juliensimon/nasa-apod huggingface dataset:
Apollo 17's Moonship (2019-12-19)

Awkward and angular looking, Apollo 17's lunar module Challenger was designed for flight in the near vacuum of space.  Digitally enhanced and reprocessed, this picture taken from Apollo 17's command module America shows Challenger's ascent stage in lunar orbit. Small reaction control thrusters are at the sides of the moonship with the bell of the ascent rocket engine underneath. The hatch allowing access to the lunar surface is seen at the front, with a round radar antenna at the top. Mission commander Gene Cernan is clearly visible through the triangular window. This spaceship performed gracefully, landing on the Moon and returning the Apollo astronauts to the orbiting command module in December of 1972. So where is Challenger now? Its descent stage remains at the Apollo 17 landing site in the Taurus-Littrow valley. The ascent stage pictured was intentionally crashed nearby after being jettisoned from the command module prior to the astronauts' return to planet Earth. Apollo 17's mission came to an end 47 years ago today. It was the sixth and last time astronauts landed on the Moon.
Late Afternoon on Mars (2019-12-20)

Shadows grow long near sunset in this wide panoramic view from the Curiosity rover on Mars. Made with Curiosity's navcam, the scene covers about 200 degrees from north through east to south (left to right), stitched together from frames taken by the Mars rover on sol 2616. That's just Earth date December 16. Curiosity is perched on top of a plateau on Western Butte. The distant northern rim of Gale crater is visible along the left. Near center is Central Butte, already visited by Curiosity. On the right, the shadow of the rover seems to stretch toward the base of Aeolis Mons (Mount Sharp), a future destination. The monochrome navcam frames have been colorized to approximate the colors of the late martian afternoon.
Solstice to Solstice Solargraph Timelapse (2019-12-21)

The 2019 December Solstice, on the first day of winter in planet Earth's northern hemisphere and summer in the south, is at 4:19 Universal Time December 22. That's December 21 for North America, though. Celebrate with a timelapse animation of the Sun's seasonal progression through the sky. It was made with solargraph images from an ingenious array of 27 pinhole cameras. The first frame from the Solarcan camera matrix was recorded near December 21, 2018. The last frame in the series finished near June 21, 2019, the northern summer solstice. All 27 camera exposures were started at the same time, with a camera covered and removed from the array once a week. Viewed consecutively the pinhole camera pictures accumulate the traces of the Sun's daily path from winter (bottom) to summer (top) solstice. Traces of the Sun's path are reflected by the foreground Williestruther Loch, in the Scottish Borders. Just select the image or follow this link to play the entire 27 frame (gif) timelapse.

Image credit: Sam Cornwell
Solstice Illuminated: A Year of Sky (2019-12-22)

Can you find which day is the winter solstice?  Each panel shows one day. With 360 movie panels, the sky over (almost) an entire year is shown in time lapse format as recorded by a video camera on the roof of the Exploratorium museum in San Francisco, California. The camera recorded an image every 10 seconds from before sunrise to after sunset and from mid-2009 to mid-2010.  A time stamp showing the local time of day is provided on the lower right. The videos are arranged chronologically, with July 28 shown on the upper left, and January 1 located about half way down.  In the videos, darkness indicates night, blue depicts clear day, while gray portrays pervasive daytime cloud cover. Many videos show complex patterns of clouds moving across the camera's wide field as that day progresses. The initial darkness in the middle depicts the delayed dawn and fewer daylight hours of winter. Although every day lasts 24 hours, nighttime lasts longest in the northern hemisphere in December and the surrounding winter months. Therefore, finding the panel with the longest night will locate the day of winter solstice -- which happens to be today in the northern hemisphere.  As the videos collectively end, sunset and then darkness descend first on the winter days just above the middle, and last on the mid-summer near the bottom.   Free Download: 2020 APOD Calendar

Image credit: Ken Murphy  
(MurphLab);
 Music:  Ariel (Moby)
Places for OSIRIS-REx to Touch Asteroid Bennu (2019-12-23)

Where is the best place to collect a surface sample from asteroid Bennu?  Launched in 2016, NASA sent the robotic Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer (OSIRIS-REx) to investigate the 500-meter-across asteroid 101955 Bennu. After mapping the near-Earth asteroid's dark surface, OSIRIS-REx will next touch Bennu's surface in 2020 August to collect a surface sample.  The featured 23-second time-lapse video shows four candidate locations for the touch, from which NASA chose just one earlier this month. NASA chose the Nightingale near Bennu's northern hemisphere as the primary touch-down spot because of its relative flatness, lack of boulders, and apparent abundance of fine-grained sand.  Location Osprey is the backup.  NASA plans to return soil samples from Bennu to Earth in 2023 for a detailed analysis.    Free Presentation: APOD Editor to show best astronomy images of 2019 -- and the decade -- in NYC on January 3
A Northern Winter Sky Panorama (2019-12-24)

What stars shine in Earth's northern hemisphere during winter? The featured image highlights a number of bright stars visible earlier this month. The image is a 360-degree horizontal-composite panorama of 66 vertical frames taken consecutively with the same camera and from the same location at about 2:30 am. Famous stars visible in the picture include Castor & Pollux toward the southeast on the left, Sirius just over the horizon toward the south, Capella just over the arch of the Milky Way Galaxy toward the west, and Polaris toward the north on the right.  Captured by coincidence is a meteor on the far left.  In the foreground is the Museum of the Orava Village in Zuberec, Slovakia. This village recreates rural life in the region hundreds of years ago, while the image captures a timeless sky surely familar to village residents, a sky also shared with northern residents around the world.    Free Download: 2020 APOD Calendar

Image credit: Tomas Slovinsky
An Annular Solar Eclipse over New Mexico (2019-12-25)

What is this person doing?  In 2012 an annular eclipse of the Sun was visible over a narrow path that crossed the northern Pacific Ocean and several western US states.  In an annular solar eclipse, the Moon is too far from the Earth to block out the entire Sun, leaving the Sun peeking out over the Moon's disk in a ring of fire.  To capture this unusual solar event, an industrious photographer drove from Arizona to New Mexico to find just the right vista. After setting up and just as the eclipsed Sun was setting over a ridge about 0.5 kilometers away, a person unknowingly walked right into the shot. Although grateful for the unexpected human element, the photographer never learned the identity of the silhouetted interloper. It appears likely, though, that the person is holding a circular device that would enable them to get their own view of the eclipse.  The shot was taken at sunset on 2012 May 20 at 7:36 pm local time from a park near Albuquerque, New Mexico, USA. Tomorrow another annular solar eclipse will become visible, this time along a thin path starting in Saudi Arabia and going through southern India, Singapore, and Guam.   However, almost all of Asia with a clear sky will be able to see, tomorrow, at the least, a partial solar eclipse.    Free Download: 2020 APOD Calendar

Image credit: Colleen Pinski
The Northern Winter Hexagon (2019-12-26)

December's New Moon brought a solar eclipse to some for the holiday season. It also gave beautiful dark night skies to skygazers around the globe, like this moonless northern winter night. In the scene, bright stars of the Winter Hexagon along the Milky Way are rising. Cosy mountain cabins in the snowy foreground are near the village of Oravska Lesna, Slovakia. The shining celestial beacons marking the well-known asterism are Aldebaran, Capella, Pollux (and Castor), Procyon, Rigel, and Sirius. This winter nightscape also reveals faint nebulae in Orion, and the lovely Pleiades star cluster. Slide your cursor over the image to trace the winter hexagon, or just follow this link.

Image credit: Petr
Horálek
A Partial Solar Eclipse Sequence Reflected (2019-12-27)

What's happened to the Sun?  Yesterday, if you were in the right place at the right time, you could see the Sun rise partially eclipsed by the Moon. The unusual sight was captured in dramatic fashion in the featured image not only directly, in a sequence of six images, but also in reflection from Soltan Salt Lake in Iran. The almost-white Sun appears dimmer and redder near the horizon primarily because Earth's atmosphere preferentially scatters away more blue light.  Yesterday's partial solar eclipse appeared in the sky over much of Asia and Australia, but those with a clear enough sky in a thin band across the Earth's surface were treated to a more complete annular solar eclipse -- where the Moon appears completely surrounded by the Sun in what is known as a ring of fire. The next annular solar eclipse will occur in 2020 June.   Notable Images Submitted to APOD: The Partial Solar Eclipse of 2019 December

Image credit: Majid Ghohroodi
A Distorted Sunrise Eclipse (2019-12-28)

Yes, but have you ever seen a sunrise like this?  Here, after initial cloudiness, the Sun appeared to rise in two pieces and during partial eclipse, causing the photographer to describe it as the most stunning sunrise of his life.  The dark circle near the top of the atmospherically-reddened Sun is the Moon -- but so is the dark peak just below it.  This is because along the way, the Earth's atmosphere had a layer of unusually warm air over the sea which acted like a gigantic lens and created a second image.  For a normal sunrise or sunset, this rare phenomenon of atmospheric optics is known as the Etruscan vase effect. The featured picture was captured two mornings ago from Al Wakrah, Qatar.  Some observers in a narrow band of Earth to the east were able to see a full annular solar eclipse -- where the Moon appears completely surrounded by the background Sun in a ring of fire.  The next solar eclipse, also an annular eclipse, will occur in 2020 June.    Notable Images Submitted to APOD: The Partial Solar Eclipse of 2019 December

Image credit: Elias Chasiotis
Cassini Spacecraft Crosses Saturn's Ring Plane (2019-12-29)

If this is Saturn, where are the rings?  When Saturn's "appendages" disappeared in 1612, Galileo did not understand why.   Later that century, it became understood that Saturn's unusual protrusions were rings and that when the Earth crosses the ring plane, the edge-on rings will appear to disappear.  This is because Saturn's rings are confined to a plane many times thinner, in proportion, than a razor blade.  In modern times, the robot Cassini spacecraft orbiting Saturn frequently crossed Saturn's ring plane during its mission to Saturn, from 2004 to 2017.  A series of plane crossing images from 2005 February was dug out of the vast online Cassini raw image archive by interested Spanish amateur Fernando Garcia Navarro.  Pictured here, digitally cropped and set in representative colors, is the striking result.  Saturn's thin ring plane appears in blue, bands and clouds in Saturn's upper atmosphere appear in gold. Details of Saturn's rings can be seen in the high dark shadows across the top of this image, taken back in 2005. The moons Dione and Enceladus appear as bumps in the rings.    Free Presentation: APOD Editor to show best astronomy images of 2019 -- and the decade -- in NYC on January 3
Messier 20 and 21 (2019-12-30)

The beautiful Trifid Nebula, also known as Messier 20, is easy to find with a small telescope in the nebula rich constellation Sagittarius. About 5,000 light-years away, the colorful study in cosmic contrasts shares this well-composed, nearly 1 degree wide field with open star cluster Messier 21 (top left). Trisected by dust lanes the Trifid itself is about 40 light-years across and a mere 300,000 years old. That makes it one of the youngest star forming regions in our sky, with newborn and embryonic stars embedded in its natal dust and gas clouds. Estimates of the distance to open star cluster M21 are similar to M20's, but though they share this gorgeous telescopic skyscape there is no apparent connection between the two. In fact, M21's stars are much older, about 8 million years old.

Image credit: Stanislav Volskiy
M33: The Triangulum Galaxy (2019-12-31)

The small, northern constellation Triangulum harbors this magnificent face-on spiral galaxy, M33. Its popular names include the Pinwheel Galaxy or just the Triangulum Galaxy. M33 is over 50,000 light-years in diameter, third largest in the Local Group of galaxies after the Andromeda Galaxy (M31), and our own Milky Way. About 3 million light-years from the Milky Way, M33 is itself thought to be a satellite of the Andromeda Galaxy and astronomers in these two galaxies would likely have spectacular views of each other's grand spiral star systems. As for the view from planet Earth, this sharp image shows off M33's blue star clusters and pinkish star forming regions along the galaxy's loosely wound spiral arms. In fact, the cavernous NGC 604 is the brightest star forming region, seen here at about the 7 o'clock position from the galaxy center. Like M31, M33's population of well-measured variable stars have helped make this nearby spiral a cosmic yardstick for establishing the distance scale of the Universe.

Image credit: Rui Liao
Betelgeuse Imagined (2020-01-01)

Why is Betelgeuse fading?  No one knows.  Betelgeuse, one of the brightest and most recognized stars in the night sky, is only half as bright as it used to be only five months ago.  Such variability is likely just  normal behavior for this famously variable supergiant, but the recent dimming has rekindled discussion on how long it may be before Betelgeuse does go supernova.  Known for its red color, Betelgeuse is one of the few stars to be resolved by modern telescopes, although only barely.  The featured artist's illustration imagines how Betelgeuse might look up close. Betelgeuse is thought to have a complex and tumultuous surface that frequently throws impressive flares.  Were it to replace the Sun (not recommended), its surface would extend out near the orbit of Jupiter, while gas plumes would bubble out past Neptune.  Since Betelgeuse is about 700 light years away, its eventual supernova will not endanger life on Earth even though its brightness may rival that of a full Moon.  Astronomers -- both amateur and professional -- will surely continue to monitor Betelgeuse as this new decade unfolds.    Free Presentation: APOD Editor to show best astronomy images of 2019 -- and the decade -- in NYC on January 3
The Fainting of Betelgeuse (2020-01-02)

Begirt with many a blazing star, Orion the Hunter is one of the most recognizable constellations. In this night skyscape the Hunter's stars rise in the northern hemisphere's winter sky on December 30, 2019, tangled in bare trees near Newnan, Georgia, USA. Red supergiant star Betelgeuse stands out in yellowish hues at Orion's shoulder left of center, but it no longer so strongly rivals the blue supergiant star Rigel at the Hunter's foot. In fact, skygazers around planet Earth can see a strikingly fainter Betelgeuse now, its brightness fading by more than half in the final months of 2019. Betelgeuse has long been known to be a variable star, changing its brightness in multiple cycles with approximate short and long term periods of hundreds of days to many years. The star is now close to its faintest since photometric measurements in 1926/27, likely due in part to a near coincidence in the minimum of short and long term cycles. Betelgeuse is also recognized as a nearby red supergiant star that will end its life in a core collapse supernova explosion sometime in the next 100,000 years, though that cosmic cataclysm will take place a safe 700 light-years or so from our fair planet.

Image credit: Jimmy Westlake
Quadrantids over the Great Wall (2020-01-03)

Named for a forgotten constellation, the Quadrantid Meteor Shower is an annual event for planet Earth's northern hemisphere skygazers The shower's radiant on the sky lies within the old, astronomically obsolete constellation Quadrans Muralis. That location is not far from the Big Dipper, at the boundaries of the modern constellations Bootes and Draco. With the radiant out of the frame at the upper right, Quadrantid meteors streak through this night skyscape composed of digital frames recorded in the hours around the shower's peak on January 4, 2013. The last quarter moon illuminates rugged terrain and a section of the Great Wall in Hebei Province, China. A likely source of the dust stream that produces Quadrantid meteors was identified in 2003 as an asteroid. As usual, in 2020 the shower is expected to peak briefly on the night of January 3/4. Meteor fans in North America can anticipate a good show to celebrate the new year in moonless skies before tomorrow's dawn.   Free Presentation: APOD Editor to show best astronomy images of 2019 -- and the decade -->tonight in NYC.

Image credit: Cheng Luo
Aurora Slathers Up the Sky (2020-01-04)

Like salsa verde on your favorite burrito, a green aurora slathers up the sky in this 2017 June 25 snapshot from the International Space Station. About 400 kilometers (250 miles) above Earth, the orbiting station is itself within the upper realm of the auroral displays. Aurorae have the signature colors of excited molecules and atoms at the low densities found at extreme altitudes. Emission from atomic oxygen dominates this view. The tantalizing glow is green at lower altitudes, but rarer reddish bands extend above the space station's horizon. The orbital scene was captured while passing over a point south and east of Australia, with stars above the horizon at the right belonging to the constellation Canis Major, Orion's big dog. Sirius, alpha star of Canis Major, is the brightest star near the Earth's limb.
A Starry Night of Iceland (2020-01-05)

On some nights, the sky is the best show in town. On this night, the sky was not only the best show in town, but a composite image of the sky won an international competition for landscape astrophotography. The featured winning image was taken in 2011 over J�kuls�rl�n, the largest glacial lake in Iceland.  The photographer combined six exposures to capture not only two green auroral rings, but their reflections off the serene lake. Visible in the distant background sky is the band of our Milky Way Galaxy and the Andromeda galaxy. A powerful coronal mass ejection from the Sun caused auroras to be seen as far south as Wisconsin, USA.  As the Sun progresses away from its current low in surface activity toward a solar maximum a few years away, many more spectacular images of aurora are expected.
Tumultuous Clouds of Jupiter (2020-01-06)

Some cloud patterns on Jupiter are quite complex. The featured tumultuous clouds were captured in May by NASA's robotic Juno spacecraft currently orbiting our Solar System's largest planet.  The image was taken when Juno was only about 15,000 kilometers over Jupiter's cloud tops, so close that less than half of the giant planet is visible.  The rough white clouds on the far right are high altitude clouds known as pop-up clouds.  Juno's mission, now extended into 2021, is to study Jupiter in new ways. Among many other things, Juno has been measuring Jupiter's gravitational field, finding surprising evidence that Jupiter may be mostly a liquid.
IC 405: The Flaming Star Nebula (2020-01-07)

Rippling dust and gas lanes give the Flaming Star Nebula its name.  The orange and purple colors of the nebula are present in different regions and are created by different processes.  The bright star AE Aurigae, visible toward the image left, is so hot it is blue, emitting light so energetic it knocks electrons away from surrounding gas.  When a proton recaptures an electron, red light is frequently emitted (depicted here in orange). The purple region's color is a mix of this red light and blue light emitted by AE Aurigae but reflected to us by surrounding dust. The two regions are referred to as emission nebula and reflection nebula, respectively.  Pictured here in the Hubble color palette, the Flaming Star Nebula, officially known as IC 405, lies about 1500 light years distant, spans about 5 light years, and is visible with a small telescope toward the constellation of the Charioteer (Auriga).

Image credit: Eric Coles
Galaxies in the River (2020-01-08)

Large galaxies grow by eating small ones. Even our own galaxy engages in a sort of galactic cannibalism, absorbing small galaxies that are too close and are captured by the Milky Way's gravity. In fact, the practice is common in the universe and illustrated by this striking pair of interacting galaxies from the banks of the southern constellation Eridanus, The River. Located over 50 million light years away, the large, distorted spiral NGC 1532 is seen locked in a gravitational struggle with dwarf galaxy NGC 1531 (right of center), a struggle the smaller galaxy will eventually lose. Seen edge-on, spiral NGC 1532 spans about 100,000 light-years. Nicely detailed in this sharp image, the NGC 1532/1531 pair is thought to be similar to the well-studied system of face-on spiral and small companion known as M51.

Image credit: Star Shadows Remote
Observatory
Perihelion to Aphelion (2020-01-09)

Perihelion for 2020, the point in Earth's elliptical orbit when it is closest to the Sun, occurred on January 5th. The distance from the Sun doesn't determine the seasons, though. Those are governed by the tilt of Earth's axis of rotation, so January is still winter in the north and summer in southern hemisphere. But it does mean that on January 5 the Sun was at its largest apparent size. This composite neatly compares two pictures of the Sun, both taken from planet Earth with the same telescope and camera. The left half was captured on the date of the 2020 perihelion. The right was recorded only a week before the July 4 date of the 2019 aphelion, the farthest point in Earth's orbit. Otherwise difficult to notice, the change in the Sun's apparent diameter between perihelion and aphelion amounts to a little over 3 percent. The 2020 perihelion and the preceding 2019 aphelion correspond to the closest and farthest perihelion and aphelion of the 21st century.

Image credit: Ian Griffin
Nacreous Clouds over Sweden (2020-01-10)

Vivid and lustrous, wafting iridescent waves of color filled this mountain and skyscape near Tanndalen, Sweden on January 3. Known as nacreous clouds or mother-of-pearl clouds, they are rare. This northern winter season they have been making unforgettable appearances at high latitudes, though. A type of polar stratospheric cloud, they form when unusually cold temperatures in the usually cloudless lower stratosphere form ice crystals. Still sunlit at altitudes of around 15 to 25 kilometers the clouds can diffract sunlight after sunset and before the dawn.

Image credit: Clear Skies