the-telescope-times

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HAPPY INTERNATIONAL CAT DAY

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2025 July 24

Titan Shadow Transit Image Credit & Copyright: Volodymyr Andrienko

Explanation: Every 15 years or so, Saturn’s rings are tilted edge-on to our line of sight. As the bright, beautiful ring system grows narrower and fainter it becomes increasingly difficult to see for denizens of planet Earth. But it does provide the opportunity to watch transits of Saturn’s moons and their dark shadows across the ringed gas giant’s still bright disk. Of course Saturn’s largest moon Titan is the easiest to spot in transit. In this telescopic snapshot from July 18, Titan itself is at the upper left, casting a round dark shadow on Saturn’s banded cloudtops above the narrow rings. In fact Titan’s transit season is in full swing now with shadow transits every 16 days corresponding to the moon’s orbital period. Its final shadow transit will be on October 6, though Titan’s pale disk will continue to cross in front of Saturn as seen from telescopes on planet Earth every 16 days through January 25, 2026.

∞ Source: apod.nasa.gov/apod/ap250724.html

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Downwind Dunes

The goal for this target is to look for and measure seasonal changes due to wind-driven processes since an earlier HiRISE observation. There are high flux dunes upwind, but how do they compare to the downwind dunes? The dunes in this image are called “barchan dunes”, whose shape indicates the direction of the wind. 

ID: ESP_076221_1380 date: 30 October 2022  altitude: 253 km

NASA/JPL-Caltech/University of Arizona

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A Sprite From Orbit

A sprite, also known as a red sprite, is an upper-atmospheric electrical discharge sometimes seen from thunderstorms. (Image credit: NASA; via P. Byrne) Read the full article

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2025 June 14

Meteors and Satellite Trails over the Limay River Image Credit & Copyright: Martín Moliné

Explanation: What are all those streaks in the sky? A galaxy, many satellite trails, and a few meteors. First, far in the distance, the majestic band of our Milky Way Galaxy runs down the left. Mirroring it on the right are several parallel trails of Earth-orbiting Starlink satellites. Many fainter satellite trails also crisscross the image. The two short and bright streaks are meteors — likely members of the annual Eta Aquariids meteor shower. The planet Venus shines on the lower right. Venus and the satellites shine by reflected sunlight. The featured picture is a composite of exposures all taken in a few hours on May 4 over the Limay River in Argentina.

∞ Source: apod.nasa.gov/apod/ap250614.html

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2025 June 16

APOD is 30 Years Old Today Image Credit: Pixelization of Van Gogh’s The Starry Night by Dario Giannobile

Explanation: APOD is 30 years old today. In celebration, today’s picture uses past APODs as tiles arranged to create a single pixelated image that might remind you of one of the most well-known and evocative depictions of planet Earth’s night sky. In fact, this Starry Night consists of 1,836 individual images contributed to APOD over the last 5 years in a mosaic of 32,232 tiles. Today, APOD would like to offer a sincere thank you to our contributors, volunteers, and readers. Over the last 30 years your continuing efforts have allowed us to enjoy, inspire, and share a discovery of the cosmos.

∞ Source: apod.nasa.gov/apod/ap250616.html

[the-telescope-times]

Cat's Eye Halo

The Cat’s Eye Nebula is a planetary nebula located in the Draco constellation. At its center is a dying star. (Image credit: T. Niittee; via APOD) Read the full article

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2025 June 1

UGC 1810: Wildly Interacting Galaxy from Hubble Image Credit: NASA, ESA, Hubble, HLA; Processing & Copyright: Domingo Pestana

Explanation: What’s happening to this spiral galaxy? Although details remain uncertain, it surely has to do with an ongoing battle with its smaller galactic neighbor. The featured galaxy is labelled UGC 1810 by itself, but together with its collisional partner is known as Arp 273. The overall shape of UGC 1810 – in particular its blue outer ring – is likely a result of wild and violent gravitational interactions. This ring’s blue color is caused by massive stars that are blue hot and have formed only in the past few million years. The inner galaxy appears older, redder, and threaded with cool filamentary dust. A few bright stars appear well in the foreground, unrelated to UGC 1810, while several galaxies are visible well in the background. Arp 273 lies about 300 million light years away toward the constellation of Andromeda. Quite likely, UGC 1810 will devour its galactic sidekick over the next billion years and settle into a classic spiral form.

∞ Source: apod.nasa.gov/apod/ap250601.html

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2025 June 2

Veil Nebula: Wisps of an Ancient Supernova Image Credit & Copyright: Abdullah Alharbi

Explanation: Wisps like this are all that remain visible of a Milky Way star. About 7,000 years ago that star exploded in a supernova, leaving the Veil Nebula. At the time, the expanding cloud was likely as bright as a crescent Moon, remaining visible for weeks to people living at the dawn of recorded history. Today, the resulting supernova remnant, also known as the Cygnus Loop, has faded and is now visible only through a small telescope directed toward the constellation of the Swan (Cygnus). The remaining Veil Nebula is physically huge, however, and even though it lies about 1,400 light-years distant, it covers over five times the size of the full Moon. The featured picture was taken in Kuwait in mid-2024 and features light emitted by hydrogen in red and oxygen in blue. In deep images of the complete Veil Nebula like this, even studious readers might not be able to identify the iconic filaments.

∞ Source: apod.nasa.gov/apod/ap250602.html

[the-telescope-times]

The Life of a Glacier on Mars

The life of glacier-like forms (GLFs) on Mars can be quite a drag, especially when having to push through all the Martian dust and rocks for millions of years. In this image, we see a potential debris-covered glacier spilling out onto relatively flat plains in Protonilus Mensae, spreading into a bulb-like lobe while bulldozing the surface in front of it.

After years of surface modification, different types of landforms develop. The most common glacial landforms on Mars are viscous flow features and curved, raised ridges at the terminus of a GLF called “moraines.”

This close-up image of the GLF surface also shows linear features resembling fractures, as seen on many terrestrial glaciers. Also visible on the sides of the valley walls are a��series of parallel lines that could potentially be exposed layers or lines that mark the GLF’s past levels.

Ice is one of the many powerful agents that can modify the surface of a planet. On Mars, water-ice tends to be more common in the mid- to high latitude regions and can serve as paleoclimate indicators or windows into the past climate of Mars.

ID: PSP_008809_2215 date: 12 June 2008 altitude: 297 km

NASA/JPL-Caltech/University of Arizona

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Interstellar Jets

This JWST image shows a couple of Herbig-Hero objects, seen in infrared. These bright objects form when jets of fast-moving energetic particles are expelled from the poles of a newborn star.  (Image credit: NASA/ESA/CSA/STScI/JWST; via APOD) Read the full article

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2025 May 20

Milky Way over Maunakea Image Credit & Copyright: Marzena Rogozinska

Explanation: Have you ever seen the band of our Milky Way Galaxy? In a clear sky from a dark location at the right time, a faint band of light becomes visible across the sky. Soon after your eyes become dark adapted, you might spot the band for the first time. It may then become obvious. Then spectacular. One reason for your growing astonishment might be the realization that this fuzzy swath, the Milky Way, contains billions of stars. Visible in the featured image, high above in the night sky, the band of the Milky Way Galaxy arcs. Also visible are the colorful clouds of Rho Ophiuchi on the right, and the red and circular Zeta Ophiuchi nebula near the top center. Taken in late February from Maunakea, Hawaii, USA, the foreground telescope is the University of Hawaii’s 2.2-Meter Telescope. Fortunately, you don’t need to be near the top of a Hawaiian volcano to see the Milky Way.

∞ Source: apod.nasa.gov/apod/ap250520.html

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Barchan and Linear Dunes

This image shows two types of sand dunes on Mars. The small dots are called barchan dunes, and from their shape we can tell that they are upwind. The downwind dunes are long and linear.

These two types of dunes each show the wind direction in different ways: the barchans have a steep slope and crescent-shaped “horns” that point downwind, while the linear dunes are stretched out along the primary wind direction. Linear dunes, however, typically indicate a wind regime with at least two different prevailing winds, which stretch out the sand along their average direction.

In several places in this image, you can find barchan dunes turning into linear dunes as they are stretched out, but they both seem into indicate the same wind direction. 

ID: ESP_062731_2645 date: 14 December 2019  altitude: 319 km

NASA/JPL-Caltech/University of Arizona

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2025 April 26

Barred Spiral Galaxy NGC 5335 Image Credit: NASA, ESA, STScI

Explanation: This stunning portrait of NGC 5335 was captured by the Hubble Space Telescope. Some 170,000 light-years across and over 200 million light-years away toward the constellation Virgo, the magnificent spiral galaxy is seen face-on in Hubble’s view. Within the galactic disk, loose streamers of star forming regions lie along the galaxy’s flocculent spiral arms. But the most striking feature of NGC 5335 is its prominent central bar. Seen in about 30 percent of galaxies, including our Milky Way, bar structures are understood to channel material inward toward the galactic center, fueling star formation. Of course, distant background galaxies are easy to spot, scattered around the sharp Hubble image. Launched in 1990, Hubble is now celebrating its 35th year exploring the cosmos from orbit around planet Earth.

∞ Source: apod.nasa.gov/apod/ap250426.html

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2025 April 27

IC 418: The Spirograph Nebula Image Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA); Acknowledgement: R. Sahai (JPL) et al.

Explanation: What is creating the strange texture of IC 418? Dubbed the Spirograph Nebula for its resemblance to drawings from a cyclical drawing tool, planetary nebula IC 418 shows patterns that are not well understood. Perhaps they are related to chaotic winds from the variable central star, which changes brightness unpredictably in just a few hours. By contrast, evidence indicates that only a few million years ago, IC 418 was probably a well-understood star similar to our Sun. Only a few thousand years ago, IC 418 was probably a common red giant star. Since running out of nuclear fuel, though, the outer envelope has begun expanding outward leaving a hot remnant core destined to become a white-dwarf star, visible in the image center. The light from the central core excites surrounding atoms in the nebula causing them to glow. IC 418 lies about 2000 light-years away and spans 0.3 light-years across. This false-color image taken from the Hubble Space Telescope reveals the unusual details.

∞ Source: apod.nasa.gov/apod/ap250427.html

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2025 April 29

Saturn’s Rings Appear to Disappear Image Credit & Copyright: Natan Fontes

Explanation: Where are Saturn’s ears? Galileo is credited, in 1610, as the first person to see Saturn’s rings. Testing out Lipperhey’s recently co-invented telescope, Galileo did not know what they were and so called them “ears”. The mystery deepened in 1612, when Saturn’s ears mysteriously disappeared. Today we know exactly what happened: from the perspective of the Earth, Saturn’s rings had become too thin to see. The same drama plays out every 15 years because Saturn, like Earth, undergoes tilt-driven seasons. This means that as Saturn goes around the Sun, its equator and rings can tilt noticeably toward the Sun and inner Solar System, making them easily visible, but from other orbital locations will appear almost not at all. The featured picture from Brasilia, Brazil shows a modern version of this sequence: the top ring-dominated image was taken in 2020, while the bottom ring-obscure image taken earlier in 2025.

∞ Source: apod.nasa.gov/apod/ap250429.html

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Curiously Curved Cliffs

This image shows a series of arcuate cliffs in the Tartarus Scopulus region of Mars. Here, the ground surface steps down toward the top of the image, and each step is about 5 to 10 meters tall.

The origin of these steps is not entirely understood, but they are likely the result of landslide-related processes, possibly down-hill creep of the ground surface above weak layers of rock or sediments underground.

ID: ESP_085829_1800 date: 17 November 2024 altitude: 272 km

NASA/JPL-Caltech/University of Arizona