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The Fate of the Universe

Ok so the title this time is a bit dramatic. I’ll give you that. But who doesn’t love a little drama here and there?!

So the universe is expanding. What exactly does that mean long term? Where are we headed? What’s next for our universe?

So first of all, the current estimate for the age of the universe is about 13.8 billion years. This can be determined basically by “winding back the clock” on the data we know now. Since we know how fast we are expanding today and how much that expansion is accelerating, we can use that data to model where it all began.

Where we’re headed is a little more ominous. Basically, many scientists believe that evidence points to this expansion kind of just continuing for the foreseeable future. If we were alive for long enough (and if Earth somehow escaped the eventual firey death of the sun), we eventually wouldn’t really have any neighbors to speak of. Scary thought. I for one am glad I won’t be around to see that.

Anyways, that’s all for today. As always, stay spacey!

Sources: https://www.space.com/33892-cosmic-microwave-background.html

https://wmap.gsfc.nasa.gov/universe/uni_fate.html

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HAPPY BIRTHDAY CURIOSITY!

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Opportunity Emerges in a Dusty Picture via NASA https://ift.tt/2OSaTC8

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Splashdown! Apollo 7 Returns Home via NASA https://ift.tt/2PO9Mnu

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The Big Bang Theory (not the show)

The Big Bang theory is a term that gets thrown around all the time (especially with the show being so popular). But what exactly is it?

Basically, the universe used to be really really small. Like, so small that all of it was all actually contained in one very small point, and then all of a sudden it just kind of ejected outward all the matter that makes up the great expanse we know and love. Which sounds crazy. So why do we think that?

It comes down to background radiation. Basically, we can still hear the echo of that boom today. It was predicted in the 1940’s, but two astronomers named Arno Penzias and Robert Wilson were the first to actually observe it. The story goes that these two men were hearing an annoying static in the measurements they were taking, and eventually, after crossing every other possible explanation for the crackle off the list, it became clear that it must be cosmic background radiation.

Wild how an annoying problem like staticky data can turn into one of the most important discoveries of the century!

That’s all for today. As always, stay spacey!

Source: https://www.space.com/33892-cosmic-microwave-background.html

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This composite of the giant barred spiral galaxy NGC 6872 is 522,000 light-years across, making it about five times the size of the Milky Way. by __hrga__

★☆★ SPACE ★☆★

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NGC 6334, Cat’s Paw

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Hubble’s Law

Next topic of discussion: Hubble’s law. AKA, how exactly can we be sure the universe is expanding?

The answer lies with Hubble (yes, that same Hubble with the big space telescope). Hubble’s law is as follows:

What all that boils down to is a couple of key things:

Firstly, things in space that are far away from us exhibit redshift. This all comes down to the Doppler effect. If you’ve ever heard that NEEEYYYYOOOOOOM sound a fast car makes when passing you, that’s a perfect example. The idea is that things that are coming towards you sound more and more high pitched(since the sound is being compressed), and then as soon as they pass, they get progressively lower in pitch(since the sound is sort of stretched out) . Turns out the same thing happens with light. Things that are moving away from you get redder(longer wavelengths) since the light waves get stretched out, and things getting closer look a bit bluer(shorter wavelengths) since the light coming from them is being compressed. So we have an answer!!! We can tell the universe is expanding because pretty much everything we can observe is ever so slightly redder than it should be, and red = moving away.

Secondly, Hubble observed that objects that are farther away from us already are the ones moving the fastest; in fact, the Doppler-shift observed of celestial bodies is just about proportional to the distance they are from the earth. This means that things farther from us look noticeably more redshifted than the things more in our neighborhood.

It’s also worth noting that just because everything is moving away from us we do not get to say we are the center of the universe. Think of it less like everything is simply shooting away from us, and more like the spaces between everything are just kind of getting bigger. Here’s a cool animation to help illustrate that if it still doesn’t quite make sense:

https://www.exploratorium.edu/origins/hubble/tools/center.html

Turns out Hubble was a pretty impressive astronomer, and totally 100% deserves to be a name we all know-- and not just because of his namesake telescope.

That’s all for today. As always, stay spacey!

Sources: http://astronomyonline.org/Science/HubbleLaw.asp

https://www.exploratorium.edu/origins/hubble/tools/center.html

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NGC 289: Swirl in the Southern Sky : About 70 million light-years distant, gorgeous spiral galaxy NGC 289 is larger than our own Milky Way. Seen nearly face-on, its bright core and colorful central disk give way to remarkably faint, bluish spiral arms. The extensive arms sweep well over 100 thousand light-years from the galaxy’s center. At the lower right in this sharp, telescopic galaxy portrait the main spiral arm seems to encounter a small, fuzzy elliptical companion galaxy interacting with enormous NGC 289. Of course the spiky stars are in the foreground of the scene. They lie within the Milky Way toward the southern constellation Sculptor. via NASA

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A look at the Apollo 17 command module.

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Frozen: Ice on Earth and Well Beyond

Icy Hearts: A heart-shaped calving front of a glacier in Greenland (left) and Pluto’s frozen plains (right). Credits: NASA/Maria-Jose Viñas and NASA/APL/SwRI

From deep below the soil at Earth’s polar regions to Pluto’s frozen heart, ice exists all over the solar system…and beyond. From right here on our home planet to moons and planets millions of miles away, we’re exploring ice and watching how it changes. Here’s 10 things to know:

1. Earth’s Changing Ice Sheets

An Antarctic ice sheet. Credit: NASA

Ice sheets are massive expanses of ice that stay frozen from year to year and cover more than 6 million square miles. On Earth, ice sheets extend across most of Greenland and Antarctica. These two ice sheets contain more than 99 percent of the planet’s freshwater ice. However, our ice sheets are sensitive to the changing climate.

Data from our GRACE satellites show that the land ice sheets in both Antarctica and Greenland have been losing mass since at least 2002, and the speed at which they’re losing mass is accelerating.

2. Sea Ice at Earth’s Poles

Earth’s polar oceans are covered by stretches of ice that freezes and melts with the seasons and moves with the wind and ocean currents. During the autumn and winter, the sea ice grows until it reaches an annual maximum extent, and then melts back to an annual minimum at the end of summer. Sea ice plays a crucial role in regulating climate – it’s much more reflective than the dark ocean water, reflecting up to 70 percent of sunlight back into space; in contrast, the ocean reflects only about 7 percent of the sunlight that reaches it. Sea ice also acts like an insulating blanket on top of the polar oceans, keeping the polar wintertime oceans warm and the atmosphere cool.

Some Arctic sea ice has survived multiple years of summer melt, but our research indicates there’s less and less of this older ice each year. The maximum and minimum extents are shrinking, too. Summertime sea ice in the Arctic Ocean now routinely covers about 30-40 percent less area than it did in the late 1970s, when near-continuous satellite observations began. These changes in sea ice conditions enhance the rate of warming in the Arctic, already in progress as more sunlight is absorbed by the ocean and more heat is put into the atmosphere from the ocean, all of which may ultimately affect global weather patterns.

3. Snow Cover on Earth

Snow extends the cryosphere from the poles and into more temperate regions.

Snow and ice cover most of Earth’s polar regions throughout the year, but the coverage at lower latitudes depends on the season and elevation. High-elevation landscapes such as the Tibetan Plateau and the Andes and Rocky Mountains maintain some snow cover almost year-round. In the Northern Hemisphere, snow cover is more variable and extensive than in the Southern Hemisphere.

Snow cover the most reflective surface on Earth and works like sea ice to help cool our climate. As it melts with the seasons, it provides drinking water to communities around the planet.

4. Permafrost on Earth

Tundra polygons on Alaska’s North Slope. As permafrost thaws, this area is likely to be a source of atmospheric carbon before 2100. Credit: NASA/JPL-Caltech/Charles Miller

Permafrost is soil that stays frozen solid for at least two years in a row. It occurs in the Arctic, Antarctic and high in the mountains, even in some tropical latitudes. The Arctic’s frozen layer of soil can extend more than 200 feet below the surface. It acts like cold storage for dead organic matter – plants and animals.

In parts of the Arctic, permafrost is thawing, which makes the ground wobbly and unstable and can also release those organic materials from their icy storage. As the permafrost thaws, tiny microbes in the soil wake back up and begin digesting these newly accessible organic materials, releasing carbon dioxide and methane, two greenhouse gases, into the atmosphere.

Two campaigns, CARVE and ABoVE, study Arctic permafrost and its potential effects on the climate as it thaws.

5. Glaciers on the Move

Did you know glaciers are constantly moving? The masses of ice act like slow-motion rivers, flowing under their own weight. Glaciers are formed by falling snow that accumulates over time and the slow, steady creep of flowing ice. About 10 percent of land area on Earth is covered with glacial ice, in Greenland, Antarctica and high in mountain ranges; glaciers store much of the world’s freshwater.

Our satellites and airplanes have a bird’s eye view of these glaciers and have watched the ice thin and their flows accelerate, dumping more freshwater ice into the ocean, raising sea level.

6. Pluto’s Icy Heart

The nitrogen ice glaciers on Pluto appear to carry an intriguing cargo: numerous, isolated hills that may be fragments of water ice from Pluto’s surrounding uplands. NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

Pluto’s most famous feature – that heart! – is stone cold. First spotted by our New Horizons spacecraft in 2015, the heart’s western lobe, officially named Sputnik Planitia, is a deep basin containing three kinds of ices – frozen nitrogen, methane and carbon monoxide.

Models of Pluto’s temperatures show that, due the dwarf planet’s extreme tilt (119 degrees compared to Earth’s 23 degrees), over the course of its 248-year orbit, the latitudes near 30 degrees north and south are the coldest places – far colder than the poles. Ice would have naturally formed around these latitudes, including at the center of Sputnik Planitia.

New Horizons also saw strange ice formations resembling giant knife blades. This “bladed terrain” contains structures as tall as skyscrapers and made almost entirely of methane ice, likely formed as erosion wore away their surfaces, leaving dramatic crests and sharp divides. Similar structures can be found in high-altitude snowfields along Earth’s equator, though on a very different scale.

7. Polar Ice on Mars

This image, combining data from two instruments aboard our Mars Global Surveyor, depicts an orbital view of the north polar region of Mars. Credit: NASA/JPL-Caltech/MSSS

Mars has bright polar caps of ice easily visible from telescopes on Earth. A seasonal cover of carbon dioxide ice and snow advances and retreats over the poles during the Martian year, much like snow cover on Earth.

This animation shows a side-by-side comparison of CO2 ice at the north (left) and south (right) Martian poles over the course of a typical year (two Earth years). This simulation isn’t based on photos; instead, the data used to create it came from two infrared instruments capable of studying the poles even when they’re in complete darkness. This data were collected by our Mars Reconnaissance Orbiter, and Mars Global Surveyor. Credit: NASA/JPL-Caltech

During summertime in the planet’s north, the remaining northern polar cap is all water ice; the southern cap is water ice as well, but remains covered by a relatively thin layer of carbon dioxide ice even in summertime.

Scientists using radar data from our Mars Reconnaissance Orbiter found a record of the most recent Martian ice age in the planet’s north polar ice cap. Research indicates a glacial period ended there about 400,000 years ago. Understanding seasonal ice behavior on Mars helps scientists refine models of the Red Planet’s past and future climate.

8. Ice Feeds a Ring of Saturn

Wispy fingers of bright, icy material reach tens of thousands of kilometers outward from Saturn’s moon Enceladus into the E ring, while the moon’s active south polar jets continue to fire away. Credit: NASA/JPL/Space Science Institute

Saturn’s rings and many of its moons are composed of mostly water ice – and one of its moons is actually creating a ring. Enceladus, an icy Saturnian moon, is covered in “tiger stripes.” These long cracks at Enceladus’ South Pole are venting its liquid ocean into space and creating a cloud of fine ice particles over the moon’s South Pole. Those particles, in turn, form Saturn’s E ring, which spans from about 75,000 miles (120,000 kilometers) to about 260,000 miles (420,000 kilometers) above Saturn’s equator. Our Cassini spacecraft discovered this venting process and took high-resolution images of the system.

Jets of icy particles burst from Saturn’s moon Enceladus in this brief movie sequence of four images taken on Nov. 27, 2005. Credit: NASA/JPL/Space Science Institute

9. Ice Rafts on Europa

View of a small region of the thin, disrupted, ice crust in the Conamara region of Jupiter’s moon Europa showing the interplay of surface color with ice structures. Credit: NASA/JPL/University of Arizona

The icy surface of Jupiter’s moon Europa is crisscrossed by long fractures. During its flybys of Europa, our Galileo spacecraft observed icy domes and ridges, as well as disrupted terrain including crustal plates that are thought to have broken apart and “rafted” into new positions. An ocean with an estimated depth of 40 to 100 miles (60 to 150 kilometers) is believed to lie below that 10- to 15-mile-thick (15 to 25 km) shell of ice.

The rafts, strange pits and domes suggest that Europa’s surface ice could be slowly turning over due to heat from below. Our Europa Clipper mission, targeted to launch in 2022, will conduct detailed reconnaissance of Europa to see whether the icy moon could harbor conditions suitable for life.

10. Crater Ice on Our Moon

The image shows the distribution of surface ice at the Moon’s south pole (left) and north pole (right), detected by our Moon Mineralogy Mapper instrument. Credit: NASA

In the darkest and coldest parts of our Moon, scientists directly observed definitive evidence of water ice. These ice deposits are patchy and could be ancient. Most of the water ice lies inside the shadows of craters near the poles, where the warmest temperatures never reach above -250 degrees Fahrenheit. Because of the very small tilt of the Moon’s rotation axis, sunlight never reaches these regions.

A team of scientists used data from a our instrument on India’s Chandrayaan-1 spacecraft to identify specific signatures that definitively prove the water ice. The Moon Mineralogy Mapper not only picked up the reflective properties we’d expect from ice, but was able to directly measure the distinctive way its molecules absorb infrared light, so it can differentiate between liquid water or vapor and solid ice.

With enough ice sitting at the surface – within the top few millimeters – water would possibly be accessible as a resource for future expeditions to explore and even stay on the Moon, and potentially easier to access than the water detected beneath the Moon’s surface.

11. Bonus: Icy World Beyond Our Solar System!

With an estimated temperature of just 50K, OGLE-2005-BLG-390L b is the chilliest exoplanet yet discovered. Pictured here is an artist’s concept. Credit: NASA

OGLE-2005-BLG-390Lb, the icy exoplanet otherwise known as Hoth, orbits a star more than 20,000 light years away and close to the center of our Milky Way galaxy. It’s locked in the deepest of deep freezes, with a surface temperature estimated at minus 364 degrees Fahrenheit (minus 220 Celsius)!

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com.

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Standard Candles

So space is big. That’s a given. The thing is that I think people don’t really understand just how big it really is. We talk about exploring other galaxies and traveling to other solar systems like it’s just a couple clever innovations away, like it’s within our grasp if we just would try a little harder.

The thing is that everything is way, way, way farther away than for that to be the case. Even light takes multiple years to reach us from these “neighboring” celestial bodies.

So then, you might ask, how can we really know anything about those far away objects that are mere specks of light in galaxies far, far away?

Turns out a large part of that is standard candles. Standard candle is the term used to describe a celestial object with a known absolute luminosity (aka the strength of the source). If you know how strong the light is at a source, you can then measure the apparent luminosity from our little corner of the universe and use the inverse square law to determine how far away the source must be.

One class of objects commonly used for this purpose are Cephid variable stars. The thing is that stars can vary erratically in luminosity due to a whole bunch of things. Cephid variable stars, however, aren’t so unpredictable; instead their luminosity depends mostly on their mass, and the variation in luminosity that they do have is predictable and stable. Having a stable luminosity value for these stars is key, since this means we can extrapolate that data and determine how far away the star is from us here on Earth.

Anyway, that’s all for today. As always, stay spacey!

Sources: https://futurism.com/measuring-cosmic-distances

http://hubblesite.org/hubble_discoveries/dark_energy/de-type_ia_supernovae.php

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Celestial Fireworks - Official Hubble 25th Anniversary Image (2015).

Credit: NASA, ESA, The Hubble Heritage Team (STScI/AURA), A Nota, The Westerlund 2 Science Team

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Amid a backdrop of far-off galaxies, the majestic dusty spiral, NGC 3370, looms in the foreground in this NASA Hubble Space Telescope image. Recent observations taken with the Advanced Camera for Surveys show intricate spiral arm structure spotted with hot areas of new star formation. But this galaxy is more than just a pretty face. Nearly 10 years earlier NGC 3370, in the constellation Leo, hosted a bright exploding star.

In November 1994, the light of a supernova in nearby NGC 3370 reached Earth. This stellar outburst briefly outshone all of the tens of billions of other stars in its galaxy. Although supernovae are common, with one exploding every few seconds somewhere in the universe, this one was special. Designated SN 1994ae, this supernova was one of the nearest and best observed supernovae since the advent of modern, digital detectors. It resides 98 million light-years (30 megaparsecs) from Earth. The supernova was also a member of a special subclass of supernovae, the type Ia, the best tool astronomers have to chart the growth rate of the expanding universe.

Recently, astronomers have compared nearby type Ia supernovae to more distant ones, determining that the universe is now accelerating in its expansion and is filled with mysterious “dark energy.” Such measurements are akin to measuring the size of your room by stepping it off with your feet. However, a careful measurement of the length of your foot (to convert your measurements into inches or centimeters) is still needed to know the true size of your room. Similarly, astronomers must calibrate the true brightness of type Ia supernovae to measure the true size and expansion rate of the universe.

The very nearest type Ia supernovae, such as SN 1994ae, can be used to calibrate distance measurements in the universe, because other, fainter stars of known brightness can be observed in the same galaxy. These stellar “standard candles” are the Cepheid variable stars, which vary regularly in brightness with periods that are directly related to their intrinsic brightness, and thus allow the distance to the galaxy—and the supernova—to be determined directly. However, only the Hubble Space Telescope, equipped with its new Advanced Camera for Surveys, has the capability to resolve these individual Cepheids.

Adam Riess, an astronomer at Space Telescope Science Institute in Baltimore, Md., observed NGC 3370 a dozen times over the course of a month and has seen many Cepheid variables. Already he and his colleagues can see that these Cepheids are the most distant yet observed with Hubble. Because of their need to observe this galaxy with great frequency to record the variation of the Cepheids, the total exposure time for this galaxy is extremely long (about one full day), and the combined image provides one of the deepest views taken by Hubble. As a result, thousands of distant galaxies in the background are easily discernable.

Object Name: NGC 3370

Image Type: Astronomical

Credit: NASA, The Hubble Heritage Team and A. Riess (STScI)

Time And Space

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NGC 3621: Far Beyond the Local Group 

Image Credit & Copyright: Processing -Robert Gendler, Roberto Colombari Data - Hubble Legacy Archive, European Southern Observatory, et al.

Explanation: Far beyond the local group of galaxies lies NGC 3621, some 22 million light-years away…

Keep reading

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Introductions

I’ve been thinking a lot more about the universe lately, and in doing so I have found myself asking a lot of questions. How is the universe expanding? Why is it behaving the way it does? And perhaps most interestingly, how can we possibly know all of this from the vantage point of our tiny blue speck??

Well I intend to do my best to find out, and this blog is going to be a place for me to put some the answers I find. This also might be a place for me to just nerd out about space, so expect a steady stream of other space related content from other sources.

That’s all for introductions, stay spacey!

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“I know it’s just the simple shadow of our planet, but approaching the terminator gives me an eerie feeling every time. It’s as scary as it is fascinating,” writes European Space Agency (ESA) Astronaut Alexander Gerst on 16 September 2018. Planet Earth photographed from the ISS. [5568 x 3311] [OS]