juliensimon/nasa-apod huggingface dataset:
Solis Lacus: The Eye of Mars (2020-10-01)

As telescopes around planet Earth watch, Mars is growing brighter in night skies, approaching its 2020 opposition on October 13. Mars looks like it's watching too in this view of the Red Planet from September 22. Mars' disk is already near its maximum apparent size for earthbound telescopes, less than 1/80th the apparent diameter of a Full Moon. The seasonally shrinking south polar cap is at the bottom and hazy northern clouds are at the top. A circular, dark albedo feature, Solis Lacus (Lake of the Sun), is just below and left of disk center. Surrounded by a light area south of Valles Marineris, Solis Lacus looks like a planet-sized pupil, famously known as The Eye of Mars . Near the turn of the 20th century, astronomer and avid Mars watcher Percival Lowell associated the Eye of Mars with a conjunction of canals he charted in his drawings of the Red Planet. Broad, visible changes in the size and shape of the Eye of Mars are now understood from high resolution surface images to be due to dust transported by winds in the thin Martian atmosphere.

Image credit: Damian Peach
Biking to the Moon (2020-10-02)

As you watched October's first Full Moon rise last night, the Full Moon closest to the northern autumnal equinox, you were probably asking yourself, "How long would it take to bike to the Moon?" Sure, Apollo 11 astronauts made the trip in 1969, from launch to Moon landing, in about 103 hours or 4.3 days. But the Moon is 400,000 kilometers away. This year, the top bike riders in planet Earth's well-known Tour de France race covered almost 3,500 kilometers in 21 stages after about 87 hours on the road. That gives an average speed of about 40 kilometers per hour and a lunar cycling travel time of 10,000 hours, a little over 416 days. While this bike rider's destination isn't clear, his journey did begin around moonrise on September 27 near Cleeve Hill, Bishops Cleeve, Cheltenham, UK.

Image credit: Susan Snow
Driving to the Sun (2020-10-03)

How long would it take to drive to the Sun? Brittany age 7, and D.J. age 12, ponder this question over dinner one evening. James also age 7, suggests taking a really fast racing car while Christopher age 4, eagerly agrees. Jerry, a really old guy who is used to estimating driving time on family trips based on distance divided by speed, offers to do the numbers. "Let's see ... the Sun is 93 million miles away. If we drove 93 miles per hour the trip would only take us 1 million hours." How long is 1 million hours? One year is 365 days times 24 hours per day, or 8,760 hours. One hundred years would be 876,000 hours, but that's still a little short of the 1 million hour drive time. So the Sun is really quite far away. Christopher is not impressed, but as he grows older he will be. You've got to be impressed by something that's 93 million miles away and still hurts your eyes when you look at it!
Orion Nebula in Oxygen, Hydrogen, and Sulfur (2020-10-04)

Few astronomical sights excite the imagination like the nearby stellar nursery known as the Orion Nebula.  The Nebula's glowing gas surrounds hot young stars at the edge of an immense interstellar molecular cloud.  Many of the filamentary structures visible in the featured image are actually shock waves - fronts where fast moving material encounters slow moving gas.  The Orion Nebula spans about 40 light years and is located about 1500 light years away in the same spiral arm of our Galaxy as the Sun.  The Great Nebula in Orion can be found with the unaided eye just below and to the left of the easily identifiable belt of three stars in the popular constellation Orion.  The image shows the nebula in three colors specifically emitted by hydrogen, oxygen, and sulfur gas.  The whole Orion Nebula cloud complex, which includes the Horsehead Nebula, will slowly disperse over the next 100,000 years.

Image credit: César Blanco González
NGC 5643: Nearby Spiral Galaxy from Hubble (2020-10-05)

What's happening at the center of spiral galaxy NGC 5643?  A swirling disk of stars and gas, NGC 5643's appearance is dominated by blue spiral arms and brown  dust, as shown in the featured image taken by the Hubble Space Telescope.   The core of this active galaxy glows brightly in radio waves and X-rays where twin jets have been found.  An unusual central glow makes NGC 5643 one of the closest examples of the Seyfert class of galaxies, where vast amounts of glowing gas are thought to be falling into a central massive black hole.  NGC 5643, is a relatively close 55 million light years away, spans about 100 thousand light years across, and can be seen with a small telescope towards the constellation of the Wolf (Lupus).
Mars Approach 2020 (2020-10-06)

Look to the east just after sunset tonight and you'll see a most impressive Mars. Tonight, Mars will appear its biggest and brightest of the year, as Earth passes closer to the red planet than it has in over two years -- and will be again for another two years.  In a week, Mars will be almost as bright -- but at opposition, meaning that it will be directly opposite the Sun. Due to the slightly oval shape of the orbits of Mars and Earth, closest approach and opposition occur on slightly different days. The featured image sequence shows how the angular size of Mars has grown during its approach over the past few months. Noticeably orange, Mars is now visible nearly all night long, reflecting more sunlight toward Earth than either Saturn or Jupiter.  Even at its closest and largest, though, Mars will still appear about 100 times smaller, in diameter, than a full moon.
Ou4: A Giant Squid in a Flying Bat (2020-10-07)

A very faint but very large squid-like nebula is visible in planet Earth's sky -- but inside a still larger bat.  The Giant Squid Nebula cataloged as Ou4, and Sh2-129 also known as the Flying Bat Nebula, are both caught in this cosmic scene toward the royal royal constellation Cepheus. Composed with 55 hours of narrowband image data, the telescopic field of view is 3 degrees or 6 Full Moons across. Discovered in 2011 by French astro-imager Nicolas Outters, the Squid Nebula's alluring bipolar shape is distinguished here by the telltale blue-green emission from doubly ionized oxygen atoms. Though apparently completely surrounded by the reddish hydrogen emission region Sh2-129, the true distance and nature of the Squid Nebula have been difficult to determine. Still, a more recent investigation suggests Ou4 really does lie within Sh2-129 some 2,300 light-years away. Consistent with that scenario, Ou4 would represent a spectacular outflow driven by HR8119, a triple system of hot, massive stars seen near the center of the nebula. The truly giant Squid Nebula would physically be nearly 50 light-years across.   New: APOD Mirror in Turkish from Rasyonalist

Image credit: Yannick Akar
Mare Frigoris (2020-10-08)

Lighter than typically dark, smooth, mare the Mare Frigoris lies in the far lunar north. Also known as the Sea of Cold, it stretches across the familiar lunar nearside in this close up of the waxing gibbous Moon's north polar region. Dark-floored, 95 kilometer wide crater Plato is just left of the center. Sunlit peaks of the lunar Alps (Montes Alpes) are highlighted below and right of Plato, between the more southern Mare Imbrium (Sea of Rains) and Mare Frigoris. The prominent straight feature cutting through the mountains is the lunar Alpine Valley (Vallis Alpes). Joining the Mare Imbrium and Mare Frigoris, the lunar valley is about 160 kilometers long and up to 10 kilometers wide.

Image credit: Matt Smith
The Very Large Array at Moonset (2020-10-09)

An inspirational sight, these giant dish antennas of the Karl G. Jansky Very Large Array (VLA) rise above the New Mexico desert at moonset.  Mounted on piers but transportable on railroad tracks to change the VLA’s configuration, its 27 operating antennas are each house-sized (25 meters across) and can be organized into an array spanning the size of a city (35 kilometers). A prolific radio astronomy workhorse, the VLA has been used to discover water on planet Mercury, radio-bright coronae around stars, micro-quasars in our Galaxy, gravitationally-induced Einstein rings around distant galaxies, and radio counterparts to cosmologically distant gamma-ray bursts. Its vast size has allowed astronomers to study the details of radio galaxies, super-fast cosmic jets, and map the center of our own Milky Way. Now 40 years since its dedication the VLA has been used in more than 14,000 observing projects and contributed to more than 500 Ph.D. dissertations. On October 10, the National Radio Astronomy Observatory will host a day-long online celebration of the VLA at 40 featuring virtual tours and presentations on the history, operations, science, and future of the Very Large Array.
Virgo Cluster Galaxies (2020-10-10)

Galaxies of the Virgo Cluster are scattered across this deep telescopic field of view. The cosmic scene spans about three Full Moons, captured in dark skies near Jalisco, Mexico, planet Earth. About 50 million light-years distant, the Virgo Cluster is the closest large galaxy cluster to our own local galaxy group. Prominent here are Virgo's bright elliptical galaxies from the Messier catalog, M87 at the top left, and M84 and M86 seen (bottom to top) below and right of center. M84 and M86 are recognized as part of Markarian's Chain, a visually striking line-up of galaxies vertically on the right side of this frame. Near the middle of the chain lies an intriguing interacting pair of galaxies, NGC 4438 and NGC 4435, known to some as Markarian's Eyes. Of course giant elliptical galaxy M87 dominates the Virgo cluster. It's the home of a super massive black hole, the first black hole ever imaged by planet Earth's Event Horizon Telescope.

Image credit: Fernando Pena
Milky Way over the Pinnacles in Australia (2020-10-11)

What strange world is this? Earth. In the foreground of the featured image are the Pinnacles, unusual rock spires in Nambung National Park in Western Australia. Made of ancient sea shells (limestone), how these human-sized picturesque spires formed remains unknown.  In the background, just past the end of the central Pinnacle, is a bright crescent Moon. The eerie glow around the Moon is mostly zodiacal light, sunlight reflected by dust grains orbiting between the planets in the Solar System. Arching across the top is the central band of our Milky Way Galaxy. Many famous stars and nebulas are also visible in the background night sky. The featured 29-panel panorama was taken and composed in 2015 September after detailed planning that involved the Moon, the rock spires, and their corresponding shadows. Even so, the strong zodiacal light was a pleasant surprise.

Image credit: Michael Goh
Descending Toward Asteroid Bennu (2020-10-12)

What would it be like to land on an asteroid?  Although no human has yet done it, NASA's robotic OSIRIS-REx spacecraft is scheduled to attempt to touch the surface of asteroid 101955 Bennu next week.  The goal is to collect a sample from the nearby minor planet for return to Earth for a detailed analysis in 2023. The featured video shows what it looks like to descend toward the 500-meter diamond-shaped asteroid, based on a digital map of Bennu's rocky surface constructed from image and surface data taken by OSIRIS-REx over the past 1.5 years.  The video begins by showing a rapidly spinning Bennu -- much faster than its real rotation period of 4.3 hours.  After the rotation stops, the virtual camera drops you down to just above the rugged surface and circles a house-sized rock outcrop named Simurgh, with the flatter outcrop Roc visible behind it.  If the return sample reaches Earth successfully, it will be scrutinized for organic compounds that might have seeded a young Earth, rare or unusual elements and minerals, and clues about the early history of our Solar System.
Mars, Pleiades, and Andromeda over Stone Lions (2020-10-13)

Three very different -- and very famous -- objects were all captured in a single frame last month. On the upper left is the bright blue Pleiades, perhaps the most famous cluster of stars on the night sky.  The Pleiades (M45) is about 450 light years away and easily found a few degrees from Orion.  On the upper right is the expansive Andromeda Galaxy, perhaps the most famous galaxy -- external to our own -- on the night sky.  Andromeda (M31) is one of few objects visible to the unaided eye where you can see light that is millions of years old.  In the middle is bright red Mars, perhaps the most famous planet on the night sky. Today Mars is at opposition, meaning that it is opposite the Sun, with the result that it is visible all night long.  In the foreground is an ancient tomb in the Phygrian Valley in Turkey.  The tomb, featuring two stone lions, is an impressive remnant of a powerful civilization that lived thousands of years ago.  Mars, currently near its brightest, can be easily found toward the east just after sunset.

Image credit: Cem Özkeser
The Colorful Clouds of Rho Ophiuchi (2020-10-14)

The many spectacular colors of the Rho Ophiuchi (oh'-fee-yu-kee) clouds highlight the many processes that occur there.  The blue regions shine primarily by reflected light.  Blue light from the  Rho Ophiuchi star system and nearby stars reflects more efficiently off this portion of the nebula than red light.  The Earth's daytime sky appears blue for the same reason.  The red and yellow regions shine primarily because of emission from the nebula's atomic and molecular gas.  Light from nearby blue stars - more energetic than the bright star  Antares - knocks electrons away from the gas, which then shines when the electrons recombine with the gas.  The dark brown regions are caused by dust grains - born in young stellar atmospheres - which effectively block light emitted behind them.  The Rho Ophiuchi star clouds, well in front of the globular cluster M4 visible here on the upper right, are even more colorful than humans can see - the clouds emits light in every wavelength band from the radio to the gamma-ray.   Astrophysicists: Browse 2,200+ codes in the Astrophysics Source Code Library

Image credit: Amir H. Abolfath
Galaxies in Pegasus (2020-10-15)

This sharp telescopic view reveals galaxies scattered beyond the stars of the Milky Way, at the northern boundary of the high-flying constellation Pegasus. Prominent at the upper right is NGC 7331. A mere 50 million light-years away, the large spiral is one of the brighter galaxies not included in Charles Messier's famous 18th century catalog. The disturbed looking group of galaxies at the lower left is well-known as Stephan's Quintet. About 300 million light-years distant, the quintet dramatically illustrates a multiple galaxy collision, its powerful, ongoing interactions posed for a brief cosmic snapshot. On the sky, the quintet and NGC 7331 are separated by about half a degree.

Image credit: Robert Eder
Planetary Nebula Abell 78 (2020-10-16)

Planetary nebula Abell 78 stands out in this colorful telescopic skyscape. In fact the colors of the spiky Milky Way stars depend on their surface temperatures, both cooler (yellowish) and hotter (bluish) than the Sun. But Abell 78 shines by the characteristic emission of ionized atoms in the tenuous shroud of material shrugged off from an intensely hot central star. The atoms are ionized, their electrons stripped away, by the central star's energetic but otherwise invisible ultraviolet light. The visible blue-green glow of loops and filaments in the nebula's central region corresponds to emission from doubly ionized oxygen atoms, surrounded by strong red emission from electrons recombining with hydrogen atoms. Some 5,000 light-years distant toward the constellation Cygnus, Abell 78 is about three light-years across. A planetary nebula like Abell 78 represents a very brief final phase in stellar evolution that our own Sun will experience ... in about 5 billion years.

Image credit: Bernhard Hubl
Cygnus: Bubble and Crescent (2020-10-17)

These clouds of gas and dust drift through rich star fields along the plane of our Milky Way Galaxy toward the high flying constellation Cygnus. Caught within the telescopic field of view are the Soap Bubble (lower left) and the Crescent Nebula (upper right). Both were formed at a final phase in the life of a star. Also known as NGC 6888, the Crescent was shaped as its bright, central massive Wolf-Rayet star, WR 136, shed its outer envelope in a strong stellar wind. Burning through fuel at a prodigious rate, WR 136 is near the end of a short life that should finish in a spectacular supernova explosion.  Discovered in 2013, the Soap Bubble Nebula is likely a planetary nebula, the final shroud of a lower mass, long-lived, sun-like star destined to become a slowly cooling white dwarf. Both stellar shrouds are 5,000 light-years or so distant. The larger Crescent Nebula is around 25 light-years across.

Image credit: Wissam Ayoub
UGC 1810: Wildly Interacting Galaxy from Hubble (2020-10-18)

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.    APOD in world languages: Arabic, Catalan, Chinese (Beijing), Chinese (Taiwan), Croatian, Czech, Dutch, Farsi, French, German, Hebrew, Indonesian, Japanese, Korean, Montenegrin, Polish, Russian, Serbian, Slovenian,  Spanish, Turkish, Turkish, and  Ukrainian

Image credit: Domingo Pestana
A Flight over Jupiter Near the Great Red Spot (2020-10-19)

Are you willing to wait to see the largest and oldest known storm system in the Solar System?  In the featured video, Jupiter's Great Red Spot finally makes its appearance 2 minutes and 12 seconds into the 5-minute video.  Before it arrives, you may find it pleasing to enjoy the continually changing view of the seemingly serene clouds of Jupiter, possibly with your lights low and sound up.  The 41 frames that compose the video were captured in June as the robotic Juno spacecraft was making a close pass over our Solar System's largest planet. The time-lapse sequence actually occurred over four hours.  Since arriving at Jupiter in 2016, Juno's numerous discoveries have included unexpectedly deep atmospheric jet streams, the most powerful auroras ever recorded, and water-bearing clouds bunched near Jupiter's equator.   Follow: Live coverage of tomorrow's OSIRIS-REx attempted touchdown-and-go on asteroid Bennu
Saturn and Jupiter over Italian Peaks (2020-10-20)

Saturn and Jupiter are getting closer. Every night that you go out and check for the next two months, these two bright planets will be even closer together on the sky.  Finally, in mid-December, a Great Conjunction will occur -- when the two planets will appear only 0.1 degrees apart -- just one fifth the angular diameter of the full Moon. And this isn't just any Great Conjunction -- Saturn (left) and Jupiter (right) haven't been this close since 1623, and won't be nearly this close again until 2080.  This celestial event is quite easy to see -- already the two planets are easily visible toward the southwest just after sunset -- and already they are remarkably close. Pictured, the astrophotographer and partner eyed the planetary duo above the Tre Cime di Lavaredo (Three Peaks of Lavaredo) in the Italian Alps about two weeks ago.    Follow: Live coverage of today's OSIRIS-REx attempted touchdown-and-go on asteroid Bennu

Image credit: Giorgia Hofer
A Night Sky Vista from Sardinia (2020-10-21)

How many famous sky objects can you find in this image?  The featured dark sky composite combines over 60 exposures spanning over 220 degrees to create a veritable menagerie of night sky wonders. Visible celestial icons include the Belt of Orion, the Orion Nebula, the Andromeda Galaxy, the California Nebula, and bright stars Sirius and Betelgeuse.  You can verify that you found these, if you did, by checking an annotated version of the image.  A bit harder, though, is finding Polaris and the Big Dipper. Also discernible are several meteors from the Quandrantids meteor shower, red and green airglow, and two friends of the astrophotographer.  The picture was captured in January from Sardinia, Italy.  You can see sky wonders in your own night sky tonight -- including more meteors than usual -- because tonight is near peak of the yearly Orionids meteor shower.   News: NASA’s OSIRIS-REx Spacecraft Successfully Touches Asteroid

Image credit: Tomáš Slovinský
Tagging Bennu (2020-10-22)

On October 20, after a careful approach to the boulder-strewn surface, the OSIRIS-REx spacecraft's arm reached out and touched asteroid Bennu. Dubbed a Touch-And-Go (TAG) sampling event, the 30 centimeter wide sampling head (TAGSAM) appears to crush some of the rocks in this snapshot. The close-up scene was recorded by the spacecraft's SamCam some 321 million kilometers from planet Earth, just after surface contact. One second later, the spacecraft fired nitrogen gas from a bottle intended to blow a substantial amount of Bennu's regolith into the sampling head, collecting the loose surface material. Data show the spacecraft spent approximately 5 more seconds in contact with Bennu's Nightingale sample site and then performed its back-away burn. Timelapse frames from SamCam reveal the aftermath.
Supernova in NGC 2525 (2020-10-23)

Big, beautiful, barred spiral galaxy NGC 2525 lies 70 million light-years from the Milky Way. It shines in Earth's night sky within the boundaries of the southern constellation Puppis. About 60,000 light-years across, its spiral arms lined with dark dust clouds, massive blue stars, and pinkish starforming regions wind through this gorgeous Hubble Space Telescope snapshot. Spotted on the outskirts of NGC 2525 in January 2018, supernova SN 2018gv is the brightest star in the frame at the lower left. In time-lapse, a year long series of Hubble observations followed the stellar explosion, the nuclear detonation of a white dwarf star triggered by accreting material from a companion star, as it slowly faded from view. Identified as a Type Ia supernova, its brightness is considered a cosmic standard candle. Type Ia supernovae are used to measure distances to galaxies and determine the expansion rate of the Universe.
Globular Star Cluster 47 Tuc (2020-10-24)

Globular star cluster 47 Tucanae is a jewel of the southern sky. Also known as NGC 104, it roams the halo of our Milky Way Galaxy along with some 200 other globular star clusters. The second brightest globular cluster (after Omega Centauri) as seen from planet Earth, it lies about 13,000 light-years away and can be spotted naked-eye close on the sky to the Small Magellanic Cloud in the constellation of the Toucan. The dense cluster is made up of hundreds of thousands of stars in a volume only about 120 light-years across. Red giant stars on the outskirts of the cluster are easy to pick out as yellowish stars in this sharp telescopic portrait. Tightly packed globular cluster 47 Tuc is also home to a star with the closest known orbit around a black hole.

Image credit: Jose Mtanous