spot with a low and open southern horizon – for a tour through the scorpion, the teapot, and the shield! 

Once it’s getting nice and dark, face south and look for the Milky Way rising from the southern horizon between Jupiter and Saturn. (Those two planets will only be embracing the Milky Way this summer. They’ll move east of it next year.) Due to haziness near the horizon, and more of Earth’s intervening atmosphere, The Milky Way will be easier to see higher in the sky, where it passes directly through Cygnus (the Swan). By midnight local time, the great swan will be nearly overhead. The rest of the Milky Way will descend to the northeast. It thins as it passes through the “W” of Cassiopeia (the Queen) and Perseus (the Hero) because that area represents the outer edge of our galaxy’s disk. 

Looking due south again - in late July, the distinctive constellation of Scorpius (the Scorpion) reaches its peak elevation over the southern horizon after dusk. Jupiter is spending this year in the sky just northeast of that constellation’s brightest star, orange-tinted Antares, the “Rival of Mars”. Three white, medium-bright stars aligned in a roughly vertical line to the west of Antares mark the creature’s claws today – however the major stars of neighboring Libra (the Scales) used to take that role. The rest of the scorpion extends to the south, curling eastward into the Milky Way, and terminating in a bright double star named Shaula, which marks the poisonous stinger. Observers above mid-northern latitudes will struggle to see the southerly stars of the constellation. For Moana fans, the Maori people of New Zealand consider those same stars to represent Maui’s fish hook pulling the Milky Way up every night!

(Above: In late July and early August annually, the Milky Way appears to rise from the southern horizon, like steam from the Teapot-shaped constellation of Sagittarius, the Archer. The southern sky, shown here at 10:30 pm local time, is riddled with interesting deep sky objects visible in binoculars and backyard telescopes when the sky is dark. Each coloured symbol represents a good target. Dotted circles are open star clusters, circles with crosshairs are globular clusters, and green symbols are nebulas.)

For contrast with cool, reddish Antares, look at the two hot, white stars, both named Al Niyat, that flank the red supergiant. Magnitude 3.1 Al Niyat I (also known as Sigma Scorpii) is located 2 finger widths to the upper right of Antares. It is a B1-class star with a surface temperature of 36,200 K. Magnitude 2.8 Al Niyat II is located 2.25 degrees to the lower left of Antares. Also known as Tau Scorpii, it is a B0-class star with a surface temperature of 30,000 K. At 734 light-years from the sun, Al Niyat I is nearly twice as far away as Al Niyat II. Use binoculars to find a fuzzy patch that is sitting just a finger’s width to Antares’ lower right. It is a globular star cluster named Messier 4. 

Late July evenings bring us one of the best asterisms in the sky, the Teapot in Sagittarius (the Archer). This informal star pattern features a flat bottom formed by the stars Ascella on the left and Kaus Australis on the right, a triangular pointed spout pointing right, marked by the star Alnasl, and a pointed lid marked by the star Kaus Borealis. The stars Nunki and Tau Sagittarii form its handle. The asterism is low in the sky, but it reaches maximum height above the southern horizon around midnight local time, when it will look as if it’s serving its hot beverage – with the steam rising as the Milky Way. By the way – the centre of our galaxy is located just 4.5 finger widths to the upper right of Alnasl! 

(Above: The bright planets Jupiter and Saturn are spanning the Milky Way this summer, as shown here at 10:30 pm local time this week. Scorpius, the Scorpion sits to the right (celestial west) of Sagittarius. Small Scutum, the Shield, is above Sagittarius.)

Next, use your binoculars to explore the rich star fields and nebulae sprinkled along the Milky Way above Sagittarius. The bright star clusters known as Ptolemy’s Cluster (also designated Messier 7), the Sagittarius Star Cloud (Messier 24), and Messier 25 will appear as compact, bright, white clouds in binoculars. You can also look for the bright knots of nebulosity comprising the Lagoon Nebula (Messier 8), the Omega / Swan Nebula (Messier 17), and the Eagle Nebula (Messier 16). Higher up, you’ll discover more good clusters, including Messier 39 and Messier 29 in Cygnus, Caldwell 16 in Lacerta (the Lizard), the Wild Duck cluster (Messier 11) and Messier 26 in Scutum (the Shield). Use your backyard telescope for a closer look! 

Scutum (the Shield) was created by Johannes Hevelius in 1683 by taking some of the stars from next-door Aquila (the Eagle). The small constellation (84th out of 88 by area) occupies some prime celestial real estate along the summertime Milky Way. Scutum, which reaches its highest position over the southern horizon at midnight local time in late July, has a background of rich star fields, which are overlain by some fine open star clusters, including the aforementioned Wild Duck Cluster. Use binoculars to trace out the dim stars that form the constellation and then follow up with your telescope. 

Public Astro-Themed Events

Every Monday evening, York University’s Allan I. Carswell Observatory runs an online star party - broadcasting views from four telescopes/cameras, answering viewer questions, and taking requests! Details are here. On Wednesday nights they offer free public viewing through their rooftop telescopes. If it’s cloudy, the astronomers give tours and presentations. Details are here. 

On Tuesday, July 23, starting at 7 pm, U of T’s AstroTour planetarium show will be Grand Tour of the Cosmos. Find tickets and details here. 

On Thursday, July 25, starting at 7 pm, U of T’s AstroTour planetarium show will be The Life and Death of Stars. Find tickets and details here. 

The next RASC Family Night at the David Dunlap Observatory will be on Saturday, August 10. There will be sky tours in the Skylab planetarium room, space crafts, a tour of the giant 74” telescope, and viewing through lawn telescopes (weather permitting). The doors will open at 8:30 pm for a 9 pm start. Attendance is by tickets only, available here. If you are a RASC Toronto Centre member and wish to help us at DDO in the future, please fill out the volunteer form here. And to join RASC Toronto Centre, visit this page.

Keep looking up, and enjoy the sky when you do. I love questions and requests - so, send me some!

[astrogeoguy]

Lovely Luna in Evening, Saturn Shines at Maximum, and Moonlight-Friendly Sights!

(Above: Look - a donut! The Ring Nebula in Lyra, imaged by Ron Brecher of Guelph, Ontario on July 25, 2012. His other excellent images are found at  http://astrodoc.ca/ )

Hello, Summer Stargazers!

Here are your Astronomy Skylights for the week of July 7th, 2019 by Chris Vaughan. Feel free to pass this along to your friends and send me your comments, questions, and suggested topics. I repost these emails with photos at http://astrogeoguy.tumblr.com/ where all the old editions are archived. You can also follow me on Twitter as @astrogeoguy! Unless otherwise noted, all times are Eastern Time. Please click this MailChimp link to subscribe to these emails. If you are a teacher or group leader interested joining me on a guided field trip to York University’s Allan I. Carswell Observatory or the David Dunlap Observatory, visit www.astrogeo.ca.

I can bring my Digital Starlab inflatable planetarium to your school or other daytime or evening event. Contact me, and we’ll tour the Universe together!

The Moon and Planets

This is the week of the lunar month when skywatchers worldwide can enjoy the moon in the early evening sky - just ahead of next week’s 50th anniversary of Apollo 11. And, two more planets will reach opposition and maximum visibility this week. Here are the Skylights!

(Above: The moon at First Quarter, imaged by Michael Watson of Toronto in spring, 2015. Michael’s amazing photos can be viewed on his Flickr page here.) 

Tonight (Sunday) the moon will begin the week as a pretty waxing crescent in the western, early evening sky on the border between Virgo (the Maiden) and Leo (the Lion). On Tuesday morning, the Earth-orbiting moon will reach a 90 degree angle from the sun - setting up its First Quarter phase, when it appears half-illuminated from Earth. We call this phase “first quarter” because the moon has completed one-quarter of the trip around Earth. 

First quarter moons rise around noon and set around midnight. The evenings surrounding this lunar phase are the best times to look at the moon under magnification. As the sun slowly rises over the moon’s eastern horizon (which takes a week!), its steeply slanted rays of light cast deep, black shadows to the west of every elevated feature – mountains, crater rims, boulders, and even fault lines. Every hour, and every night, the zone alongside the terminator, the pole-to-pole boundary dividing the lit and dark hemispheres, creeps west - revealing new breathtaking vistas. 

On Tuesday night, the moon will take up a position above (celestial north of) the very bright, white star Spica in Virgo. Over the course of several hours, you can watch the moon’s orbital motion carry it eastwards of that star. That’s toward the left for Northern Hemisphere observers, and vice versa. 

On Thursday and Friday night, the waxing gibbous (which means “more than half-illuminated”) moon will visit Libra (the Scales) and then land above the up-down row of three little white stars that mark the claws of Scorpius (the Scorpion). 

In the southern sky on Saturday evening, the waxing gibbous moon will land about three finger widths to the left (east) of the bright planet Jupiter. If you watch the moon and Jupiter over several hours, starting at dusk, you will see the moon’s orbit carry it farther from the planet, while the rotation of the sky will lift the moon above Jupiter.

(Above: The bright gas giant planets continue to dominate the southern evening sky. On Saturday, July 13, the bright, waxing gibbous moon will land near Jupiter, as shown here for 10 pm local time.) 

For about an hour after sunset on the Sunday evening, Mercury’s orbital motion downwards towards the sun will bring it less than 4 finger widths to the lower left (south) of slightly brighter Mars. The two dim planets will be very low in the north-northwestern twilit sky. Take care that the sun has completely disappeared below the horizon before attempting to search for them with binoculars or telescopes. The best time to look for Mercury falls between 9:30 and 9:45 pm local time. Mars sets nearly 30 minutes later, so you’ll have more time to look for it. Observers closer to the Equator will have a better chance to see the two planets – due to a darker sky after sunset. Mercury will drop too low to see after mid-week.

(Above: Mars and Mercury can be spotted with difficulty, low in the north-northwestern sky after sunset early this week, as shown here at 9:40 pm local time. Mercury is following its orbit downward, toward the sun.)  

That incredibly bright object that you’ve been seeing in the southeastern evening sky recently is Jupiter! This week, Jupiter will be visible from dusk to almost 4 am local time. Even a backyard telescope can show Jupiter’s saucy equatorial stripes and the four Galilean moons named Io, Europa, Callisto, and Ganymede. They always appear in a rough line flanking the planet. If you see fewer than four, then some are either in front of Jupiter, or hidden behind it. 

From time to time, the small, round black shadows cast by the Galilean moons become visible in amateur telescopes as they cross (or transit) Jupiter’s disk. Io’s shadow will transit Jupiter after midnight on Thursday (i.e., Friday morning) from 12:31 am to 2:43 am EDT. 

Due to Jupiter’s rapid 10-hour rotation period, the Great Red Spot (or GRS) is only observable from Earth every 2nd or 3rd night, and only during a predictable three-hour window. The GRS will be easiest to see using a medium-sized, or larger, aperture telescope on an evening of good seeing (steady air). If you’d like to see the Great Red Spot in your telescope, it will be crossing the planet starting late on Monday evening (from 10:15 pm until 2:15 am EDT). More GRS viewing opportunities will occur after dusk on Tuesday and Thursday, and on Saturday night from 10:15 pm to 1:30 am EDT. 

On the afternoon of Tuesday, July 9, Earth’s orbit will carry us between Saturn and the sun. Sitting opposite the sun in the sky on that date, Saturn will rise at sunset and arrive at its minimum separation from Earth of 9.0 Astronomical Units (an AU is the average sun-Earth distance). That’s 1.351 billion km, or 75 light-minutes! Saturn will shine at a peak brightness for the year (magnitude +0.05) and exhibit an apparent disk diameter of 18.4 arc-seconds. The rings, which will be getting narrower every year until the spring of 2025, will subtend 42.86 arc-seconds. (For comparison, the full moon is 1,800 arc-seconds across.) Don’t fret if Tuesday is cloudy. Saturn will look nearly as good for several days.

(Above: Saturn will reach peak visibility for 2019 on Tuesday, as shown here at 10:30 pm EDT. Look in the southeastern sky after dusk, about 30 degrees to the lower left of Jupiter.)  

Yellow-tinted Saturn will remain visible all night long. Its position in the sky is just to the left (east) of the stars that form the teapot-shaped constellation of Sagittarius (the Archer). Saturn is quite a bit dimmer than Jupiter. To find it, look about 3 fist diameters to the lower left (east) of Jupiter. Dust off your telescope! Once the sky is dark, even a small telescope will show Saturn's rings and several of its brighter moons, especially Titan! Because Saturn’s axis of rotation is tipped about 27° from vertical (a bit more than Earth’s is), we can see the top surface of its rings, and its moons can appear above, below, or to either side of the planet. During this week, Titan will migrate counter-clockwise around Saturn, moving from Saturn’s right tonight (Sunday) to the upper left of the planet next Sunday. (Remember that your telescope will flip the view around.) 

For night owls, distant and dim, blue Neptune is in the southeastern pre-dawn sky, among the stars of Aquarius (the Water-Bearer). The planet will be rising shortly before midnight local time this week. You’ll find the magnitude 7.9 planet sitting a thumb’s width to the left (east) of a medium-bright star named Phi (φ) Aquarii. 

Blue-green Uranus will be rising at about 1:30 am local time this week. It is sitting below the stars of Aries (the Ram) and is just a palm’s width above the head of Cetus. At magnitude 5.8, Uranus is bright enough to see in binoculars. 

Venus is bright enough to see within the pre-dawn twilight sky that surrounds it, but it is sitting very low in the northeast - sinking ever-closer to the rising sun. Venus will be rising at about 5 am local time all week. 

But wait, there’s more! On Sunday, July 14, the dim and distant dwarf planet Pluto will also reach opposition. (After all, it IS sitting near Saturn this year.) On that date, Pluto will be the closest to Earth (4.91 billion km, or 273 light-minutes) and reach its greatest visual magnitude (+14.2) for 2019. Pluto will rise in the east at sunset and reach its highest elevation, over the southern horizon, at 1:20 am local time. While Pluto is far too dim to see in amateur-grade telescopes, an astronomy app can show you where it is compared to the brighter nearby stars. Even if you can’t see it directly, you will know that Pluto is there. 

Some Moonlight-Friendly Sights

While the moon will brighten evening skies all over the world this week, there are still plenty of sights to see.  

Stars shine with a colouration that is produced by their surface temperatures, and this is captured in their spectral classification. The three bright stars of the Summer Triangle, namely Deneb, Vega, and Altair, are all A-class stars that appear blue-white to the eye and have surface temperatures in the range of 7,500 to 10,000 K. High in the southwestern sky, orange Arcturus is a K-class giant star with a temperature of only 4,300 K. Finally, reddish Antares, the heart of Scorpius, is an old M-class star with a surface temperature of 3,500 K. By comparing these stars colors’ to other stars, you can estimate those stars’ temperatures. The classification letters, from hottest to coolest are: OBAFGKM. Can you think up a mnemonic phrase to remember the order? I have one.

(Above: The bright stars of summer shine with different colours. Deneb, Vega, and Altair are hot white, medium-hot Arcturus is orange, and cooler Antares is closer to reddish. The sky is shown for early July at 10 pm local time.)  

The constellation of Lyra (the Harp) is positioned high overhead in late evening in early July. This constellation features a coffee and a donut! Keen eyes might reveal that the star Epsilon Lyrae, located just one finger’s width to the left (east) of the bright star Vega (Alpha Lyrae), is a double star. Binoculars or a small telescope will certainly show the pair. Examining Epsilon at high magnification will reveal that each of the stars is itself a double – hence its nick-name, “the double-double”. To see the donut, aim your telescope midway between the stars Sulafat and Sheliak, which form the southern end of Lyra’s parallelogram. Messier 57, also known as the Ring Nebula, will appear as a faint grey ring. Higher magnification works well on this planetary nebula – which is the corpse of a star that had a similar mass to our sun.

(Above: The constellation of Lyra, the Harp features summertime’s brightest star, Vega. It also contains a coffee and a donut - the double double-star Epsilon Lyrae and the Ring Nebula, respectively.)  

Mid-July evenings bring us one of the best asterisms in the sky, the Teapot in Sagittarius (the Archer). This informal star pattern features a flat bottom formed by the stars Ascella on the east and Kaus Australis on the west, a triangular pointed spout pointing west, marked by the star Alnasl, and a pointed lid marked by the star Kaus Borealis. The stars Nunki and Tau Sagittarii form its handle. The asterism reaches maximum height above the southern horizon around midnight, when it will look as if it’s serving its hot beverage – with the steam rising as the Milky Way! 

(Above: The stars of Sagittarius form a quaint Teapot-shaper asterism. The Milky Way rises like steam from its spout, as shown here at 11 pm local time in early July.)

The Summer Triangle

If you missed last week’s note about the Summer Triangle asterism, which shines high in the eastern sky every July, I posted it here. 

Public Astro-Themed Events

Taking advantage of the moon and other bright objects in the sky this week, the RASC Toronto Centre astronomers will hold their free monthly public City Sky Star Party in Bayview Village Park (steps from the Bayview subway station), starting around 8 pm on the first clear weeknight this week (Mon to Thu only). You don’t need to be an RASC member, or own any equipment, to join them – looks are free! Check here for details, and check the banner on their website home page or Facebook page for the GO or NO-GO decision around 5 pm each day. 

Every Monday evening, York University’s Allan I. Carswell Observatory runs an online star party - broadcasting views from four telescopes/cameras, answering viewer questions, and taking requests! Details are here. On Wednesday nights they offer free public viewing through their rooftop telescopes. If it’s cloudy, the astronomers give tours and presentations. Details are here. 

On Tuesday, July 9, starting at 7 pm, U of T’s AstroTour planetarium show will be Our Musical Universe. Find tickets and details here. 

Weather permitting, on Tuesday, July 9 from 9 to 10:30 pm, astronomers from RASC – Mississauga will hold a free public star party at the Riverwood Conservancy, 4300 Riverwood Park Lane, Mississauga. Details are here. 

On Thursday, July 11, starting at 7 pm, U of T’s AstroTour will present their planetarium show Grand Tour of the Cosmos. Tickets and details are here. 

At 2 pm on Thursday, July 11, the Cliffcrest Library will present a free public talk by Dr. John Percy, Professor Emeritus at the University of Toronto, in Astronomy & Astrophysics and in Science Education entitled The Amazing Universe. Check here for details. 

If it’s sunny on Saturday morning, July 13 from 10 am to noon, astronomers from the RASC Toronto Centre will be setting up outside the main doors of the Ontario Science Centre for Solar Observing. Come and see the Sun in detail through special equipment designed to view it safely. This is a free event (details here), but parking and admission fees inside the Science Centre will still apply. Check the RASC Toronto Centre website or their Facebook page for the Go or No-Go notification. 

The next RASC Family Night at the David Dunlap Observatory will be on Saturday, July 13. There will be sky tours in the Skylab planetarium room, space crafts, a tour of the giant 74” telescope, and viewing through lawn telescopes (weather permitting). The doors will open at 8:30 pm for a 9 pm start. Attendance is by tickets only, available here. If you are a RASC Toronto Centre member and wish to help us at DDO in the future, please fill out the volunteer form here. And to join RASC Toronto Centre, visit this page. 

Keep looking up, and enjoy the sky when you do. I love questions and requests - so, send me some!

[astrogeoguy]

Meteors Mount, Gas Giants in Evening, and Touring the Triangle and Celestial Critters!

(Above: Albireo is the beautiful double star that marks the head of Cygnus the Swan!)

Hello, Summer Stargazers! 

Here are your Astronomy Skylights for the week of July 28th, 2019 by Chris Vaughan. Feel free to pass this along to your friends and send me your comments, questions, and suggested topics. I repost these emails with photos at http://astrogeoguy.tumblr.com/ where all the old editions are archived. You can also follow me on Twitter as @astrogeoguy! Unless otherwise noted, all times are Eastern Time. Please click this MailChimp link to subscribe to these emails. 

I can bring my Digital Starlab inflatable planetarium to your school or other daytime or evening event. Contact me, and we’ll tour the Universe together! 

Meteor Shower Update

The Southern Delta Aquariids meteor shower runs annually from July 21 to August 23. It is caused by the Earth passing through a cloud of tiny particles dropped by a periodic comet – likely Comet 96P/Machholtz. The shower peaked before dawn this morning (Sunday, July 28), but is quite active for a week surrounding that date. This shower commonly generates 15-20 meteors per hour at the peak, but is best seen from the southern tropics, where the shower’s radiant, in Aquarius (the Water-Bearer), is positioned higher in the sky. The waning crescent moon on the weekend should not adversely affect the shower very much. 

The prolific Perseid Meteor Shower runs from July 13 through August 26, so keep an eye out for a few of them this week. The moon will spoils the show on the peak nights of August 12/13, so take advantage of the darker skies this week. 

To increase your chances of seeing any meteors, find a dark location with lots of sky, preferably away from light polluted skies, and just look up with your unaided eyes. Binoculars and telescopes are not useful for meteors because their fields of view are too narrow to fit the streaks of meteor light. Don’t watch the radiant. Any meteors near there will have very short trails because they are travelling towards you. Try not to look at your phone’s bright screen – it’ll ruin your night vision. And keep your eyes heavenward, even while you are chatting with companions. I’ll write more about meteors in the coming weeks. For now, happy hunting! 

The Moon and Planets

Keep that telescope handy - the first half of this week will feature dark evening skies worldwide. Late on Wednesday, the moon will pass the sun - giving us a second new moon in July, and then our natural satellite will return to grace the western evening sky after sunset to end the week. Here are this week’s Skylights! 

If you are out under the stars before dawn on Monday, you’ll see a pretty crescent moon in the eastern sky, between the toes of Gemini (the Twins) and the upraised club of Orion (the Hunter). Yes – those winter constellations will return to view before we know it! On Tuesday morning, the moon will be lower, and closer to the sun. 

The moon will first return to view, positioned low over the northwestern horizon, shortly after sunset on Thursday evening. For the rest of the week, the moon’s delicate crescent will grow and the moon will set later – passing through the stars of Leo (the Lion) and landing a few finger widths to the right (celestial west) of the medium-bright star Porrima in Virgo (the Maiden) on Sunday evening. Viewed in a backyard telescope, Porrima splits into a lovely double star - but I recommend waiting until next spring to view it. At that time it will be higher in the sky. 

(Above: The southern evening sky at 10 pm local time.)

With the moon away, Jupiter is the brightest object in the early evening sky. After dusk, look for it gleaming in the southwestern sky. It will set in the west after 2 am local time. On a typical night, even a backyard telescope will show you Jupiter’s two main equatorial stripes and its four Galilean moons, named Io, Europa, Callisto, and Ganymede. The moons always form a rough line flanking the planet. If you see fewer than four, then some are in front of Jupiter, or hidden behind it. 

From time to time, the small, round black shadows cast by the Galilean moons become visible in amateur telescopes as they cross (or transit) Jupiter’s disk. After midnight on Saturday night, Io’s shadow will start to transit the northern part of Jupiter at 12:44 am. Unfortunately, Jupiter will set in the Eastern Time Zone before its passage is complete; but observers farther west can watch the entire event. 

Due to Jupiter’s rapid 10-hour rotation period, the Great Red Spot (or GRS) is only observable from Earth every 2nd or 3rd night, and only during a predictable three-hour window. The GRS will be easiest to see using a medium-sized, or larger, aperture telescope on an evening of good seeing (steady air). If you’d like to see the Great Red Spot in your telescope, it will be crossing the planet tonight (Sunday evening) from dusk to 11 pm EDT, on Tuesday night from 10:52 pm to 12:30 am EDT, on Thursday from 11 pm to 2:30 am EDT, and after dusk on Friday and Sunday. I posted a calendar of Jupiter’s doings here. 

Yellow-tinted Saturn will remain visible from dusk until almost dawn this month. The ringed planet’s position in the sky is just to the upper left (celestial east) of the stars that form the teapot-shaped constellation of Sagittarius (the Archer). Saturn is quite a bit dimmer than Jupiter. To find it, look about 3 fist diameters to the lower left (east) of Jupiter. Dust off your telescope! Once the sky is dark, even a small telescope will show Saturn's rings and several of its brighter moons, especially Titan! Because Saturn’s axis of rotation is tipped about 27° from vertical (a bit more than Earth’s axis), we can see the top surface of its rings, and its moons can appear above, below, or to either side of the planet. During this week, Titan will migrate counter-clockwise around Saturn, moving from the upper right of Saturn tonight (Sunday) to the lower left of the planet next Sunday. (Remember that your telescope will flip the view around.) 

For night owls, tiny blue Neptune is in the southeastern pre-dawn sky, among the stars of Aquarius (the Water-Bearer). The planet will be rising before 10 pm local time this week. You’ll find the magnitude 7.8 Neptune sitting a thumb’s width to the left (east) of a medium-bright star named Phi (φ) Aquarii. The planet is actually moving slowly toward that star! 

Blue-green Uranus will be rising at about midnight local time this week. It is sitting below the stars of Aries (the Ram) and is just a palm’s width above the head of Cetus (the Whale). At magnitude 5.8, Uranus is bright enough to see in binoculars under dark skies. 

Venus is above the east-northeastern sky, barely bright enough to see within the pre-dawn twilight sky that surrounds it. Sinking ever-closer to the rising sun, Venus will be rising at about 5:30 am local time all week. By the end of this week, Mercury will be easier to see than Venus. The swift, innermost planet is climbing away from the sun. Your best opportunity to see it will be at at about 5:30 am local time. 

A Summer Triangle Tour

When you are out on the next clear night, be sure to look for the three bright and beautiful blue-white stars of the Summer Triangle asterism, which shines high in the eastern sky in late July and early August. Once you have it identified, you can find some treasures within it, and follow its progress across the night sky until it finally disappears in late fall. 

(Above: The evening eastern sky features the Summer Triangle formed by the stars Vega, Deneb, and Altair. The Milky Way passes through it.)

Find an open area and face east. The very bright star Vega will be almost straight over your head. It’s the fifth brightest star in the entire night sky and one of the first stars to appear after dusk. Now look for the other two corners of the triangle. Altair, not as bright as Vega, sits about 3.5 outstretched fist diameters (34°) to the lower right of it. The third star, Deneb, is about 2.5 fist diameters (24°) to the lower left of Vega, and is higher up than Altair. It’s a very big triangle! 

Can you see the four fainter stars forming a small, upright parallelogram just below Vega? That shape is about a thumb’s width wide and a few finger widths tall. This box is the body of the musical harp that makes up the constellation of Lyra (the Lyre). Vega marks the top of the instrument’s neck. Vega’s visual magnitude, or brightness, is the zero reference point for the scale we use to define stars’ brightness values. Objects brighter than Vega have values lower than zero, and vice versa. Antares, the reddish star near Jupiter this summer, has a value of about 1, making it 2.5 times dimmer than Vega. (It’s a logarithmic scale.) 

(Above: A detailed view of Lyra, the Harp. The constellation features many double stars, including the Double Double, located a finger’s width from Vega)

Vega also forms a little triangle with two other dim stars, each about a finger’s width apart. The star to Vega’s upper left is Epsilon Lyrae, also known as the Double Double. Can you tell it’s actually two stars crammed tightly together? Try using binoculars. When magnified in a telescope, each star splits again! 

Deneb marks the tail of great Cygnus (the Swan). Look for a modest star sitting about two fist diameters (22°) to the right of Deneb. That’s Albireo, a colourful double star that marks the swan’s head. (I like to think of Albireo as the centre of doc Brown’s flux capacitor. The Summer Triangle stars are the gadget’s corners!) Albireo was given a single star name before telescopes revealed that there were two stars there! 

A widely spaced string of medium-bright stars aligned up-down traces out the swan’s wings. (Look closer to Deneb than Albireo for them – swans have long necks!) The brighter star in the middle of the wing span is Sadr, marking the swan’s belly. If you are in a dark location, you should also be able to see that the Milky Way runs right through Cygnus, as if she is about to land for a swim on that celestial river! 

The most southerly of the triangle’s corners is marked by Altair – the head of the great eagle Aquila. In fact, its name translates from “the flying eagle”. At only 16.8 light-years distance, Altair is one of the nearest bright stars – so close that its surface has been imaged! The star also seems to be spinning 100 times faster than our sun, probably generating an equatorial bulge. Like Cygnus, the Aquila the eagle is oriented with its wingtips up-down. The tail bends to the lower right. Two little stars named Terazed (above) and Alshain (below) sit on either side of Altair, like a balance. As a matter of fact, those two little stars’ names derive from an old-fashioned scale balance. 

Grab your binoculars and look about midway between Vega and Altair for a little grouping of stars called The Coathangar. (Hint: For North American observers, it’s oriented with the hook downwards to the right.) Finally, have a look for two little constellations in the area. Sagitta (the Arrow) comprises five faint stars running left-right, above Altair. The three on the right (west) end form the feathers. Below Sagitta, and about 1.3 fist diameters (13°) to the left of Altair is cute little Delphinus (the Dolphin). Four stars form a diamond-shaped body and another star to the lower of that right marks the tail flukes! The star names for Delphinus include a very interesting story. Look it up! 

There’s one more small constellation inside the Summer Triangle, but its dim stars make it difficult to make out. It’s called Vulpecula (the Fox), and it sits about a palm’s width above and parallel to Sagitta. I’ll post a star chart for the entire area here. Two birds, a dolphin, and a fox! (And – there’s the lizard Lacerta just to the east and a little foal Equuleus below Delphinus!) Enjoy your tour of the triangle and visit to this celestial zoo! 

(Above: The Summer Triangle neighbourhood includes a dolphin, a fox, a foal, and a lizard.)

Touring the Dark July Southern Sky

If you missed last week’s tour through the scorpion, the teapot, and the shield, I posted it with sky charts here. 

Public Astro-Themed Events

Taking advantage of dark, moonless evening skies this week, astronomers with the RASC Toronto Centre will gather for dark sky stargazing at Long Sault Conservation Area, northeast of Oshawa on (only) the first clear evening (Monday to Thursday) this week. You don’t need to be a RASC member, or own any equipment, to join them. Check here for details and watch the banner on their homepage or their Facebook page for the GO or NO-GO decision around 5 pm each day. 

Every Monday evening, York University’s Allan I. Carswell Observatory runs an online star party - broadcasting views from four telescopes/cameras, answering viewer questions, and taking requests! Details are here. On Wednesday nights they offer free public viewing through their rooftop telescopes. If it’s cloudy, the astronomers give tours and presentations. Details are here. 

At 8:30 pm on Wednesday, July 31, the High Park Nature Centre will host a free public Urban Bat Walk followed by stargazing (weather permitting). Check here for details. 

On Thursday, August 1, starting at 11 am, U of T’s AstroTour planetarium show will be a Kids Summer Break Show. Find tickets and details here. 

On Thursday, August 1, starting at 9 pm, U of T’s AstroTour will present a talk entitled A Brief History of Everything, followed by stargazing and a planetarium show. Find tickets and details here. 

Eastern GTA sky watchers are invited to join the RASC Toronto Centre and Durham Skies for solar observing and stargazing at the edge of Lake Ontario in Millennium Square in Pickering on Friday evening, August 2, from 6 pm to 11 pm. Details are here. Before heading out, check the RASCTC home page for a Go/No-Go call in case it's too cloudy to observe. The rain date is Saturday. 

On Friday, August 2, starting at 7 pm, U of T’s AstroTour planetarium show will be Grand Tour of the Cosmos. Find tickets and details here. 

The next RASC Family Night at the David Dunlap Observatory will be on Saturday, August 10. There will be sky tours in the Skylab planetarium room, space crafts, a tour of the giant 74” telescope, and viewing through lawn telescopes (weather permitting). The doors will open at 8:30 pm for a 9 pm start. Attendance is by tickets only, available here. If you are a RASC Toronto Centre member and wish to help us at DDO in the future, please fill out the volunteer form here. And to join RASC Toronto Centre, visit this page.

Keep looking up, and enjoy the sky when you do. I love questions and requests - so, send me some!

[astrogeoguy]

Maximum Mercury, Dark Nights, Bright Jupiter, and the Best of Boötes!

(Above: The Pinwheel Galaxy, aka Messier 101, is located between Boötes and Ursa Major. This image was taken using data from the Hubble Space Telescope and the Subaru Telescope and then processed by Robert Gendler. NASA APOD for June 14, 2015.)

Hello, Stargazers!

Here are your Astronomy Skylights for the week of June 23rd, 2019 by Chris Vaughan. Feel free to pass this along to your friends and send me your comments, questions, and suggested topics. I repost these emails with photos at http://astrogeoguy.tumblr.com/ where all the old editions are archived. You can also follow me on Twitter as @astrogeoguy! Unless otherwise noted, all times are Eastern Time. Please click this MailChimp link to subscribe to these emails. If you are a teacher or group leader interested joining me on a guided field trip to York University’s Allan I. Carswell Observatory or the David Dunlap Observatory, visit www.astrogeo.ca.

I can bring my Digital Starlab inflatable planetarium to your school or other daytime or evening event. Contact me, and we’ll tour the Universe together!

The Moon and Planets

The moon will be out of the evening sky this week as it slides towards its meeting with the pre-dawn sun next week. Meanwhile, it’s a perfect week to explore the night sky – now that the Northern Hemisphere daylight period is slowly shortening and our nights lengthening! Here are the Skylights! 

Monday morning will find the late-rising moon among the modest stars of Aquarius (the Water-Bearer) in the southeastern pre-dawn sky; and then our natural satellite will linger in view in the southwestern sky until mid-day. For the rest of the week, the waning moon will pass through Cetus (the Whale) and dip into Pisces (the Fishes). On Tuesday morning at 5:46 am Eastern Time, the moon will officially reach its last quarter phase – appearing half-illuminated on the left-hand (its western) side. 

On Saturday morning, the old, slim, crescent moon will land in the western end of Taurus (the Bull). On Sunday morning, just before sunrise, see if you can spot the delicate moon sitting a few finger widths above Taurus’ brightest star, Aldebaran.

(Above: The distant, dim, blue planet Neptune is among the stars of Aquarius, shown here for 4 am local time on June 29, 2019. The magnitude 7.9 planet will be sitting a thumb’s width to the left (east) of a medium-bright star named Phi (φ) Aquarii.)

While we’re talking pre-dawn, remember that Distant and dim, blue Neptune is in the southeastern pre-dawn sky, among the stars of Aquarius (the Water-Bearer). The planet will be rising shortly after midnight local time this week. You’ll find the magnitude 7.9 planet sitting a thumb’s widths to the left (east) of a medium-bright star named Phi (φ) Aquarii. 

Blue-green Uranus will be rising just after 3 am local time this week. It is sitting among the stars of Aries (the Ram) and is just a palm’s width above the head of Cetus. The large main-belt asteroid Vesta is nearby - a palm’s width below Uranus. Look for Vesta sitting only half a finger’s width below the modest star Xi (ξ) Ceti (and also named Al Kaff al Jidhmah). They will appear together in the field of view of a backyard telescope.

(Above: The blue-green planet Uranus is among the stars of southwestern Aries, shown here for 4 am local time on June 29, 2019. The asteroid Vesta is located a palm’s width below Uranus this week. Vesta is only half a finger’s width below the modest star Xi (ξ) Ceti, labelled here as Al Kaff al Jidhmah.)  

Venus is bright enough to see within the pre-dawn twilight sky that surrounds it, but it is sitting very low in the northeast - sinking ever-closer to the rising sun. Venus will be rising at about 4:40 am local time all week.

The blazingly-bright object that you’ve been seeing in the southeastern evening sky recently is mighty Jupiter. We are still near our closest approach to the planet for 2019, increasing its apparent brightness and the size of its banded disk and moons in binoculars and telescopes. This week Jupiter will be rising at about 7:30 pm local time, before sunset. 

(Above: Io’s shadow will be completing a transit on Jupiter (with the Great Red Spot) just before 11 pm EDT on Thursday evening, so you can start to look for them as soon as the sky darkens. This image shows the situation at 10:15 pm EDT.)

From time to time, the small, round black shadows cast by Jupiter’s four Galilean moons become visible in amateur telescopes as they cross (or transit) Jupiter’s disk. Starting at about 2 am EDT on Wednesday morning, Io and its shadow will cross Jupiter for more than two hours. Io’s shadow will also be completing a transit (with the Great Red Spot) just before 11 pm EDT on Thursday evening, so you can start to look for that as soon as the sky darkens. On Saturday morning, Europa and its shadow will cross Jupiter for two hours (with the Great Red Spot), starting at about 2:40 am EDT. Jupiter will set while they are crossing. 

Due to Jupiter’s rapid 10-hour rotation period, the Great Red Spot (or GRS) is only observable from Earth every 2nd or 3rd night, and only during a predictable three-hour window. The GRS will be easiest to see using a medium-sized, or larger, aperture telescope on an evening of good seeing (steady air). If you’d like to see the Great Red Spot in your telescope, it will be crossing the planet on Monday evening from 10 pm until 12:30 am EDT. More GRS viewing opportunities will occur on Wednesday from 11 pm to 2 am EDT, Thursday evening before 11:30 pm EDT, and on Saturday night in the hours before midnight. 

(Above: The bright planets Jupiter and Saturn dominate the southern evening sky this month, as shown here at 11 pm local time. Saturn is 30 degrees to the east (lower left) of Jupiter.)

Yellowish Saturn will be rising in the east-southeast just before 10 pm local time this week. Its position in the sky is just to the left (east) of the stars that form the teapot-shaped constellation of Sagittarius (the Archer). Saturn is quite a bit dimmer than Jupiter. To find it, look about 3 fist diameters to the lower left (east) of Jupiter. Dust off your telescope! Once the sky is dark, even a small telescope will show Saturn's rings and several of its brighter moons, especially Titan!  Because Saturn’s axis of rotation is tipped about 27° from vertical (a bit more than Earth’s is), we can see the top surface of its rings, and its moons can appear above, below, or to either side of the planet. During this week, Titan will migrate counter-clockwise around Saturn, moving from the upper right tonight, to the left of the planet next Sunday. (Remember that your telescope will flip the view around.) 

Dim, reddish Mars and brighter Mercury are still hanging out together just above the northwestern horizon after sunset this week, but not as close together as last week. Mercury will become easier to spot every night while it climbs away from the sun and brightens. The best time to look for Mercury falls between 9:45 and 10:15 pm local time. Tonight (Sunday) Mercury will peak in visibility when it reaches its widest separation, 25 degrees east of the Sun, for the current apparition. Look for Mars sitting a few finger widths to the upper left of Mercury. (Take care that the sun has set before attempting to view them using binoculars or a telescope.) You can also look for the bright stars Castor and Pollux of Gemini (the Twins) sitting to the upper right of the two planets.

(Above: Mercury is climbing away from the sun and drawing away from dimmer Mars, as shown her at 10 pm local time on Sunday evening. Mercury swings widest from the sun on the same date, and then will start dropping sunward again.)

The Treats of Boötes

The absent moon for the next two weeks and the lovely early summer nights offer a fine opportunity to explore the realm of Boötes (“Bow-Oh-tees”), the Herdsman or Plowman. Grab your binoculars and your favorite star-gazing partner and head outside. Let’s tour!

After it gets dark, face southwest and look about halfway up the sky for a very bright, orange-tinted star named Arcturus. The fourth brightest star in the entire night sky, Arcturus means “Guardian of the Bear” in Greek, because it rises after Ursa Major (the Big Bear), which sits to its upper right (west). Arcturus is that colour because it is just passing middle-age for a star, starting on its way towards the red supergiant stage. In Chinese, Arcturus is known as Dà Jiǎo 大角, "Great Horn". 

(Above: Shown here at 11 pm local time, the western evening sky in late June / early July annually features the constellation of Boötes, the Herdsman. It is easy to trace out by starting at the very bright, tinted star Arcturus.)

Arcturus marks the bottom tip of the large, kite-shaped constellation Boötes, traditionally represented as a Herdsman or Plowman. The rest of the stars in the kite are medium-bright and visible under party light-polluted skies. About a fist’s diameter above and slightly left (east) of Arcturus are two close-together stars. The higher one named Izar, meaning “Loin Cloth”, is moderately bright. The lower one is much fainter. In a telescope, Izar splits into a gorgeous double star – one is golden and the other is white or greenish. 

Moving another fist’s width upwards along the same line brings us to the Herdsman’s eastern shoulder, a modest star designated Delta Boötis, or Thiba. (The word Boötis is latin for “belonging to Boötes.) Thiba is a sun-like star, about ten times the mass of our sun, sitting 117 light-years away. Looking up and to the right about 7.5°, we find a star named Nekkar “Ox Driver”, marking the constellation’s head (or tip of the kite). This is an elderly blue star passing through a phase that is causing it temporarily resemble a large version of our sun - on its way to becoming a brighter red giant. 

Sitting about three finger widths towards the upper left from the line connecting Delta Boötis and Nekkar (shoulder and head) is a triple star named Alkalurops, a name derived from “Shepherd’s Staff”. Two of Alkalurops’ stars can be discerned with good eyes or binoculars, and one of these becomes two stars when viewed in a telescope. All three stars are orbiting in a dance that takes at least 125,000 years for a turn. 

As we head from Nekkar back down the crooked western side of the kite, we first stop at a medium bright star named Seginus, which marks the western shoulder. Seginus is also evolving - presently a white giant star that is on the way towards becoming a red giant one day. This 85 light-years distant star is spinning about 70 times faster than our sun! 

Moving less than halfway down the constellation towards Arcturus, we find a modest star sitting about four finger widths to the right of Izar. This star, designated Rho (ρ) Boötis, marks the gentleman’s western hip. There’s a noticeable small star just to its left named Sigma Boötis. 

Descending from Arcturus to the east and west are some minor stars that mark the legs and feet. The eastern foot, less than a fist’s diameter to the lower left of Arcturus, is designated Zeta Boötis. In a telescope it is revealed to be a nice matched pair of close together white stars. Moving about four finger widths down the western leg brings us to the bright star Muphrid. It’s also classed like our sun, and is actually the same distance from us as Arcturus. But its inherent brightness is less, so it looks much dimmer. Dropping down slightly and moving farther right is the star Upsilon Boötis, a very distant red giant star.

(Above: A sky chart identifying all the major stars of Boötes. Sweep the sky to the right of Arcturus with binoculars to find the small, fuzzy blob of the globular star cluster labelled as M3)  

All the stars in our galaxy are in motion, jostling as they orbit the galactic centre every quarter of a billion years or so. Some stars’ move faster, or are closer to us – so they exhibit a greater apparent motion across the sky. Astronomers call this Proper Motion. That’s why star charts need to be updated regularly. Arcturus has a very high proper motion southward. In a few thousand years, the herdsman’s legs will be bent upwards with Arcturus below his knees! 

Boötes extends way up to the tip of the Big Dipper’s handle. Just before you get there, look for a tight grouping of three stars that represent the herdsman’s upraised hand. The star names are Asellus Primus, Asellus Secundus, and Asellus Tertius “First, second, and Third Donkey”. Two of them are telescopic double stars, but the area around them is a lovely rich field for viewing. The famous Pinwheel Galaxy (Messier 101) is located only a few finger widths above them! I’ll post a sky chart here.

Oh, Look – it’s Ophiuchus!

If you missed last week’s information about the large summer constellation of Ophiuchus (the Serpent Bearer) and its loads of deep sky treats, I posted it here. 

Public Astro-Themed Events

Every Monday evening, York University’s Allan I. Carswell Observatory runs an online star party - broadcasting views from four telescopes/cameras, answering viewer questions, and taking requests! Details are here. On Wednesday nights they offer free public viewing through their rooftop telescopes. If it’s cloudy, the astronomers give tours and presentations. Details are here. 

On Friday, June 28, starting at 7 pm, U of T’s AstroTour will present their planetarium show The Life and Death of Stars. Find tickets and details here. 

The next RASC Family Night at the David Dunlap Observatory will be on Saturday, July 13. There will be sky tours in the Skylab planetarium room, space crafts, a tour of the giant 74” telescope, and viewing through lawn telescopes (weather permitting). The doors will open at 8:30 pm for a 9 pm start. Attendance is by tickets only, available here. If you are a RASC Toronto Centre member and wish to help us at DDO in the future, please fill out the volunteer form here. And to join RASC Toronto Centre, visit this page.

Keep looking up, and enjoy the sky when you do. I love questions and requests - so, send me some!

[astrogeoguy]

Jupiter at Peak Planet, a Late-night Lunar X, and Mars and Mercury Hang Out in the West!

(Above: At this first quarter, a feature called the Lunar X will be visible in strong binoculars and small telescopes. For a few hours, the illuminated rims of the craters Parbach, la Caille, and Blanchinus will form a small, but very obvious X-shape located at moon coordinates 2° East and 24° South. This image was taken by Jerry Lodigruss, NASA APOD for March 11, 2009)

Hello, Stargazers!

Here are your Astronomy Skylights for the week of June 9th, 2019 by Chris Vaughan. Feel free to pass this along to your friends and send me your comments, questions, and suggested topics. I repost these emails with photos at http://astrogeoguy.tumblr.com/ where all the old editions are archived. You can also follow me on Twitter as @astrogeoguy! Unless otherwise noted, all times are Eastern Time. Please click this MailChimp link to subscribe to these emails. If you are a teacher or group leader interested joining me on a guided field trip to York University’s Allan I. Carswell Observatory or the David Dunlap Observatory, visit www.astrogeo.ca.

I can bring my Digital Starlab inflatable planetarium to your school or other daytime or evening event. Contact me, and we’ll tour the Universe together! 

Public Astro-Events

Taking advantage of the moon and other bright objects in the sky this week, the RASC Toronto Centre astronomers will hold their free monthly public City Sky Star Party in Bayview Village Park (steps from the Bayview subway station), starting around 8 pm on the first clear weeknight this week (Mon through Thu only). You don’t need to be an RASC member, or own any equipment, to join them – looks are free! Check here for details, and check the banner on their website home page or Facebook page for the GO or NO-GO decision around 5 pm each day. 

Every Monday evening, York University’s Allan I. Carswell Observatory runs an online star party - broadcasting views from four telescopes/cameras, answering viewer questions, and taking requests! Details are here. On Wednesday nights they offer free public viewing through their rooftop telescopes. If it’s cloudy, the astronomers give tours and presentations. Details are here. 

To celebrate the best views of Jupiter for 2019, York University’s Allan I. Carswell Observatory will hold a free public Jupiter-viewing session on top of the Arboretum Parking Structure on Monday or Tuesday (whichever night is clear first). Viewing runs from 10 pm to midnight, and details are here. Follow @yorkobservatory on social media for the GO/no-GO notices. Usual parking fees will apply. 

Weather permitting, on Tuesday, June 11 from 9 to 10:30 pm, astronomers from RASC – Mississauga will hold a free public star party at the Riverwood Conservancy, 4300 Riverwood Park Lane, Mississauga. Details are here. 

On Wednesday evening from 7 to 9 pm at the Michael DeGroote Centre for Learning at McMaster University, Dr. Sarah M Hörst from Johns Hopkins University will present a free lecture entitled Titan: Ingredients for Life. Details and registration are here. 

On Thursday, June 13, starting at 7 pm, U of T’s AstroTour will present their planetarium show Grand Tour of the Cosmos. Tickets and details are here. 

On Friday evening from 7:30 to 10 pm at the Hamilton Spectator building, the Hamilton astronomers will present a free public talk by Brian McNamera entitled 1919-2019: A Century of Black Holes. Details are here. 

On Friday, June 14 from 8 to 11 pm, adults can enjoy some suds with their science at Astronomy on Tap T.O. at the Great Hall on Queen Street West, a free event hosted by the U of T’s Dunlap Institute. Talks, trivia, contest giveaways, and more! Details are here. 

The Annual General Assembly of the Royal Astronomical Society of Canada will be held at York University this weekend. Saturday and Sunday will be devoted to free, fun, hands-on activities for space-enthusiasts of all ages. View the sun safely (weather permitting), spend some time in an inflatable planetarium, make your own comet or create some messy moon craters, and make some space art and crafts. Details are here. 

The next RASC Lecture Night at the David Dunlap Observatory will be on Saturday, June 15. There will be sky tours in the Skylab planetarium room, space crafts, a tour of the giant 74” telescope, and viewing through lawn telescopes (weather permitting). The doors will open at 8:30 pm for a 9 pm start. Attendance is by tickets only, available here. If you are a RASC Toronto Centre member and wish to help us at DDO in the future, please fill out the volunteer form here. And to join RASC Toronto Centre, visit this page. 

The Moon and Planets

Both the moon and Jupiter will be dominating our night skies this week, worldwide. Here are the Skylights! 

The moon will tempt you to view it throughout this week. Sunday evening will feature the nearly half-illuminated moon tucked a palm’s width below the stars that form the eastern, back half of Leo (the Lion). Hours later, at 2 am Eastern Time on Monday morning, the moon will officially reach its First Quarter phase. At that time, it will be positioned 90 degrees away from the sun. 

The term expresses that the moon has completed the first quarter of its orbit around Earth since the previous New Moon. The relative positions of the Earth, sun, and moon cause us to see the moon half-illuminated - on its eastern side. At first quarter, the moon always rises around noon and sets near midnight, so it is also visible in the afternoon daytime sky, too. The evenings around first quarter are the best times to see the lunar terrain while it is dramatically lit by low-angled sunlight.

 At this first quarter, a feature called the Lunar X will be visible in strong binoculars and small telescopes. For a few hours, the illuminated rims of the craters Parbach, la Caille, and Blanchinus will form a small, but very obvious X-shape located at moon coordinates 2° East and 24° South. That point is on the terminator (the pole-to-pole line that divides the lit and dark hemispheres) and about one third of the way up from the southern pole of the moon. The “X” should start to develop around midnight on Sunday. 

From Monday through Thursday, the moon will pass head-to-foot through the large constellation of Virgo (the Maiden). Every night, our natural satellite will fill up with light and set later as it swings wider from the sun. On Thursday and Friday, the nearly full moon will cross Libra (the Scales). 

On the weekend, the moon will hop past Jupiter, landing on Jupiter’s upper right on Saturday and then dropping to Jupiter’s lower left on Sunday. On both nights, notice the relative positions of the two objects while they are over the eastern horizon, and compare that to the way they look hours later. Earth’s rotation causes constellations and planets to flip by 180 degrees as they cross the sky from east to west. The June full moon will occur in the wee hours of next Monday, so the moon will look full on Sunday evening, too. 

This is a big week for Jupiter – literally! On Monday, June 10, Earth’s faster orbit will pass Jupiter on the inside track, causing Jupiter to be positioned exactly opposite the sun in our sky, worldwide. Planets at opposition always rise at sunset, and remain visible all night long. On Monday, Jupiter will also be closer to Earth than on any other date this year – only 640.9 million km, or 4.284 Astronomical Units from us. (1 A.U. is the average sun-Earth separation.) The planet’s light will be taking 36 light-minutes to reach us – meaning that we are seeing Jupiter more than half an hour in the past! 

Jupiter will also shine at its brightest (visual magnitude -2.6) for 2019, and its apparent disk diameter will max-out at 46 arc-seconds. (That’s 2.5% of the full moon’s diameter.) Don’t worry if your skies are cloudy on June 10. Jupiter will be about as good for a week surrounding that date, and then it will slowly start to shrink in size and brightness. We’ll be enjoying Jupiter through our telescopes all summer long! 

(Above: Starting late on Tuesday evening, observers in the Americas can see the black shadows of two of Jupiter’s moons on Jupiter at the same time! At 11:29 pm EDT, Ganymede’s shadow will join Io’s shadow already in transit. The two shadows will cross Jupiter for 64 minutes until Io’s shadow moves off the planet at 12:33 am. This image shows Jupiter at midnight EDT.)

Around opposition, Jupiter’ moons are more visible, too. From time to time, the small, round black shadows cast by Jupiter’s four Galilean moons become visible in amateur telescopes as they cross (or transit) Jupiter’s disk. Starting late on Tuesday evening, observers in the Americas can see two of those shadows on Jupiter at the same time! At 11:29 pm EDT, Ganymede’s shadow will join Io’s shadow already in transit. The two shadows will cross Jupiter for 64 minutes until Io’s shadow moves off the planet at 12:33 am. Ganymede’s shadow will continue to transit the northern polar region of Jupiter until 1:50 am EDT. 

Due to Jupiter’s rapid 10-hour rotation period, the Great Red Spot (or GRS) is only observable from Earth every 2nd or 3rd night, and only during a predictable three-hour window. The GRS will be easiest to see using a medium-sized, or larger, aperture telescope on an evening of good seeing (steady air). If you’d like to see the Great Red Spot in your telescope, it will be crossing the planet after midnight tonight (Sunday). More GRS viewing opportunities occur in the hours surrounding 9:45 pm EDT on Monday evening, 11:15 pm EDT on Wednesday, and 1 am EDT on Saturday.

(Above: Jupiter will reach peak visibility for 2019 on June 10, when it reaches opposition. Jupiter and dimmer Saturn (at lower left) will spend the next several months in the southern evening sky, on opposite sides of the Milky Way, as shown here for midnight this week.)  

Yellowish Saturn will be rising in the east-southeast a little before 11 pm local time this week. Its position in the sky is just to the left (east) of the stars that form the teapot-shaped constellation of Sagittarius (the Archer). Saturn is quite a bit dimmer than Jupiter. To find it, look about 2.5 fist diameters to the lower left (east) of Jupiter. Dust off your telescope - because even a small one will show its rings and several of its brighter moons!

(Above: The ice giant planets Uranus and Neptune are both in the eastern pre-dawn sky among the stars of Aries and Aquarius, respectively, as shown here at 4:30 am local time.)  

Distant and dim, blue Neptune is in the southeastern pre-dawn sky, among the stars of Aquarius (the Water-Bearer). The planet will rise before 2 am local time. After mid-June, Neptune will become part of the evening sky. Brighter, blue-green Uranus is rising at about 3 am local time, and is sitting among the stars of Aries (the Ram). 

Last to rise is our bright, next-door neighbour Venus. She is sitting low in the east-northeastern pre-dawn sky this week, creeping ever-closer to the rising sun. Venus will shine with a steady, unmoving light - unlike airplanes.

(Above: Mercury and Mars are situated low in the western sky after sunset this week, as shown here for 10 pm local time on Friday. Mercury will be drawing closer to Mars all week.)  

Mars and Mercury are hanging out just above the northwestern horizon after sunset this week. Mercury will become easier to spot every night because it is climbing away from the sun and brightening. The best time to look for it falls between 9:45 and 10:15 pm local time. Mercury is heading directly towards dimmer Mars. Tonight, Mars will be about a palm’s width to the upper left of Mercury. By Sunday, that will reduce to a finger’s width! And next week, those two planets will “kiss”!  

The Big Dipper as a Sky Tool

If you missed last week’s information about measuring the sky using the Big Dipper asterism, I posted it here. 

Satellites

There are no visible Iridium Flares predicted for the GTA this week. The ISS (International Space Station) will not be visible over the GTA this week. 

Keep looking up, and enjoy the sky when you do. I love questions and requests - so, send me some!

[astrogeoguy]

Bright Stars, a Comet You can Catch, and the Waxing Moon Tours the Night’s Sights!

(Above: A double shadow transit caused by Io and Europa will occur on Jupiter on Thursday, August 23, as shown here at 10:40 pm EDT. Only observers west of the Eastern time zone will be able to see both shadows.)

Astronomy Skylights for this week (from August 19th, 2018) by Chris Vaughan. (Feel free to pass this along to friends and send me your comments, questions, and suggested topics.) I post these with photos at http://astrogeoguy.tumblr.com/ where the old editions are archived. You can also follow me on Twitter as @astrogeoguy! Unless otherwise noted, all times are Eastern Time. Please click this MailChimp link to subscribe to these emails. If you are a teacher or group leader interested joining me on a guided field trip to York University’s Allan I. Carswell Observatory, or another in your area, visit www.astrogeo.ca.

If you’d like me to bring my Digital Starlab inflatable planetarium to your school or other daytime or evening event, visit DiscoveryPlanetarium.com and request me. We’ll tour the Universe together!

Public Events

Every Monday evening, York University’s Allan I. Carswell Observatory runs an online star party - broadcasting views from four telescopes/cameras, answering viewer questions, and taking requests! Details are here. On Wednesday evenings after dark, they offer free public viewing through their telescopes. If it’s cloudy, the astronomers give tours and presentations. Details are here. 

On Tuesday, August 21, starting at 8:30 pm, the RASC Mississauga will host a free public star party at the Riverwood Conservancy. Details are here. 

On Thursday, August 23 at 6 pm, adults can enjoy some alcohol with their science at Solar System Social at Burdock on Queen St. West. A panel of experts will discuss Who Deserves To Explore Space. Tickets and details are here. 

On Friday, August 24, starting at 7 pm, the U of T AstroTour will present their planetarium show entitled Grand Tour of the Cosmos. Tickets and details are here. 

If it’s sunny on Saturday morning, August 25 from 10 am to noon, astronomers from the RASC Toronto Centre will be setting up outside the main doors of the Ontario Science Centre for Solar Observing. Come and see the Sun in detail through special equipment designed to view it safely. This is a free event (details here), but parking and admission fees inside the Science Centre will still apply. Check the RASC Toronto Centre website or their Facebook page for the Go or No-Go notification. 

The next RASC Public Event at the David Dunlap Observatory will be Speaker Night on Saturday, August 25. There will a lecture by an astronomer, space crafts, a tour of the giant 74” telescope, and viewing through lawn telescopes (weather permitting). The doors will open at 7:30 pm for an 8 pm start. Attendance is by tickets only, available here. If you are a RASC member and wish to help us at DDO in the future, please fill out the volunteer questionnaire here. And to join RASC, visit this page. 

A Binocular Comet

Comet 21P/Giacobini-Zinner has been gradually brightening for some time because it is approaching Earth’s orbit. This week, you should be able to see the faint fuzzy greenish object in binoculars or a small telescope, if you can escape city lights - and especially after midnight when the bright moon has set. The comet is in the north-northeastern sky and heading downwards every night on a track that lies about a fist’s diameter (10°) to the left of the bright star Mirfak in Perseus (the Hero). 

(Above: The path of Comet 21P/Giacobini-Zinner in the northeastern sky this week, shown here at 11 pm local time.)

The Moon and Planets

This week ends with next Sunday’s August full moon, known as the “Sturgeon Moon”, “Red Moon”, “Green Corn Moon”, and “Grain Moon”. This one always shines in or near the stars of Aquarius (the Water-Bearer) or Capricornus (the Sea-Goat), but you’ll be hard-pressed to see the dim stars in those modest constellations due to so much bright moonlight. 

Full moons occur when the moon is at opposition, with Earth positioned between our natural satellite and the sun. Because of this, full moons always rise around sunset and set around sunrise. They are illuminated by vertically arriving sunlight, so nothing on the moon can cast a shadow when viewed from Earth. Moon phases can occur at any time of the day or night. This one occurs at 7:56 am Eastern Daylight time on Sunday morning, so the moon will appear a hair less than full on Saturday evening, and a hair less than full on Sunday evening, too. Binoculars or a telescope will reveal a narrow strip of shadowed terrain along the moon’s left (its western) edge on Saturday. That strip will shift over to the moon’s right (its eastern) edge on Sunday evening. To see the moon completely free of shadows, i.e., precisely full, you will need to look at it at the time I mentioned above. 

Meanwhile, the moon will make a pretty sight in our evening sky all week long as it waxes fuller and slides eastward along its orbit. Tonight, it will be perched above the distinctive constellation of Scorpius (the Scorpion), about a fist’s diameter above that deadly creature’s heart, the bright reddish star Antares “Rival of Mars”. 

In the southern sky after dusk on Monday, the waxing gibbous moon will sit 4 finger widths to the upper right of bright, yellowish Saturn. The two objects will easily fit within the field of binoculars. Over the course of the evening, the moon’s separation from the ringed planet will have noticeably decreased due to the moon’s eastward motion. 

(Above: On Tuesday evening, August 21, as shown here at 11 pm local time, the moon will sit above the easy-to-see Teapot-shaped asterism of Sagittarius. Once the moon leaves the sky next week, look for the Milky Way’s “steam” rising from the spout.)

On Tuesday evening, the moon will shift to sit above the Teapot-shaped asterism of stars that form Sagittarius (the Archer). This informal star pattern features a flat bottom formed by the stars Ascella “Armpit” on the east and Kaus Australis “Southern Bow” on the west, a triangular pointed spout pointing west, marked by the star Alnasl “Arrowhead”, and a pointed lid marked by the star Kaus Borealis “Northern Bow”. The stars Nunki and Tau Sagittarii form its handle. The asterism reaches maximum height above the southern horizon around 10 pm local time, when it will look as if it’s serving its hot beverage –the Milky Way appearing to be the steam rising as the teapot pours its celestial brew. (To see the Milky Way’s “steam”, look next week when the moon has moved away.) I’ll post a sky chart here. 

On Wednesday and Thursday evening respectively, the moon will hop from bright reddish Mars’ upper right to its upper left.

(Above: The early evening sky, shown here Sunday evening at 9 pm local time, features all the naked-eye planets - Venus, Jupiter, Saturn, and Mars.) 

Extremely bright Venus is descending the western early evening sky a little by little each day as its orbit begins to carry it back towards the sun. Tonight it will set at about 9:45 pm local time and a week from now that will move up to 8:30 pm. Meanwhile, the bright planet will appear to be approaching the bright star Spica in Virgo (the Maiden). The effect is caused by Earth’s motion carrying the entire sky westward faster than Venus is moving. They’ll “kiss” next week! In a small telescope, Venus’ disk will resemble a first quarter moon, half-lit on the sunward side (although your telescope might flip the view). The planet will also be growing larger in apparent diameter because it is travelling towards the Earth right now. 

We only have a few more good weeks to enjoy Jupiter this year. This week, the very bright planet will appear in the southwestern sky soon after dusk, and then set in the west-southwest at about 11:15 pm local time. Tonight, Jupiter, which has been slowly shifting eastwards, will pass close above nearby bright star Zubenelgenubi, the brightest star in Libra (the Scales). From here out it will draw farther away every night. In binoculars, you’ll plainly see that Zubenelgenubi is a pair of stars. While you have the binoculars handy, see if you can see Jupiter’s four Galilean moons (Io, Europa, Callisto, and Ganymede) flanking the planet. 

From time to time, the small round black shadows cast by Jupiter’s four Galilean moons become visible in backyard telescopes as they cross (or transit) the planet’s disk. On Thursday, August 23, Io’s shadow will begin to transit at 10:02 pm EDT. Europa’s shadow will join Io’s at 10:58, just as Jupiter is setting in the Eastern time zone, but observers in the west can watch the event. A reasonable backyard telescope will show the black shadows, but a very good telescope is needed to see the moons themselves. More shadow transits are available in other time zones around the world, including some double shadow ones. 

The Great Red Spot (or GRS, for short) takes about three hours to cross Jupiter’s disk. But the planet’s 10-hour rotation period (i.e., its day) means that the spot is only observable from Earth every 2-3 nights. If you’d like to see the GRS, use a medium-sized telescope (or larger). You’ll have your best luck on evenings with steady air – when the stars are not twinkling too much. Try to look within an hour before or after the following times: Sunday, August 19 at 9:46 pm and Friday, August 24 at 8:56 pm. All times are given in Eastern Daylight Time (EDT), so adjust for your local time zone. 

Around 8:40 pm local time, when the first bright stars appear overhead, medium-bright Saturn will appear not too high up the darkening southern sky. The yellow-tinted planet will reach its highest elevation of about 2 fist diameters above the southern horizon at around 9:30 pm, and then descend to set in the west at about 2 am local time. This summer, the ringed planet has been 4 finger widths to the upper right of the “lid” star of the Teapot in Sagittarius (the Archer). As the sky darkens, even a small telescope should be able to show you some of Saturn’s larger moons, especially Titan. Using a clock’s dial analogy, Titan will move counter-clockwise this week from a position at 7 o’clock (to the lower left of it) to 2 o’clock (left from the planet). (Remember that your telescope might flip and/or invert the view. Use the moon to find out how your telescope changes things.) 

Mars will still be very bright this week. Visually, it will appear pink or orangey due to the global dust storm it has experienced recently. Mars will rise over the southeastern horizon at around 7:30 pm local time (give or take, depending on your latitude) and then climb higher until 11:30 pm local time, when it will reach an elevation of about 20° (or two outstretched fist diameters) above the southern horizon. (That will be the best hour to view the planet in a telescope because it will then be shining through the least amount of Earth’s distorting atmosphere.) Note that 20° is lower than many trees and buildings, so a clear southern vista is essential.

(Above: The ice giant planets Uranus and Neptune rise late and remain in view all night to the east of Mars, as shown here at midnight this week.) 

At visual magnitude 5.8, blue-green coloured Uranus is visible from late evening until dawn. You can see it without optical aid under very dark skies, or in binoculars and telescopes under moderately light-polluted skies. The ice giant planet is located in the eastern sky, about 4.5 finger widths to the left of the modestly bright star Torcular (Omega Piscium), which is above the “V” where the two starry cords of Pisces (the Fishes) meet. 

Using a decent quality telescope you can also see the distant and very blue planet Neptune among the dim stars of Aquarius (the Water-bearer). It will rise in the east shortly before 9 pm local time. Look for the magnitude 7.8 planet sitting 1.75 finger widths to the right of the modestly bright star Phi (φ) Aquarii and 4 finger widths to the left of the brighter star Hydor (Lambda Aquarii). 

Mercury will be observable in the eastern pre-dawn sky this week. Look for it low above the east-northeastern horizon at around 5:45 am local time. Next Sunday, Mercury will reach an angle of 18 degrees west of the Sun, its widest separation for this appearance. That means it will rise well before the sun, in a somewhat darker sky. You’ll be able to see it between about 5:15 and 6 am local time.

(Above: On Sunday, August 26, Mercury will reach its largest angle from the sun, and maximum visibility for this morning appearance, as shown here at 5:45 am local time.)

Bright Stars Roundup

The first stars to appear in late August evenings are the bright, white stars of the Summer Triangle asterism - Vega, Deneb, and Altair. At dusk, they are high in the eastern sky and pass the zenith at about 11 pm local time. This annual feature of the summer sky will remain visible until the end of December! At magnitude 0.03, Vega is the brightest star in the summer sky, mainly due to its relative proximity to the sun of only 25 light-years. Altair is only 17 light-years from the sun, but Deneb is a staggering 2,600 light-years away; so bright because of its far greater inherent luminosity. 

Stars shine with a colouration that is produced by their surface temperatures, and this is captured in their spectral classification. Our sun is a yellowish G-class star with a surface temperature of 5,800 K. The three bright stars of the Summer Triangle are A-class stars that appear blue-white to the eye and have high surface temperatures in the range of 7,500 to 10,000 K. Look in the western sky for orange Arcturus, a K-class giant star with a temperature of only 4,300 K. Sitting low in the southwest, reddish Antares, the heart of Scorpius, is an old M-class star with a surface temperature of 3,500 K. By comparing these stars colours’ to other stars, you can estimate those stars’ temperatures.

Keep looking up to enjoy the sky! I love getting questions so, if you have any, send me a note.

[astrogeoguy]

The Perseids Peak over Sunday Night, the Moon Returns to Grace the Eve, Jupiter Sports Twin Spots, and the Demon Star Revives!

(Above: The path of Comet 21P/Giacobini-Zinner in the northeastern sky this week. It will be passing Casssiopeia heading downwards, shown here at 11 pm local time.)

Astronomy Skylights for this week (from August 12th, 2018) by Chris Vaughan. (Feel free to pass this along to friends and send me your comments, questions, and suggested topics.) I post these with photos at http://astrogeoguy.tumblr.com/ where the old editions are archived. You can also follow me on Twitter as @astrogeoguy! Unless otherwise noted, all times are Eastern Time. Please click this MailChimp link to subscribe to these emails. If you are a teacher or group leader interested joining me on a guided field trip to York University’s Allan I. Carswell Observatory, or another in your area, visit www.astrogeo.ca.

If you’d like me to bring my Digital Starlab inflatable planetarium to your school or other daytime or evening event, visit DiscoveryPlanetarium.com and request me. We’ll tour the Universe together!

My latest column for Space.com is all about this week’s Mars opposition and closest approach. You can find it here.

My latest Mobile Astronomy column for Space.com is about the Perseid meteor shower. You can find it here. 

Public Events

Taking advantage of the moon, Venus, Jupiter, Saturn, Mars, and other bright objects in the sky this week, the RASC Toronto Centre astronomers will hold their free monthly public City Sky Star Party in Bayview Village Park (steps from the Bayview subway station), around 8 pm on the first clear weeknight this week (except Wed and Fri). You don’t need to be an RASC member, or own any equipment, to join them. Check here for details, and check the banner on their website home page or Facebook page for the GO or NO-GO decision around 5 pm each day. 

Every Monday evening, York University’s Allan I. Carswell Observatory runs an online star party - broadcasting views from four telescopes/cameras, answering viewer questions, and taking requests! Details are here. On Wednesday evenings after dark, they offer free public viewing through their telescopes. If it’s cloudy, the astronomers give tours and presentations. Details are here. 

Teachers! The York University Astronomy department will hold Astro Workshop 2018, professional development for teachers, on August 14-16, 2018. Registration and details are here. 

At 7:30 pm on Wednesday, August 15, the RASC Toronto Centre will hold their free monthly Recreational Astronomy Night Meeting at the Ontario Science Centre. The public are welcome. Talks include the Sky This Month, measuring double stars, and making your own Pluto images from free science mission data. Check here for details. Parking is free. 

At 6:30 pm on Tuesday, August 14, the S Walter Stewart Library will host a free public lecture by Dr. Renée Hložek of the Dunlap Institute at U of T (she’s fantastic!). It’s entitled The Big, Dark and Beautiful Universe. Check here for details. 

At 8:30 pm on Wednesday, August 15, the High Park Nature Centre will host a free public Urban Bat Walk followed by stargazing (weather permitting). Check here for details. 

Eastern GTA sky watchers are invited to join the RASC Toronto Centre and Durham Skies for solar observing and stargazing at the edge of Lake Ontario in Millennium Square in Pickering on Friday evening, August 17, from 6 pm to 11 pm. Details are here. If it’s cloudy, they’ll try again on Saturday. Before heading out, check the RASCTC home page for a Go/No-Go call in case it's too cloudy to observe. 

On Friday, August 17 at 8 pm, adults can enjoy some suds with their science at Astronomy on Tap T.O. at the Great Hall, a free event hosted by the U of T Astronomy Department. Talks, trivia, contest giveaways, and more! Details are here. 

The next RASC Public Event at the David Dunlap Observatory will be on Saturday, August 18. There will be sky tours in the Skylab planetarium room, space crafts, a tour of the giant 74” telescope, and viewing through lawn telescopes (weather permitting). The doors will open at 7:30 pm for an 8 pm start. Attendance is by tickets only, available here. If you are a RASC member and wish to help us at DDO in the future, please fill out the volunteer questionnaire here. And to join RASC, visit this page. 

The Perseid Meteor Shower Peaks Tonight!

Overnight tonight (Sunday) the spectacular annual Perseid Meteor Shower will reach its peak, when the most meteors will be seen per hour. After tonight, the shower will taper off until it officially ends on August 26, so you should head out on Monday night if it’s clear, and continue to keep an eye out for bright meteors for the rest of this week, although the moon will increasingly affect seeing conditions. I wrote details about how meteor showers work here last week. Make an effort to see this show; next year the Full Moon will spoil the Perseid peak. 

For best results, try to find a safe and very dark viewing location with as much open sky as possible. Even a 30 minute drive to a park or rural site away from big city light pollution will help a lot. You can start watching as soon as it is dark - to catch very long meteors produced by particles skimming the Earth’s upper atmosphere. These are rarer, but feature very long trains. Don’t worry about watching the radiant. Meteors from that position will be heading directly towards you and have very short trails. 

Bring a blanket for warmth and a chaise to avoid neck strain, plus snacks and drinks. Try to keep watching the sky even when chatting with friends or family – they’ll understand. Call out when you see one; a bit of friendly competition is fun! 

Don’t look at your phone or tablet – the bright screen will spoil your dark adaptation. If you can, minimize the brightness or cover the screen with red film. Disabling app notifications will reduce the chances of unexpected bright light, too. And remember that binoculars and telescopes will not help you see meteors because they have fields of view that are too narrow. I posted some diagrams here. Good hunting! 

The Moon and Planets

After reaching its new phase on Saturday, the young crescent moon will return to grace the low western evening sky for a short time after sunset tonight (Sunday). For the rest of the week, it will wax and slide east, lingering longer after sunset each evening. 

In the western sky on Tuesday evening, the moon will take up a position a palm’s width above bright Venus, making a lovely wide field photo opportunity. On Wednesday evening it will sit a similar distance above the bright white star Spica in Virgo (the Maiden). On Thursday and Friday, the moon will hop over Jupiter, moving from the planet’s upper right to its upper left. Using the moon as a starting point, you might be able to spot Jupiter in daylight using binoculars.

(Above: The moon and Jupiter in daylight at 7 pm EDT on August 16. The following day, the moon will hop to Jupiter’s upper left. The orange circle represents a binoculars field of view.)

This is the best week of the moon’s monthly orbit to view it in binoculars or a telescope. The moon waxes because the sun is slowly rising over its eastern horizon. The shallow angle of the sunlight casts deep black shadows all along the terminator line – the boundary between the lit and unlit hemispheres. New terrain will be showcased every night! 

Extremely bright Venus will still blaze away in the western evening sky this week – and it’s still brightening! On Thursday, Venus will reach its widest angle east of the sun. After that, the planet will begin to swing back towards a meeting with the sun in October. The descending evening ecliptic is pulling Venus a bit lower each night, but we can observe it until about 10 pm local time. In a small telescope, the planet’s disk will resemble a first quarter moon, half-lit on the sunward side (although your telescope might flip the view).

(Above: Venus reaches greatest elongation east of the sun on August 16, after which it will start to swing back towards the sun. Meanwhile the moon will look upon Jupiter as it passes close above the bright double star Zubenelgenubi,as shown here for 9 pm local time.)

We only have a few more good weeks to enjoy Jupiter this year. This week, the very bright planet will be in the southwestern sky after dusk, and then set in the west-southwest at about 11:30 pm local time. Jupiter has been slowly shifting eastwards. In the middle of this week, it will pass close above a nearby bright star. Afterwards it will start to pull away. The star is Zubenelgenubi, the brightest star in Libra (the Scales). In binoculars, you’ll plainly see that Zubenelgenubi is a pair of stars. While you have the binoculars handy, see if you can see Jupiter’s four Galilean moons (Io, Europa, Callisto, and Ganymede) flanking the planet. 

From time to time, the small round black shadows cast by Jupiter’s four Galilean moons become visible in backyard telescopes as they cross (or transit) the planet’s disk. On Thursday, August 16, Europa’s shadow will begin to transit at 7:56 pm EDT (in evening twilight). At 8:05 pm EDT, Io’s shadow will join Europa’s and the duo will transit Jupiter until they both move off the planet at 10:10 pm. A reasonable backyard telescope will show the black shadows, but a very good telescope is needed to see the moons themselves. More shadow transits are available in other time zones around the world, including some double shadow ones.

 (Above: A double shadow transit caused by Europa and Io will occur on Jupiter on Thursday, August 16, as shown here at 9:15 pm EDT.)

The Great Red Spot (or GRS, for short) takes about three hours to cross Jupiter’s disk. But the planet’s 10-hour rotation period (i.e., its day) means that the spot is only observable from Earth every 2-3 nights. If you’d like to see the GRS, use a medium-sized telescope (or larger). You’ll have your best luck on evenings with steady air – when the stars are not twinkling too much. Try to look within an hour before or after the following times: Sunday, August 12 at 8:57 pm, Tuesday, August 14 at 10:36 pm, Friday, August 17 at 8:07 (in twilight), and Sunday, August 19 at 9:46 pm. All times are given in Eastern Daylight Time (EDT), so adjust for your local time zone. 

Around 9 pm local time, when the first bright stars appear overhead, medium-bright Saturn will appear not too high up the darkening southern sky. The yellow-tinted planet will reach its highest elevation of about 2 fist diameters above the southern horizon at around 9:30 pm, and then descend to set in the west at about 2:30 am. This summer, the ringed planet has been on the eastern (left-hand) outskirts of the Milky Way, and situated just above the “lid” star of the Teapot-shaped constellation of Sagittarius (the Archer). As the sky darkens, even a small telescope should be able to show you some of Saturn’s larger moons, especially Titan. Using a clock’s dial analogy, Titan will move counter-clockwise this week from a position at 12 o’clock (above the planet) to 7 o’clock (to the lower left of it). (Remember that your small telescope might flip and/or invert the view. Use the moon to find out how your telescope changes things.) 

Mars will still be very bright and close to Earth this week. Visually, it will appear pink or orangey. It will rise over the southeastern horizon at around 8 pm local time (give or take, depending on your latitude) and then climb higher until midnight local time, when it will reach an elevation of about 20° (or two outstretched fist diameters) above the southern horizon. (That will be the best hour to view the planet in a telescope because it will then be shining through the least amount of Earth’s distorting atmosphere.) Note that 20° is lower than many trees and buildings, so a clear southern vista is essential.

(Above: Mars and Saturn dominate the overnight southern sky, as shown here for 10 pm local time this week. Tiny Pluto sits near Sagittarius, between the two naked-eye planets.) 

At visual magnitude 5.8, blue-green coloured Uranus is visible from late evening until dawn. You can see it without optical aid under very dark skies, or in binoculars and telescopes under moderately light-polluted skies. The ice giant planet is located in the eastern sky, about 4.5 finger widths to the left of the modestly bright star Torcular (Omega Piscium), which is above the “V” where the two starry cords of Pisces (the Fishes) meet.

(Above: The detailed positions of Uranus and Neptune in August, 2018.) 

Using a decent quality telescope this week, you can see the distant and very blue planet Neptune among the dim stars of Aquarius (the Water-bearer). It will rise in the east shortly after 9 pm local time. Look for the magnitude 7.8 planet sitting 1.75 finger widths to the right of the modestly bright star Phi (φ) Aquarii and 4 finger widths to the left of the brighter star Hydor (Lambda Aquarii). 

At 1:36 am EDT on Wednesday, August 15, distant dwarf planet Pluto will pass in front of, or occult, a dim distant star. The planet is positioned roughly midway between Mars and Saturn. Many serious astronomers will try to record the event to study how Pluto’s atmosphere dims the star.  

A Binocular Comet

Comet 21P/Giacobini-Zinner has been gradually brightening for some time because it is approaching Earth’s orbit. This week, you should be able to see the faint fuzzy object in binoculars or a small telescope, if you can escape city lights. The comet will be heading downwards every night past the bright star Segin, which marks the bottom-most star in the “W” of Cassiopeia (the Queen).

(Above: This animation was assembled from a series of 55 images of Algol taken with the CHARA interferometer at Mount Wilson Observatory, using the infrared part of the spectrum (coloring the normally white star red). It shows the dimmer companion star orbiting Algol and passing in front of it - a classic eclipsing binary star system. The numerical labels range from 0.0 at the start of the orbit, to 0.868, near the end of the orbit.) 

See the “Demon” Star Brighten

The “Demon Star”, more formally known as Algol, is a star that is easy to see using unaided eyes. In Perseus (the Hero), it is among the most accessible variable stars for beginner skywatchers. Despite the connotation of its nickname (it represents the severed head of Medusa the Gorgon being held by Perseus), the star is a hot white star located 92 light-years from Earth.

Algol’s brightness dims noticeably for about 10 hours once every 2 days, 20 hours, and 49 minutes because a dim companion star orbiting nearly edge-on to Earth crosses in front of the much brighter main star – an arrangement that is called an eclipsing binary star system. On Saturday, August 18 at 9:32 pm EDT, Algol will reach its minimum brightness of magnitude 3.4 and will sit just above the northeastern horizon. By 2:30 am EDT, it will be halfway up the eastern sky and will have brightened to its usual magnitude of 2.1. The dimming periods can fall at any time of the day or night. The timing of this particular event makes watching the return to brightness a convenient project for evening observers.

Keep looking up to enjoy the sky! I love getting questions so, if you have any, send me a note.

[astrogeoguy]

The Full Milk Moon precedes June, and Many Pretty Planet Pairings!

(Above: In this image taken on March 31, 2012 by Damien Peach, yellowish Saturn at top and reddish Mars at centre, hold court over the spectacular, distant globular cluster Messier 22. This week, Saturn alone guards the distant deep sky object. NASA APOD April 12, 2012)

Astronomy Skylights for this week (from May 27th, 2018) by Chris Vaughan. (Feel free to pass this along to friends and send me your comments, questions, and suggested topics.) I post these with photos at http://astrogeoguy.tumblr.com/ where the old editions are archived. You can also follow me on Twitter as @astrogeoguy! Unless otherwise noted, all times are Eastern Time. Please click this MailChimp link to subscribe to these emails. If you are a teacher or group leader interested joining me on a guided field trip to York University’s Allan I. Carswell Observatory, or another in your area, visit www.astrogeo.ca.

If you’d like me to bring my Digital Starlab inflatable planetarium to your school or other daytime or evening event, visit DiscoveryPlanetarium.com and request me. We’ll tour the Universe together!

Public Events

On Monday evenings, York University’s Allan I. Carswell Observatory runs an online star party - broadcasting views from four telescopes/cameras, answering viewer questions, and taking requests! Details are here. On Wednesday evenings after dark, they offer free public viewing through their telescopes. If it’s cloudy, the astronomers give tours and presentations. Details are here. 

On Thursday, May 31 from 11 am to 1:15 pm, join Dr. Kim Tait, Teck Endowed Chair of Mineralogy at The Royal Ontario Museum for Journey to Mars: Rocks, Rovers, Results and the ROM. It’s free with ROM admission, and registration and details are here. 

If it’s sunny on Saturday morning, June 2 from 10 am to noon, astronomers from the RASC Toronto Centre will be setting up outside the main doors of the Ontario Science Centre for Solar Observing. Come and see the Sun in detail through special equipment designed to view it safely. This is a free event (details here), but parking and admission fees inside the Science Centre will still apply. Check the RASC Toronto Centre website or their Facebook page for the Go or No-Go notification. 

After a long period of inactivity, I’m pleased to announce that the David Dunlap Observatory will re-open for public events starting this Saturday night, June 2! Kicking off the season will be Professor Paul Delaney of York University talking about The Search for Planet 9, all about Pluto and the objects beyond it. Tickets and registration can be found online here. If you would like to volunteer at the observatory, contact me and I’ll connect you.

Asterisms Abound

If you missed last week’s tour of the many Asterisms in the night sky, I posted sky charts with the asterisms labelled here.

The Moon and Planets

Tonight, Sunday evening, the very bright waxing gibbous (nearly full) moon will start a tour of the major planets – landing less than a palm’s width to the left of Jupiter and accompanying it as it crosses the sky all night. Look for the pair of objects in the southeastern sky after dusk. 

On Monday evening, the moon will hop east to appear a fist’s width above the bright orange-red star Antares, “the Rival of Mars” in Scorpius (the Scorpion). The moon never ventures too far from the zodiac constellations because its orbit is tilted only 5° from the ecliptic, the imaginary circle that defines the 13 zodiac constellations. Yes! I said 13. Annually during the first half of December, the sun passes across the foot of Ophiuchus (the Serpent-Bearer). Maybe he’s trying to trip Ole Sol!

(Above: The sun’s path along the ecliptic, as indicated by the green line, carries it through the 13th zodiac constellation, Ophiuchus, in December every year. This week, the moon will hop over Ophiuchus’ foot, as shown here for 10:45 pm local time on Monday, May 28.)

On Tuesday morning at 10:20 am EDT, the moon will reach a point opposite the sun in the sky, triggering its full moon phase. The full moon of May, known as the Full Milk Moon, Full Flower Moon, or Full Corn Planting Moon, always shines in or near the stars of Libra (the Scales). To unaided eyes, the moon will look full on Monday night, and still look full when it rises on Tuesday at sunset. But binoculars or a telescope will reveal shadows in craters along only its left edge on Monday and along its right edge on Tuesday. 

Look for a medium-bright star sitting a few finger widths to the upper left of the full moon in the southeastern sky during late evening on Tuesday. That star, named Sabik, marks the knee of our friend Ophiuchus! On Wednesday evening, the moon will hop over Ophiuchus’ leg, putting Sabik about a fist’s diameter to the moon’s upper right.

(Above: This week, the moon’s eastward orbital motion along the ecliptic, as shown here at 11:45 pm local time on Wednesday, May 30, carries it past Saturn and Mars.)

Also overnight on Wednesday, the moon will be situated a fist’s diameter to the upper right of yellowish Saturn. Then on Thursday evening at about 10:45 pm local time, the now waning gibbous moon will rise in the east with Saturn. The moon will sit only two finger widths to the left of the ringed planet and both objects will fit easily within the field of view of binoculars. 

Saturn is sitting near three deep sky Messier objects this week. (If you wait a few days for the moon to pass out of the sky, you’ll have better luck seeing them.) Messier 25, an open star cluster 2,000 light-years away and nearly as broad as the full moon, will be sitting a few finger widths to the upper left of Saturn. Messier 22, a globular star cluster nearly ten thousand light-years away, will be two finger widths below Saturn. And Messier 28, another globular star cluster that is almost 18,000 light-years distant, will be three finger widths to the right, and below, Saturn. You should be able to see Saturn itself until almost 5:30 am local time, when it will sit about 1.5 fist widths above the southwestern horizon.

(Above: A close up view of the Moon - Saturn encounter on May 31. The three deep sky objects, Messier 22, Messier 25, and Messier 28 will remain in place once the moon departs the area. Binoculars will show a field of view similar to the orange circle.)

Wrapping up the moon’s tour, low in the southeastern sky between 1 am local time and dawn on the morning of Sunday, June 3, the waning gibbous moon will sit a few finger widths above bright reddish Mars. Both objects will fit into the field of view of binoculars. Mars, now noticeably brighter than Saturn, continues to steadily brighten and increase in size as the Earth’s faster orbit brings us closer to the red planet this summer. (We will pass it on the “inside track” in late July.) 

(Above: The moon will meet Mars on the morning of Sunday, June 3, as shown here for 2 am local time.)

Venus continues to gleam in the western evening sky this week as it climbs away from the sun. The planet sets at about 11:30 pm local time. Tonight (Sunday), our sister planet will end up extremely close to a yellow, modestly-bright star named Mebsuta which marks the waist of Castor, the westerly twin. Both objects will fit into the field of view of a small telescope. You can observe Venus drawing away from Mebsuta on each subsequent evening.

(Above: Brilliant Venus will pass close to the much fainter yellow star Mebsuta in Gemini on Sunday, May 27, as shown here for 10:35 pm local time.) 

Jupiter is still visible all night long this week. Look for it as a very bright object in the southeastern sky after dusk. It will reach its highest elevation (about three fist diameters) above the southern horizon around midnight local time, and then descend into the southwestern horizon before the sun rises. The bright star sitting just to the right of Jupiter is Libra’s (the Scales) brightest star, Zubenelgenubi. In binoculars or a small telescope, it splits into a closely spaced pair of stars. 

On Wednesday, May 30 between 11:07 pm and 1:17 am, the black shadow of Jupiter’s moon Io and its little round black shadow will cross (or transit) Jupiter’s disk. A reasonable backyard telescope will show the black shadows, but a very good telescope is needed to see the moons themselves. 

The Great Red Spot takes about three hours to cross Jupiter’s disk. But the planet’s 10-hour rotation period (i.e., its day) means that the spot is only observable from Earth every 2-3 nights.  If you’d like to see the GRS, use a medium-sized telescope (or larger). You’ll have your best luck on evenings with steady air – when the stars are not twinkling too much. The best times to try this week are: Sunday, May 27 at 10:10 pm, Tuesday, May 29 at 11:49 pm, Friday, June 1 at 9:19 pm, and Sunday, June 3 at 10:57 pm. All times are given in Eastern Daylight Time (EDT), so adjust for your local time zone. Try to look within an hour before or after the times I’ve given. 

Distant blue Neptune, still among the modest stars of Aquarius (the Water-bearer), has become observable in telescopes in the pre-dawn eastern sky after it rises about 2:15 am local time. I’ll post sky charts for the observable planets here.

Keep looking up to enjoy the sky! I love getting questions so, if you have any, send me a note.

[astrogeoguy]

It’s Easy to See Ceres, the Full Strawberry Moon meets Mars after Saturn, and the Ringed Planet Peaks for 2018!

(Above: On Wednesday, June 27, Saturn reaches its closest and brightest point for this year. That same night, the full moon will sit just above it. Many spectacular deep sky objects sit around Saturn, and are better seen once the moon moves away. Look for the large, bright open cluster designated M24 sitting above Saturn all summer.)

Astronomy Skylights for this week (from June 24th, 2018) by Chris Vaughan. (Feel free to pass this along to friends and send me your comments, questions, and suggested topics.) I post these with photos at http://astrogeoguy.tumblr.com/ where the old editions are archived. You can also follow me on Twitter as @astrogeoguy! Unless otherwise noted, all times are Eastern Time. Please click this MailChimp link to subscribe to these emails. If you are a teacher or group leader interested joining me on a guided field trip to York University’s Allan I. Carswell Observatory, or another in your area, visit www.astrogeo.ca.

If you’d like me to bring my Digital Starlab inflatable planetarium to your school or other daytime or evening event, visit DiscoveryPlanetarium.com and request me. We’ll tour the Universe together! 

Public Events

On Monday evenings, York University’s Allan I. Carswell Observatory runs an online star party - broadcasting views from four telescopes/cameras, answering viewer questions, and taking requests! Details are here. On Wednesday evenings after dark, they offer free public viewing through their telescopes. If it’s cloudy, the astronomers give tours and presentations. Details are here. 

On Friday, June 29, starting at 7 pm, the U of T AstroTour will present their planetarium show entitled Grand Tour of the Cosmos. Tickets and details are here. 

The next RASC Family Night at the David Dunlap Observatory will be on Saturday, July 7. There will be sky tours in the Skylab planetarium room, space crafts, a tour of the giant 74” telescope, and viewing through lawn telescopes (weather permitting). The doors will open at 8:30 pm for a 9 pm start. Attendance is by tickets only, available here. If you are a RASC member and wish to help us at DDO in the future, please fill out the volunteer questionnaire here. And to join RASC, visit this page. 

The Moon and Planets

To begin this week, the moon will be shining brightly in the evening sky as a nearly full (waxing gibbous) globe. Remember to pull out your binoculars or small telescope and look along the boundary separating the lit and dark sides. That’s where the most dramatic moonscapes are. Because the moon reaches its full phase on Thursday at 12:53 am EDT, the moon will look full on Wednesday evening and slightly past full on Thursday night.

(Above: The full Strawberry moon is nick-named for the bounty of Mother Nature in June annually.) 

The June full moon, colloquially known as the Strawberry Moon, Mead Moon, Rose Moon, or Hot Moon, always shines in or near the stars of southern Ophiuchus (the Serpent-Bearer). Because the moon reaches full when it is opposite the sun in the sky, full moons always rise in the east as the sun sets, and set in the west at sunrise. Since vertically impinging sunlight casts no shadows on a full moon, all of the surface brightness variations are generated by differences in the reflectivity, or albedo, of the lunar surface rocks. 

In the southeastern sky after dusk on the Wednesday evening, the full moon will sit one finger’s width above bright, yellowish Saturn. The two objects will cross the sky together during the night and will easily fit within the field of a small telescope at low magnification. Meanwhile, the moon’s separation from Saturn will noticeably increase as the moon slides eastward in its orbit during the night. 

The large open star cluster called Messier 24 will sit a few finger widths above (to the northeast of) the moon and Saturn. The cluster, also known as the Small Sagittarius Star Cloud, is three times wider than the moon! Try to see it using binoculars, or wait for the moon to move away on the following nights and use Saturn to find it then. 

After mid-week, the moon will slide east, rise later, and begin to wane – with the dark region growing on the moon’s western (our right-hand) side. About 11 pm local time on Saturday night, bright red Mars will rise in the east with the waning gibbous moon shining 4 finger widths to the upper left (northeast) of it. Both objects will fit into the field of view of binoculars. By dawn, the pair will appear low in the southwestern sky.

(Above: The inner planets Mercury and Venus continue to put on a good show this week, as shown here for 9:30 pm local time on Sunday, June 24. Mercury will fade and descend next week, while Venus will continue to brighten.) 

Venus continues to catch our eye in the western evening sky this week while it continues to swing away from the sun - and it will still get brighter! The planet will be setting at about 11:30 pm local time all week because it is travelling east while the entire sky is shifting west, holding it in place. Venus is gradually growing larger as it moves towards Earth. In a small telescope, the planet’s disk will not look round. Instead, it will exhibit a gibbous (70% illuminated) phase. 

This is the best week to see elusive Mercury sitting low over the northwestern horizon for a brief period after sunset. It recently peaked in brightness and the best time to look is between 9:45 and 10:15 pm local time. You’ll need a low open horizon because the planet will be only a few finger widths above the horizon (or less). 

Jupiter is the bright object you will see shining brightly in the southern sky after dusk this week. Around that time, it will be at its highest elevation (about three fist diameters) above the southern horizon. Over the following five hours, it will move west and descend – setting in the west-southwest about 3 am local time. Once it’s dark enough, look for a bright star sitting just to the lower left of Jupiter. That’s Zubenelgenubi, the brightest star in Libra (the Scales). In binoculars or a small telescope, it splits into a closely separated pair of stars.

(Above: On Monday, June 25, the shadow of Jupiter’s moon Ganymede will transit the northern zone of the planet, along with the Great Red Spot, as simulated here at 10 pm EDT.)  

On Monday, June 25, and visible between 9 pm (in twilight) and 10:42 pm EDT, the little, round, black shadow of Jupiter’s moon Ganymede will cross (or transit) near the north pole of Jupiter’s disk. On Saturday, June 30 starting at 1:14 am and visible until Jupiter sets, the shadow of Jupiter’s moon Io will transit. A reasonable backyard telescope will show the black shadows, but a very good telescope is needed to see the moons themselves. More shadow transits are available in other time zones around the world. 

The Great Red Spot (or GRS, for short) takes about three hours to cross Jupiter’s disk. But the planet’s 10-hour rotation period (i.e., its day) means that the spot is only observable from Earth every 2-3 nights. If you’d like to see the GRS, use a medium-sized telescope (or larger). You’ll have your best luck on evenings with steady air – when the stars are not twinkling too much. The best times to try this week are: Monday, June 25 at 1:18 am and again at 9:09 pm (in twilight, with a Ganymede shadow bonus), Wednesday, June 27 at 10:48 pm, and Saturday, June 30 at 12:27 am. All times are given in Eastern Daylight Time (EDT), so adjust for your local time zone. Try to look within an hour before or after the times I’ve given.

(Above: Look for Saturn above the Teapot-shape of Sagittarius all summer. On opposition night, June 27, the full moon will join the party, as shown here at 11 pm local time.)

On Wednesday, the Earth’s orbit will carry us between Saturn and the sun. Sitting opposite the sun in the sky (a term that astronomers call opposition), Saturn will be visible all night long, and the planet’s disk will be the brightest and largest (18 arc-seconds) for the year. Planets don’t emit their own light. We see them because the sun’s light has travelled all the way out to them and reflected off their surfaces. At opposition, the reflected light from Saturn will travel for 75 minutes to reach Earth – and our human eyes. 

Yellow-tinted Saturn will rise in the southeastern sky at about 9 pm local time this week, just as the sun sets. The ringed planet will be spending the summer of 2018 just to the left of the Milky Way, and just above the Teapot-shaped stars that form Sagittarius (the Archer). Saturn moves over the southern horizon, its highest point in the sky at 1:30 am local time. It will remain visible until about 5 am local time, when it will sit more than a fist’s width above the southwestern horizon. Scientists have recently determined that Saturn’s reflective icy rings formed only a few hundred million years ago – during Earth’s Carboniferous Period, when early dinosaurs roamed our planet! 

(Above: Mars rises well after Saturn, but still before midnight, as shown here on June 27 at 11 pm local time.)

Mars is getting good now! The Red Planet will be rising in the east just after 11 pm local time this week. Mars will continue to steadily brighten and increase in apparent size (when viewed through a telescope) as the Earth’s faster orbit brings us closer to the red planet until July 31. Mars will reach its highest position, over the southern horizon, around 3:30 am local time, and then remain visible until just after 5 am. 

Distant blue Neptune, among the modest stars of Aquarius (the Water-bearer), is observable in telescopes in the eastern sky after it rises around 13:30 am local time. This week, look for the magnitude 7.9 planet sitting one finger width to the right of the naked eye star Phi (φ) Aquarii and about five finger widths to the left of brighter Hydor (Lambda Aquarii). 

Blue-green coloured Uranus is visible in binoculars, if you know where to look. It, too, is in the eastern pre-dawn sky, located about four finger widths to the left of the modestly bright star Torcular, which is down toward the “V” where the two cords of Pisces (the Fishes) meet. I posted sky charts for Uranus and Neptune here. 

It’s Easy to See Asteroids - Sometimes

Here’s a very easy way to see an asteroid with your own eyes. After dusk on the evening of Wednesday, June 27, the large dwarf planet (formerly asteroid) Ceres will sit only 9 arc-minutes (or less than one third of the moon’s apparent diameter) above the bright, visible double star Algieba in Leo (the Lion). Algieba marks the throat of the lion, midway along the backwards question-mark that forms the front of the constellation. After dusk, the lion will be positioned over the western horizon and tipped with his face downward to the right. I’ll post a sky chart here. 

(Above: Thursday, June 27 brings the perfect chance to see the dwarf planet Ceres when it passes very closely above the naked-eye double star Algieba in Leo the lion. Use binoculars and small telescopes on the double star and look for a small object just above it. The sky is shown for 10:30 pm local time.)

Use binoculars to look for Ceres as a little, star-like object just a short distance above Algieba. A small telescope at medium-high magnification will show Ceres and Algieba’s close-together pair of distant stars together in the same field of view.

(Above: A detailed view of the region around Algieba and Ceres on June 27. The yellow circle represents the field of view of a medium power telescope.) 

After a determined search by many astronomers who were looking for a theorized missing planet, Ceres was the first asteroid ever discovered, by Giuseppe Piazzi in Palermo, Sicily, on January 1, 1801. It was named after the Roman Goddess of Agriculture. (The same name gave us the word “cereal”!) Ceres was originally given planet status, orbiting as it does between Mars and Jupiter. But calculations of its 950 km diameter, and later discoveries of countless additional bodies in the asteroid belt, led to its demotion to queen of the asteroid belt. But in 2006, the same rules that demoted Pluto to dwarf planet status promoted Ceres to the same class of objects. Good luck! 

(Above: The path of the large asteroid Vesta (red line) over the month surrounding June 19, when it reached peak brightness, within range of binoculars. The sky is shown at 10:30 pm local time.)

As I mentioned last week, another asteroid, the minor planet (4) Vesta, is now visible all night long, and appearing about its brightest (magnitude 5.33) for the year - within reach of binoculars and small telescopes. Look for the object above the Teapot-shaped constellation Sagittarius (the Archer), about a fist’s diameter to the upper right of Saturn.

Keep looking up to enjoy the sky! I love getting questions so, if you have any, send me a note.