juliensimon/nasa-apod huggingface dataset:
M1: The Crab Nebula from Hubble (2011-12-25)

This is the mess that is left when a star explodes.  The Crab Nebula, the result of a supernova seen in 1054 AD, is filled with mysterious filaments.  The filaments are not only tremendously complex, but appear to have less mass than expelled in the original supernova and a higher speed than expected from a free explosion.  The above image, taken by the Hubble Space Telescope, is presented in three colors chosen for scientific interest.  The Crab Nebula spans about 10 light-years.  In the nebula's very center lies a pulsar: a neutron star as massive as the Sun but with only the size of a small town.  The Crab Pulsar rotates about 30 times each second.   Best Short Astronomy Videos: APOD editor to speak in New York City on Friday, January 6
A Raging Storm System on Saturn (2011-12-26)

It is one of the largest and longest lived storms ever recorded in our Solar System.  First seen late last year, the above cloud formation in the northern hemisphere of Saturn started larger than the Earth and soon spread completely around the planet. The storm has been tracked not only from Earth but from up close by the robotic Cassini spacecraft currently orbiting Saturn. Pictured above in false colored infrared in February, orange colors indicate clouds deep in the atmosphere, while light colors highlight clouds higher up. The rings of Saturn are seen nearly edge-on as the thin blue horizontal line. The warped dark bands are the shadows of the rings cast onto the cloud tops by the Sun to the upper left. A source of radio noise from lightning, the intense storm may relate to seasonal changes as spring slowly emerges in the north of Saturn.   Fun Quiz: Celestial or Cellular -- can you tell the difference?
M27: The Dumbbell Nebula (2011-12-27)

The first hint of what will become of our Sun was discovered inadvertently in 1764. At that time, Charles Messier was compiling a list of diffuse objects not to be confused with comets. The 27th object on Messier's list, now known as M27 or the Dumbbell Nebula, is a planetary nebula, the type of nebula our Sun will produce when nuclear fusion stops in its core. M27 is one of the brightest planetary nebulae on the sky, and can be seen toward the constellation of the Fox (Vulpecula) with binoculars. It takes light about 1000 years to reach us from M27,  shown above in colors emitted by hydrogen and oxygen. Understanding the physics and significance of M27 was well beyond 18th century science. Even today, many things remain mysterious about bipolar planetary nebula like M27, including the physical mechanism that expels a low-mass star's gaseous outer-envelope, leaving an X-ray hot white dwarf.   Best Short Astronomy Videos: APOD editor to speak in New York City on Friday, January 6

Image credit: Bill Snyder
(Bill
Snyder Photography)
Comet Lovejoy over Paranal (2011-12-28)

Comet Lovejoy (C/2011 W3) survived its close encounter with the Sun earlier this month, taking its place among wonders of the southern skies just in time for Christmas. Seen here before sunrise from Paranal Observatory in Chile, the sungrazing comet's tails stretch far above the eastern horizon. Spanning over 20 degrees they rise alongside the plane of the our Milky Way galaxy. A breathtaking spectacle in itself, Lovejoy performs on this celestial stage with southern stars and nebulae, including the Large and Small Magellanic clouds right of the telescope dome, and the glow of zodiacal light along the left edge of the frame. With Paranal's Very Large Telescope units in the foreground, this wide-angle scene was captured on December 23. Receding from the Sun, Comet Lovejoy's tails have continued to grow in length even as the comet fades.

Image credit: Guillaume Blanchard
Conjunction at Sunset (2011-12-29)

While Comet Lovejoy entertained early morning risers in the southern hemisphere, a lovely conjunction of a young crescent Moon and Venus graced western skies at sunset. Captured on December 26th the conjunction, with beautiful sunset colors above and below, is seen here over Viverone Lake near Turin, Italy. But if you've been outdoors at all lately enjoying sunsets on planet Earth, then you've probably noticed Venus low in the west as the season's brilliant evening star. Sometimes mistaken for a terrestrial light near the horizon, Venus is the third brightest celestial beacon, after the Sun and Moon. That distinction is particularly easy to appreciate in this peaceful scene.

Image credit: Stefano De Rosa
The Diner at the Center of the Galaxy (2011-12-30)

The monster at the center of our Galaxy is about to get fed. Recent observations by the Very Large Telescopes indicate that a cloud of gas will venture too close to the supermassive black hole at the Galactic center. The gas cloud is being disrupted, stretched out, heated up, and some of it is expected to fall into the black hole over the next two years. In this artist's illustration, what remains of the blob after a close pass to the black hole is shown in red and yellow, arching out from the gravitational death trap to its right. The cloud's orbit is shown in red, while the orbits of central stars are shown in blue. The infalling nebula is estimated to contain several times the mass of our Earth, while the central black hole, thought to correspond to the radio source Sagittarius A*, contains about four million times the mass of our Sun. Once it falls in, nothing is expected to be heard from the doomed gas ever again.   Discovery + Outreach: Graduate student research position open for APOD
Comet Lovejoy and the ISS (2011-12-31)

On December 24, Comet Lovejoy rose in dawn's twilight, arcing above the eastern horizon, its tails swept back by the solar wind and sunlight. Seen on the left is the comet's early morning appearance alongside the southern Milky Way from the town of Intendente Alvear, La Pampa province, Argentina. The short star trails include bright southern sky stars Alpha and Beta Centauri near the center of the frame, but the long bright streak that crosses the comet tails is a little closer to home. Waiting for the proper moment to start his exposure, the photographer has also caught the International Space Station still glinting in the sunlight as it orbits (top to bottom) above the local horizon. The right panel is the near horizon view of Comet Lovejoy from the space station itself, captured only two days earlier. In fact, Dan Burbank, Expedition 30 commander, recorded Comet Lovejoy rising just before the Sun in a spectacular video (linked here). Even considering the other vistas available from low Earth orbit, Burbank describes the comet as "the most amazing thing I have ever seen in space."
To Fly Free in Space (2012-01-01)

At about 100 meters from the cargo bay of the space shuttle Challenger, Bruce McCandless II was farther out than anyone had ever been before.  Guided by a Manned Maneuvering Unit (MMU), astronaut McCandless, pictured above, was floating free in space. McCandless and fellow NASA astronaut Robert Stewart were the first to experience such an "untethered space walk" during Space Shuttle mission 41-B in 1984.  The MMU works by shooting jets of nitrogen and has since been used to help deploy and retrieve satellites.  With a mass over 140 kilograms, an MMU is heavy on Earth, but, like everything, is weightless when drifting in orbit. The MMU was replaced with the SAFER backpack propulsion unit.   Best Short Astronomy Videos: APOD editor to speak in New York City on Friday, January 6
Spot the Moon (2012-01-02)

Where's the full Moon? Somewhere in this image, the Earth's Moon is hiding.  The entire Moon is visible, in its completely full phase, in plain sight. Even the photographer's keen eye couldn't find it even though he knew exactly where to look -- only the long exposure of his camera picked it up -- barely.  Although by now you might be congratulating yourself on finding it, why was it so difficult to see? For one reason, this photograph was taken during the total lunar eclipse last month, when the Earth's shadow made the Moon much dimmer than a normal full Moon. For another, the image, taken in Colorado, USA, was captured just 12 minutes before sunrise. With the Moon on the exact opposite side of the sky from the Sun, this meant that the Sun was just below the horizon, but still slightly illuminating the sky. Last, as the Moon was only about two degrees above the horizon, the large volume of air between the camera and the horizon scattered a lot of light away from the background Moon. Twelve minutes after this image was acquired the Sun peeked over the horizon and the Moon set.   Discovery + Outreach: Graduate student research position open for APOD

Image credit: Jimmy Westlake
(Colorado Mountain College)
A Full Sky Aurora Over Norway (2012-01-03)

Higher than the highest building, higher than the highest mountain, higher than the highest airplane, lies the realm of the aurora.  Auroras rarely reach below 60 kilometers, and can range up to 1000 kilometers.  Aurora light results from energetic electrons and protons striking molecules in the Earth's atmosphere.  Frequently, when viewed from space, a complete aurora will appear as a circle around one of the Earth's magnetic poles.  The above wide angle image, horizontally compressed, captured an unexpected auroral display that stretched across the sky one month ago over eastern Norway.   Best Short Astronomy Videos: APOD editor to speak in New York City on Friday, January 6

Image credit: Sebastian Voltmer
Starburst Galaxy IC 10 (2012-01-04)

Lurking behind dust and stars near the plane of our Milky Way Galaxy, IC 10 is a mere 2.3 million light-years distant. Even though its light is dimmed by intervening dust, the irregular dwarf galaxy still shows off vigorous star-forming regions that shine with a telltale reddish glow in this colorful skyscape. In fact, also a member of the Local Group of galaxies, IC 10 is the closest known starburst galaxy. Compared to other Local Group galaxies, IC 10 has a large population of newly formed stars that are massive and intrinsically very bright, including a luminous X-ray binary star system thought to contain a black hole. Located within the boundaries of the northern constellation Cassiopeia, IC 10 is about 5,000 light-years across.   Best Short Astronomy Videos: APOD editor to speak in New York City on Friday, January 6

Image credit: Dietmar Hager
Ringside with Titan and Dione (2012-01-05)

Orbiting in the plane of Saturn's rings, Saturnian moons have a perpetual ringside view of the gorgeous gas giant planet. Of course, while passing near the ring plane the Cassini spacecraft also shares their stunning perspective. The rings themselves can be seen slicing across the middle of this Cassini snapshot from May of last year. The scene features Titan, largest, and Dione, third largest moon of Saturn. Remarkably thin, the bright rings still cast arcing shadows across the planet's cloud tops at the bottom of the frame. Pale Dione is about 1,100 kilometers across and orbits over 300,000 kilometers from the visible outer edge of the A ring. Dione is seen through Titan's atmospheric haze. At 5,150 kilometers across, Titan is about 2.3 million kilometers from Cassini, while Dione is 3.2 million kilometers away.   Best Short Astronomy Videos: APOD editor to speak in New York City on Friday, January 6
A Wide Field Image of the Galactic Center (2012-01-06)

From Sagittarius to Scorpius, the central Milky Way is a truly beautiful part of planet Earth's night sky. The gorgeous region is captured in this wide field image spanning about 30 degrees. The impressive cosmic vista, taken in 2010, shows off intricate dust lanes, bright nebulae, and star clusters scattered through our galaxy's rich central starfields. Starting on the left, look for the Lagoon and Trifid nebulae, the Cat's Paw, while on the right lies the Pipe dark nebula, and the colorful clouds of Rho Ophiuchi and Antares (right). The actual center of our Galaxy lies about 26,000 light years away and can be found here.   Discovery + Outreach: Graduate student research position open for APOD

Image credit: Ivan Eder
Grand Spiral Galaxy NGC 1232 (2012-01-07)

Galaxies are fascinating not only for what is visible, but for what is invisible. Grand spiral galaxy NGC 1232, captured in detail by one of the new Very Large Telescopes, is a good example.  The visible is dominated by millions of bright stars and dark dust, caught up in a gravitational swirl of spiral arms revolving about the center. Open clusters containing bright blue stars can be seen sprinkled along these spiral arms, while dark lanes of dense interstellar dust can be seen sprinkled between them. Less visible, but detectable, are billions of dim normal stars and vast tracts of interstellar gas, together wielding such high mass that they dominate the dynamics of the inner galaxy.  Invisible are even greater amounts of matter in a form we don't yet know - pervasive dark matter needed to explain the motions of the visible in the outer galaxy.    Discovery + Outreach: Graduate student research position open for APOD
Lighthouse and Meteor (2012-01-08)

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 point 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. Many of this year's Quadrantid meteors were dim, but the one captured in this north-looking view is bright and easy to spot. In the foreground is the Maurice River's East Point Lighthouse located near the southern tip of New Jersey on the US east coast. The likely source of the dust stream that produces Quadrantid meteors was identified in 2003 as an asteroid.

Image credit: Jack Fusco
Facing NGC 6946 (2012-01-09)

From our vantage point in the Milky Way Galaxy, we see NGC 6946 face-on. The big, beautiful spiral galaxy is located just 10 million light-years away, behind a veil of foreground dust and stars in the high and far-off constellation of Cepheus. From the core outward, the galaxy's colors change from the yellowish light of old stars in the center to young blue star clusters and reddish star forming regions along the loose, fragmented spiral arms. NGC 6946 is also bright in infrared light and rich in gas and dust, exhibiting a high star birth and death rate. In fact, since the early 20th century at least nine supernovae, the death explosions of massive stars, were discovered in NGC 6946. Nearly 40,000 light-years across, NGC 6946 is also known as the Fireworks Galaxy. This remarkable portrait of NGC 6946 is a composite that includes image data from the 8.2 meter Subaru Telescope on Mauna Kea.
Bright Star Regulus near the Leo I Dwarf Galaxy (2012-01-10)

The star near the top is so bright that it is sometimes hard to notice the galaxy toward the bottom.  Pictured above, both the star, Regulus, and the galaxy, Leo I, can be found within one degree of each other toward the constellation of the Lion (Leo).  Regulus is part of a multiple star system, with a close companion double star visible to the lower left of the young main sequence star.  Leo I is a dwarf spheroidal galaxy in the Local Group of galaxies dominated by our Milky Way Galaxy and M31. Leo I is thought to be the most distant of the several known small satellite galaxies orbiting our Milky Way Galaxy. Regulus is located about 75 light years away, in contrast to Leo 1 which is located about 800,000 light years away.   Discovery + Outreach: Graduate student research position open for APOD

Image credit: Chris Cook
(CookPhoto.com)
Little Planet Lovejoy (2012-01-11)

Once a bright apparition in the southern hemisphere dawn Comet Lovejoy is fading, but its long tail still stretches across skies near the south celestial pole. Captured on the morning of December 30th, the comet appears near edge of this little planet as well. Of course, the little planet is actually planet Earth and the image was created from a 12 frame mosaic used to construct a spherical panorama. The type of stereographic projection used to map the image pixels is centered directly below the camera and is known as the little planet projection. Stars surrounding this little planet were above the photographer's cloudy horizon near the Bay of Islands on the Great Ocean Road in southern Victoria, Australia. Running alongside the Milky Way the comet can be identified, with other celestial highlights, by putting your cursor over the picture. Very bright stars Canopus and Sirius are right of the little planet.

Image credit: Alex Cherney
(Terrastro,
TWAN)
The Case of the Missing Supernova Companion (2012-01-12)

Where's the other star? At the center of this supernova remnant should be the companion star to the star that blew up.  Identifying this star is important for understanding just how Type Ia supernova detonate, which in turn could lead to a better understanding of why the brightness of such explosions are so predictable, which in turn is key to calibrating the entire nature of our universe. The trouble is that even a careful inspection of the center of SNR 0509-67.5 has not found any star at all. This indicates that the companion is intrinsically very faint -- much more faint that many types of bright giant stars that had been previous candidates. In fact, the implication is that the companion star might have to be a faint white dwarf, similar to -- but less massive than -- the star that detonated.  SNR 0509-67.5 is shown above in both visible light, shining in red as imaged by the Hubble Space Telescope, and X-ray light, shown in false-color green as imaged by the Chandra X-ray Observatory. Putting your cursor over the picture will highlight the central required location for the missing companion star.   Discovery + Outreach: Graduate student research position open for APOD
Saturn's Iapetus: Painted Moon (2012-01-13)

What has happened to Saturn's moon Iapetus?  Vast sections of this strange world are dark as coal, while others are as bright as ice.  The composition of the dark material is unknown, but infrared spectra indicate that it possibly contains some dark form of carbon. Iapetus also has an unusual equatorial ridge that makes it appear like a walnut.  To help better understand this seemingly painted moon, NASA directed the robotic Cassini spacecraft orbiting Saturn to swoop within 2,000 kilometers in 2007. Pictured above, from about 75,000 kilometers out, Cassini's trajectory allowed unprecedented imaging of the hemisphere of Iapetus that is always trailing.  A huge impact crater seen in the south spans a tremendous 450 kilometers and appears superposed on an older crater of similar size. The dark material is seen increasingly coating the easternmost part of Iapetus, darkening craters and highlands alike.  Close inspection indicates that the dark coating typically faces the moon's equator and is less than a meter thick. A leading hypothesis is that the dark material is mostly dirt leftover when relatively warm but dirty ice sublimates. An initial coating of dark material may have been effectively painted on by the accretion of meteor-liberated debris from other moons. This and other images from Cassini's Iapetus flyby are being studied for even greater clues.   Discovery + Outreach: Graduate student research position open for APOD
NGC 6369: The Little Ghost Nebula (2012-01-14)

This pretty planetary nebula, cataloged as NGC 6369, was discovered by 18th century astronomer William Herschel as he used a telescope to explore the medicinal constellation Ophiucus. Round and planet-shaped, the nebula is also relatively faint and has acquired the popular moniker of Little Ghost Nebula. Planetary nebulae in general are not at all related to planets, but instead are created at the end of a sun-like star's life as its outer layers expand into space while the star's core shrinks to become a white dwarf. The transformed white dwarf star, seen near the center, radiates strongly at ultraviolet wavelengths and powers the expanding nebula's glow. Surprisingly complex details and structures of NGC 6369 are revealed in this tantalizing image composed from Hubble Space Telescope data. The nebula's main ring structure is about a light-year across and the glow from ionized oxygen, hydrogen, and nitrogen atoms are colored blue, green, and red respectively. Over 2,000 light-years away, the Little Ghost Nebula offers a glimpse of the fate of our Sun, which could produce its own planetary nebula only about 5 billion years from now.
Infrared Portrait of the Large Magellanic Cloud (2012-01-15)

Cosmic dust clouds ripple across this infrared portrait of our Milky Way's satellite galaxy, the Large Magellanic Cloud. In fact, the remarkable composite image from the Herschel Space Observatory and the Spitzer Space Telescope show that dust clouds fill this neighboring dwarf galaxy, much like dust along the plane of the Milky Way itself. The dust temperatures tend to trace star forming activity. Spitzer data in blue hues indicate warm dust heated by young stars. Herschel's instruments contributed the image data shown in red and green, revealing dust emission from cooler and intermediate regions where star formation is just beginning or has stopped. Dominated by dust emission, the Large Magellanic Cloud's infrared appearance is different from views in optical images. But this galaxy's well-known Tarantula Nebula still stands out, easily seen here as the brightest region to the left of center. A mere 160,000 light-years distant, the Large Cloud of Magellan is about 30,000 light-years across.
Zodiacal Light and the False Dawn (2012-01-16)

Is it dawn or false dawn? During certain times of the year, the horizon near the rising Sun will begin to glow unusually early. This early glow does not originate directly from the Sun, but rather from sunlight reflected by interplanetary dust. Called zodiacal light, the glowing triangle of light may be mistaken, for a while, for a sunrise, and so may be called a false dawn. Pictured above, two false dawns were recorded in time lapse movies each spanning about five hours from the perch of the highest observatory in the world: Mount Saraswati near Hanle, India. At its brightest, the rising zodiacal triangle on the left glows brighter than even the central disk of our Milky Way Galaxy -- visible as the diagonal band moving left to right across the frame.

Image credit: Nilesh Vayada & Ajay Talwar 
(TWAN)
IC 2118: The Witch Head Nebula (2012-01-17)

Double, double toil and trouble; Fire burn, and cauldron bubble -- maybe Macbeth should have consulted the Witch Head Nebula. This suggestively shaped reflection nebula is associated with the bright star Rigel in the constellation Orion. More formally known as IC 2118, the Witch Head Nebula glows primarily by light reflected from bright star Rigel, located just below the lower edge of the above image. Fine dust in the nebula reflects the light. The blue color is caused not only by Rigel's blue color but because the dust grains reflect blue light more efficiently than red. The same physical process causes Earth's daytime sky to appear blue, although the scatterers in Earth's atmosphere are molecules of nitrogen and oxygen. The nebula lies about 1000 light-years away.

Image credit: Gimmi Ratto & Davide Bardini
(Collecting Photons)