juliensimon/nasa-apod huggingface dataset:
Extraordinary Solar Halos (2018-12-21)

Welcome to the December Solstice, the first day of winter in planet Earth's northern hemisphere and summer in the south. To celebrate, consider this extraordinary display of beautiful solar ice halos! More common than rainbows, simple ice halos can be easy to spot, especially if you can shade your eyes from direct sunlight. Still it's extremely rare to see anything close to the complex of halos present in this astounding scene. Captured at lunchtime on a cold December 14 near Utendal, Sweden the image includes the relatively ordinary 22 degree halo, sundogs (parhelia) and sun pillars. The extensive array of rarer halos has been identified along with previously unknown features. All the patterns are generated as sunlight (or moonlight) is reflected and refracted in flat six-sided water ice crystals in Earth's atmosphere. In this case, likely local contributors to the atmospheric ice crystals are snow making machines operating at a nearby ski center.

Image credit: Magnus Edback
A Cold December Night (2018-12-22)

They say Orion always comes up sideways, and he does seem to on this cold December night. The bright stars of the familiar northern winter constellation lie just above the snowy tree tops surrounding a cozy cottage near the town of Ustupky in the Czech Republic. But Gemini's meteors also seem to rain on the wintry landscape. The meteor streaks are captured in exposures made near last Friday's peak of the annual Geminid meteor shower. They stream away from the shower's radiant above the trees, near the two bright stars of the zodiacal constellation of the Twins. Comet Wirtanen, a visitor to planet Earth's skies, is visible too. Look for its telltale greenish coma near the stars of the seven sisters.

Image credit: Petr Horálek
Earthrise: A Video Reconstruction (2018-12-23)

About 12 seconds into this video, something unusual happens. The Earth begins to rise.  Never seen by humans before, the rise of the Earth over the limb of the Moon occurred 50 years ago tomorrow and surprised and amazed the crew of Apollo 8. The crew immediately scrambled to take still images of the stunning vista caused by Apollo 8's orbit around the Moon. The featured video is a modern reconstruction of the event as it would have looked were it recorded with a modern movie camera. The colorful orb of our Earth stood out as a familiar icon rising above a distant and unfamiliar moonscape, the whole scene the conceptual reverse of a more familiar moonrise as seen from Earth. To many, the scene also spoke about the unity of humanity: that big blue marble -- that's us -- we all live there. The two-minute video is not time-lapse -- this is the real speed of the Earth rising through the windows of Apollo 8. Seven months and three missions later, Apollo 11 astronauts would not only circle Earth's moon, but land on it.
Earthrise 1: Historic Image Remastered (2018-12-24)

"Oh my God! Look at that picture over there! Here's the Earth coming up. Wow is that pretty!" Soon after that pronouncement, 50 years ago today, one of the most famous images ever taken was snapped from the orbit of the Moon. Now known as "Earthrise", the iconic image shows the Earth rising above the limb of the Moon, as taken by the crew of Apollo 8.  But the well-known Earthrise image was actually the  second image taken of the Earth rising above the lunar limb -- it was just the first in color.  With modern digital technology, however, the real first Earthrise image -- originally in black and white -- has now been remastered to have the combined resolution and color of the first three images.  Behold! The featured image is a close-up of the picture that Apollo 8 astronaut Bill Anders was talking about. Thanks to modern technology and human ingenuity, now we can all see it. (Historical note: A different historic black & white image of the Earth setting behind the lunar limb was taken by the robotic Lunar Orbiter 1 two years earlier.)
M100: A Grand Design Spiral Galaxy (2018-12-25)

Majestic on a truly cosmic scale, M100 is appropriately known as a grand design spiral galaxy.  It is a large galaxy of over 100 billion stars with well-defined spiral arms that is similar to our own Milky Way Galaxy.  One of the brightest members of the Virgo Cluster of galaxies, M100 (alias NGC 4321) is 56 million light-years distant toward the constellation of Berenice's Hair (Coma Berenices).  This Hubble Space Telescope image of M100 was taken recently with the Wide Field Camera 3 and accentuates bright blue star clusters and intricate winding dust lanes which are hallmarks of this class of galaxies.  Studies of variable stars in M100 have played an important role in determining the size and age of the Universe.
NGC 6357: The Lobster Nebula (2018-12-26)

Why is the Lobster Nebula forming some of the most massive stars known? No one is yet sure.  Cataloged as NGC 6357, the Lobster Nebula houses the open star cluster Pismis 24 near its center -- a home to unusually bright and massive stars.  The overall blue glow near the inner star forming region results from the emission of ionized hydrogen gas.   The surrounding nebula, featured here, holds a complex tapestry of gas, dark dust, stars still forming, and newly born stars.  The intricate patterns are caused by complex interactions between interstellar winds, radiation pressures, magnetic fields, and gravity.  NGC 6357 spans about 400 light years and lies about 8,000 light years away toward the constellation of the Scorpion.   Free Download: 2019 APOD Calendar (v5)
The Great Carina Nebula (2018-12-27)

A jewel of the southern sky, the Great Carina Nebula, also known as NGC 3372, spans over 300 light-years, one of our galaxy's largest star forming regions. Like the smaller, more northerly Great Orion Nebula, the Carina Nebula is easily visible to the unaided eye, though at a distance of 7,500 light-years it is some 5 times farther away. This gorgeous telescopic close-up reveals remarkable details of the region's central glowing filaments of interstellar gas and obscuring cosmic dust clouds. The field of view is over 50 light-years across. The Carina Nebula is home to young, extremely massive stars, including the stars of open cluster Trumpler 14 (above and left of center) and the still enigmatic variable Eta Carinae, a star with well over 100 times the mass of the Sun.  Eta Carinae is the brightest star, centered here just below the dusty Keyhole Nebula (NGC 3324). While Eta Carinae itself maybe on the verge of a supernova explosion, X-ray images indicate that the Great Carina Nebula has been a veritable supernova factory.

Image credit: Maicon Germiniani
NGC 1365: Majestic Island Universe (2018-12-28)

Barred spiral galaxy NGC 1365 is truly a majestic island universe some 200,000 light-years across. Located a mere 60 million light-years away toward the chemical constellation Fornax, NGC 1365 is a dominant member of the well-studied Fornax galaxy cluster. This impressively sharp color image shows intense star forming regions at the ends of the bar and along the spiral arms, and details of dust lanes cutting across the galaxy's bright core. At the core lies a supermassive black hole. Astronomers think NGC 1365's prominent bar plays a crucial role in the galaxy's evolution, drawing gas and dust into a star-forming maelstrom and ultimately feeding material into the central black hole.

Image credit: island universe
New Horizons at Ultima Thule (2018-12-29)

When we celebrate the start of 2019, on January 1 the New Horizons spacecraft will fly by Ultima Thule. A world of the Kuiper belt 6.5 billion kilometers from the Sun, the nickname Ultima Thule (catalog designation 2014 MU69) fittingly means "beyond the known world". Following its 2015 flyby of Pluto, New Horizons was targeted for this journey, attempting the most distant flyby for a spacecraft from Earth by approaching Ultima Thule to within about 3500 kilometers. The tiny world itself is about 30 kilometers in size. In 2017 and 2018, observing campaigns with Earth-based telescopes determined the shape of the object to be a contact binary or a close binary sytem as in this artist's illustration. New Horizons will image close up its unexplored surface in the dim light of the distant Sun.
The Galaxy Tree (2018-12-30)

First came the trees. In the town of Salamanca, Spain, the photographer noticed how distinctive a grove of oak trees looked after being pruned.  Next came the galaxy. The photographer stayed up until 2 am, waiting until the Milky Way Galaxy rose above the level of a majestic looking oak.  From this carefully chosen perspective, dust lanes in the galaxy appear to be natural continuations to branches of the tree.  Last came the light. A flashlight was used on the far side of the tree to project a silhouette. By coincidence, other trees also appeared as similar silhouettes across the relatively bright horizon. The featured image was captured as a single 30-second frame in 2015 and processed to digitally enhance the Milky Way.   Free Download: 2019 APOD Calendar (v5)

Image credit: C�sar Vega Toledano ; 
 Rollover Annotation:  Judy Schmidt
The Witch Head Nebula (2018-12-31)

Double, double toil and trouble; Fire burn, and cauldron bubble .... maybe Macbeth should have consulted the Witch Head Nebula. A frighteningly shaped reflection nebula, this cosmic crone is about 800 light-years away though. Its malevolent visage seems to glare toward nearby bright star Rigel in Orion, just off the left edge of this frame. More formally known as IC 2118, the interstellar cloud of dust and gas is nearly 70 light-years across, its dust grains reflecting Rigel's starlight. In this composite portrait, the nebula's color is caused not only by the star's intense bluish light but because the dust grains scatter blue light more efficiently than red. The same physical process causes Earth's daytime sky to appear blue, although the scatterers in planet Earth's atmosphere are molecules of nitrogen and oxygen.   Free Download: 2019 APOD Calendar (v5)

Image credit: Digitized Sky Survey (POSS II); 
 Processing: 
Utkarsh Mishra
The Sombrero Galaxy in Infrared (2019-01-01)

This floating ring is the size of a galaxy.  In fact, it is a galaxy -- or at least part of one: the photogenic Sombrero Galaxy, one of the largest galaxies in the nearby Virgo Cluster of Galaxies.  The dark band of dust that obscures the mid-section of the Sombrero Galaxy in optical light actually glows brightly in infrared light.  The featured image, digitally sharpened, shows the infrared glow, recently recorded by the orbiting Spitzer Space Telescope, superposed in false-color on an existing image taken by NASA's Hubble Space Telescope in optical light. The Sombrero Galaxy, also known as M104, spans about 50,000 light years across and lies 28 million light years away.  M104 can be seen with a small telescope in the direction of the constellation Virgo.   News: New Horizons Spacecraft Passes Ultima Thule
The Orion Nebula in Infrared from WISE (2019-01-02)

The Great Nebula in Orion is an intriguing place.  Visible to the unaided eye, it appears as a small fuzzy patch in the constellation of Orion. But this image, an illusory-color four-panel mosaic taken in different bands of infrared light with the Earth orbiting WISE observatory, shows the Orion Nebula to be a bustling  neighborhood of recently formed stars, hot gas, and dark dust.  The power behind much of the Orion Nebula (M42) is the stars of the Trapezium star cluster, seen near the center of the featured image. The orange glow surrounding the bright stars pictured here is their own starlight reflected by intricate dust filaments that cover much of the region.  The current  Orion Nebula cloud complex, which includes the Horsehead Nebula, will slowly disperse over the next 100,000 years.   News: New Horizons Results from Ultima Thule

Image credit: :
Francesco Antonucci
Ultima and Thule (2019-01-03)

On January 1 New Horizons encountered the Kuiper Belt object nicknamed Ultima Thule. Some 6.5 billion kilometers from the Sun, Ultima Thule is the most distant world ever explored by a spacecraft from Earth. This historic image, the highest resolution image released so far, was made at a range of about 28,000 kilometers only 30 minutes before the New Horizons closest approach. Likely the result of a gentle collision shortly after the birth of the Solar System, Ultima Thule is revealed to be a contact binary, two connected sphere-like shapes held in contact by mutual gravity. Dubbed separately by the science team Ultima and Thule, the larger lobe Ultima is about 19 kilometers in diameter. Smaller Thule is 14 kilometers across.  News: New Horizons science results briefing
Ultima Thule Rotation Gif (2019-01-04)

Ultima Thule is the most distant world explored by a spacecraft from Earth. In the dim light 6.5 billion kilometers from the Sun, the New Horizons spacecraft captured these two frames 38 minutes apart as it sped toward the Kuiper belt world on January 1 at 51,000 kilometers per hour. A contact binary, the two lobes of Ultima Thule rotate together once every 15 hours or so. Shown as a blinking gif, the rotation between the frames produces a tantalizing 3D perspective of the most primitive world ever seen. Dubbed separately by the science team Ultima and Thule, the larger lobe Ultima, is about 19 kilometers in diameter. Smaller Thule is 14 kilometers across.
Yutu 2 on the Farside (2019-01-05)

On January 3, the Chinese Chang'e-4 spacecraft made the first successful landing on the Moon's farside. Taken by a camera on board the lander, this image is from the landing site inside Von Karman crater. It shows the desk-sized, six-wheeled Yutu 2 (Jade Rabbit 2) rover as it rolled down lander ramps and across the surface near local sunrise and the start of the two week long lunar day. Ripe for exploration, Von Karman crater itself is 186 kilometers in diameter. It lies within the Moon's old and deep South Pole-Aitken impact basin with some of the most ancient and least understood lunar terrains. To bridge communications from the normally hidden hemisphere of the Moon, China launched a relay satellite, Queqiao, in May of 2018 in to an orbit beyond the lunar farside.
A Laser Strike at the Galactic Center (2019-01-06)

Why are these people shooting a powerful laser into the center of our Galaxy?  Fortunately, this is not meant to be the first step in a Galactic war.  Rather, astronomers at the Very Large Telescope (VLT) site in Chile are trying to measure the distortions of Earth's ever changing atmosphere.  Constant imaging of high-altitude atoms excited by the laser -- which appear like an artificial star -- allow astronomers to instantly measure atmospheric blurring.  This information is fed back to a VLT telescope mirror which is then slightly deformed to minimize this blurring.  In this case, a VLT was observing our Galaxy's center, and so Earth's atmospheric blurring in that direction was needed.  As for inter-galaxy warfare, when viewed from our Galaxy's center, no casualties are expected.  In fact, the light from this powerful laser would combine with light from our Sun to together appear only as bright as a faint and distant star.    APOD in other languages: Arabic, Catalan, Chinese (Beijing), Chinese (Taiwan), Croatian, Czech, Dutch, German, French, French, Hebrew, Indonesian, Japanese, Korean, Montenegrin, Polish, Russian, Serbian, Slovenian and Spanish
Stars, Meteors, and a Comet in Taurus (2019-01-07)

This was an unusual night to look in the direction of the Bull. The constellation Taurus is always well known for hosting two bright star clusters -- the Pleaides, visible on the right, and the comparatively diffuse Hyades, visible on the left.  This night last month, however, was atypically the peak of the Geminid meteor shower, and so several meteors were caught shooting through the constellation with parallel trails. More unusually still, Comet Wirtanen was drifting through the constellation, here appearing near the image bottom surrounded by a greenish coma. The comet was near its brightest as it sped past the Earth. The orange star on the upper left is Aldebaran, considered to be the eye of the Bull. Aldebaran is the brightest star in Taurus and the 15th brightest star in the sky.  The featured image is a combination of nearly 800 exposures taken from the Spanish village Albany�.    Follow APOD on: Instagram, Facebook,  Reddit, or Twitter

Image credit: Juan Carlos Casado
HESS Telescopes Explore the High-Energy Sky (2019-01-08)

They may look like modern mechanical dinosaurs but they are enormous swiveling eyes that watch the sky. The High Energy Stereoscopic System (H.E.S.S.) Observatory is composed of four 12-meter reflecting-mirror telescopes surrounding a larger telescope housing a 28-meter mirror. They are designed to detect strange flickers of blue light -- Cherenkov radiation --emitted when charged particles move slightly faster than the speed of light in air.  This light is emitted when a gamma ray from a distant source strikes a molecule in Earth's atmosphere and starts a charged-particle shower.  H.E.S.S. is sensitive to some of the highest energy photons (TeV) crossing the universe.  Operating since 2003 in Namibia, H.E.S.S. has searched for dark matter and has discovered over 50 sources emitting high energy radiation including supernova remnants and the centers of galaxies that contain supermassive black holes.  Pictured last September, H.E.S.S. telescopes swivel and stare in time-lapse sequences shot in front of our Milky Way Galaxy and the Magellanic Clouds -- as the occasional Earth-orbiting satellite zips by.   Open Science: Browse 1,800+ codes in the Astrophysics Source Code Library

Image credit: Vikas Chander, 
H.E.S.S. Collaboration;
 Music:  Emotive Piano by 
Immersive Music
Quadrantids (2019-01-09)

Named for a forgotten constellation, the Quadrantid Meteor Shower is an annual event for planet Earth's northern hemisphere skygazers It usually peaks briefly in the cold, early morning hours of January 4. The shower's radiant on the sky lies within the old, astronomically obsolete constellation Quadrans Muralis. That position is situated near the boundaries of the modern constellations Hercules, Bootes, and Draco. About 30 Quadrantid meteors can be counted in this skyscape composed of digital frames recorded in dark and moonless skies between 2:30am and local dawn. The shower's radiant is rising just to the right of the Canary Island of Tenerife's Teide volcano, and just below the familiar stars of the Big Dipper on the northern sky. A likely source of the dust stream that produces Quadrantid meteors was identified in 2003 as an asteroid. Look carefully and you can also spot a small, telltale greenish coma above the volcanic peak and near the top of the frame. That's the 2018 Christmas visitor to planet Earth's skies, Comet Wirtanen.

Image credit: El Cielo de Canarias
Vela Supernova Remnant Mosaic (2019-01-10)

The plane of our Milky Way Galaxy runs through this complex and beautiful skyscape. Seen toward colorful stars near the northwestern edge of the constellation Vela (the Sails), the 16 degree wide, 200 frame mosaic is centered on the glowing filaments of the Vela Supernova Remnant, the expanding debris cloud from the death explosion of a massive star. Light from the supernova explosion that created the Vela remnant reached Earth about 11,000 years ago. In addition to the shocked filaments of glowing gas, the cosmic catastrophe also left behind an incredibly dense, rotating stellar core, the Vela Pulsar. Some 800 light-years distant, the Vela remnant is likely embedded in a larger and older supernova remnant, the Gum Nebula. Objects identified in this broad mosaic include emission and reflection nebulae, star clusters, and the remarkable Pencil Nebula.

Image credit: Robert Gendler
Partial Eclipse over Beijing (2019-01-11)

On January 6 the New Moon rose in silhouette with the Sun seen from northeastern Asia. Near maximum, the dramatic partial solar eclipse is captured in this telephoto view through hazy skies. In the foreground, the hill top Wanchun pavilion overlooking central Beijing's popular Forbidden City hosts eclipse-watching early morning risers. This was the first of five, three solar and two lunar, eclipses for 2019. Next up is a total lunar eclipse during this month's Full Perigee Moon. At night on January 21, that celestial shadow play will be visible from the hemisphere of planet Earth that includes the Americas, Europe, and western Africa.

Image credit: Li Zhaoqi
Milky Way Falls (2019-01-12)

It can be the driest place on planet Earth, but water still flows in Chile's Atacama desert, high in the mountains. After discovering this small creek with running water, the photographer returned to the site to watch the Milky Way rise in the dark southern skies, calculating the moment when Milky Way and precious flowing water would meet. In the panoramic night skyscape, stars and nebulae immersed in the glow along the Milky Way itself also shared that moment with the Milky Way's satellite galaxies the Large and Small Magellanic clouds above the horizon at the right. Bright star Beta Centauri is poised at the very top of the waterfall. Above it lies the dark expanse of the Coalsack nebula and the stars of the Southern Cross.

Image credit: Yuri Beletsky
Tycho's Supernova Remnant in X-ray (2019-01-13)

What star created this huge puffball?  What's pictured is the hot expanding nebula of Tycho's supernova remnant, the result of a stellar explosion first recorded over 400 years ago by the famous astronomer Tycho Brahe.  The featured image is a composite of three X-ray colors taken by the orbiting Chandra X-ray Observatory. The expanding gas cloud is extremely hot, while slightly different expansion speeds have given the cloud a puffy appearance.  Although the star that created SN 1572, is likely completely gone, a star dubbed Tycho G, too dim to be discerned here, is thought to be a companion. Finding progenitor remnants of Tycho's supernova is particularly important because the supernova is of Type Ia, an important rung in the distance ladder that calibrates the scale of the visible universe.   The peak brightness of Type Ia supernovas is thought to be well understood, making them quite valuable in exploring the relationship between faintness and farness in the distant universe.
Meteor and Milky Way over the Alps (2019-01-14)

Now this was a view with a thrill. From Mount Tschirgant in the Alps, you can see not only nearby towns and distant Tyrolean peaks, but also, weather permitting, stars, nebulas, and the band of the Milky Way Galaxy. What made the arduous climb worthwhile this night, though, was another peak -- the peak of the 2018 Perseids Meteor Shower. As hoped, dispersing clouds allowed a picturesque sky-gazing session that included many faint meteors, all while a carefully positioned camera took a series of exposures. Suddenly, a thrilling meteor -- bright and colorful -- slashed down right next the nearly vertical band of the Milky Way.  As luck would have it, the camera caught it too.  Therefore, a new image in the series was quickly taken with one of the sky-gazers posing on the nearby peak. Later, all of the images were digitally combined.

Image credit: Nicholas Roemmelt
(Venture Photography)