juliensimon/nasa-apod huggingface dataset:
A February Moon's Halo (2012-02-11)

Lighting the night last Tuesday, February's Full Moon is sometimes called the Snow Moon. But the Moon was not quite full in this mosaicked skyscape recorded on February 2 south of Budapest, Hungary, and there was no snow either. Still, thin clouds of ice crystals hung in the cold, wintry sky creating this gorgeous lunar halo. Refraction of moonlight by the six-sided crystals produce the slightly colored halo with its characteristic radius of 22 degrees. Just below the Moon is bright star Aldebaran. Also well within the halo at the right is the Pleiades star cluster. At the lower left, near the halo's edge lie the stars of Orion with bright Capella, alpha star of the constellation Auriga, just beyond the halo near the top of the frame.

Image credit: Rafael Schmall
Orion in Gas, Dust, and Stars (2012-02-12)

The constellation of Orion holds much more than three stars in a row.  A deep exposure shows everything from dark nebula to star clusters, all embedded in an extended patch of gaseous wisps in the greater Orion Molecular Cloud Complex.  The brightest three stars on the far left are indeed the famous three stars that make up the belt of Orion.  Just below Alnitak, the lowest of the three belt stars, is the Flame Nebula, glowing with excited hydrogen gas and immersed in filaments of dark brown dust.  Below the frame center and just to the right of Alnitak lies the Horsehead Nebula, a  dark indentation of dense dust that has perhaps the most recognized nebular shapes on the sky. On the upper right lies M42, the Orion Nebula, an energetic caldron of tumultuous gas, visible to the unaided eye, that is giving birth to a new open cluster of stars.  Immediately to the left of M42 is a prominent bluish reflection nebula sometimes called the Running Man that houses many bright blue stars.  The above image, a digitally stitched composite taken over several nights, covers an area with objects that are roughly 1,500 light years away and spans about 75 light years.

Image credit: Rogelio Bernal Andreo
(Deep Sky Colors)
An Unusual Venusian Oval (2012-02-13)

Why would Venus appear oval? Venus has been seen countless times from the surface of the Earth, and every time the Earth's atmosphere has dispersed its light to some degree. When the air has just the right amount of dust or water droplets, small but distant objects like Venus appear spread out into an angularly large aureole. Aureoles are not unusual to see and are frequently noted as circular coronas around the Sun or Moon. Recently, however, aureoles have been imaged that are not circular but distinctly oval.  The above oval Venusian aureole was imaged by the astrophotographer who first noted the unusual phenomenon three years ago. Initially disputed, the unusual distortion has now been confirmed multiple times by several different astrophotographers. What causes the ellipticity is currently unknown, and although several hypotheses hold that horizontally oriented ice crystals are responsible, significant discussions about it are still taking place.

Image credit: Doug Zubenel
The Rosette Nebula (2012-02-14)

The Rosette Nebula is not the only cosmic cloud of gas and dust to evoke the imagery of flowers -- but it is the most famous.  At the edge of a large molecular cloud in Monoceros, some 5,000 light years away, the petals of this rose are actually a stellar nursery whose lovely, symmetric shape is sculpted by the winds and radiation from its central cluster of hot young stars. The stars in the energetic cluster, cataloged as NGC 2244, are only a few million years old, while the central cavity in the Rosette Nebula, cataloged as NGC 2237, is about 50 light-years in diameter. The nebula can be seen firsthand with a small telescope toward the constellation of the Unicorn (Monoceros).

Image credit: Brian Davis
Merope's Reflection Nebula (2012-02-15)

Reflection nebulas reflect light from a nearby star.  Many small carbon grains in the nebula reflect the light.  The blue color typical of reflection nebula is caused by blue light being more efficiently scattered by the carbon dust than red light.  The brightness of the nebula is determined by the size and density of the reflecting grains, and by the color and brightness of the neighboring star(s). NGC 1435, pictured above, surrounds Merope (23 Tau), one of the brightest stars in the Pleiades (M45).  The Pleiades nebulosity is caused by a chance encounter between an open cluster of stars and a dusty molecular cloud.

Image credit: Leonardo Orazi
NGC 5965 and NGC 5963 in Draco (2012-02-16)

These two spiral galaxies make a photogenic pair, found within the boundaries of the northern constellation Draco. Contrasting in color and orientation, NGC 5965 is nearly edge-on to our line of sight and dominated by yellow hues, while bluish NGC 5963 is closer to face-on. Of course, even in this well-framed cosmic snapshot the scene is invaded by other galaxies, including small elliptical NGC 5969 at the lower left. Brighter, spiky stars in our own Milky Way are scattered through the foreground. Though they seem to be close and of similar size, galaxies NGC 5965 and NGC 5963 are far apart and unrelated, by chance appearing close on the sky. NGC 5965 is about 150 million light-years distant and over 200,000 light-years across. Much smaller, NGC 5963 is a mere 40 million light-years away and so is not associated with the edge-on spiral. Difficult to follow, NGC 5963's extraordinarily faint blue spiral arms mark it as a low surface brightness galaxy.

Image credit: Stephen Leshin
At the West Wall of Aristarchus Crater (2012-02-17)

Aristarchus Plateau is anchored in the vast lava flows of the Moon's Oceanus Procellarum. At the plateau's southeastern edge lies the spectacular Aristarchus Crater, an impact crater 40 kilometers wide and 3 kilometers deep. Scan along this remarkable panorama and you will find yourself gazing directly at the crater's west wall for some 25 kilometers. Features along the terraced wall include dark impact melt and debris deposits, bright excavated material, and boulders over 100 meters wide. At a full resolution of 1.6 meters per pixel, the sharp mosaic was created from images recorded by the Lunar Reconnaissance Orbiter's narrow angle camera in November of 2011. The orbiter's vantage point was 70 kilometers east of the crater's center and only 26 kilometers above the lunar surface.
On the Road to Carina (2012-02-18)

This rugged road through the dark Atacama Desert seems to lead skyward toward the bright stars and glowing nebulae of the southern Milky Way. If you follow the road you will get to Cerro Armazones peak in Chile, future construction site for the 40-meter class European Extremely Large Telescope. For now though, sliding your cursor across the image will identify wonders of the southern skies in view. The scene is dominated by the reddish glow of the Great Carina Nebula, one of our galaxy's largest star forming regions. In fact, the remarkable skyscape is not a composite of varying exposures or a photomontage. Far from sources of light pollution, the landscape illuminated by starlight and the Milky Way above were recorded by a modified digital camera and fast lens. The sensitive system captured both planet Earth and deep sky in a relatively short exposure.

Image credit: Babak Tafreshi
A Message From Earth (2012-02-19)

What are these Earthlings trying to tell us?  The above message was broadcast from Earth towards the globular star cluster M13 in 1974.  During the dedication of the Arecibo Observatory - still the largest single radio telescope in the world - a string of 1's and 0's representing the above diagram was sent.   This attempt at extraterrestrial communication was mostly ceremonial - humanity regularly broadcasts radio and television signals out into space accidentally.  Even were this message received, M13 is so far away we would have to wait almost 50,000 years to hear an answer.   The above message gives a few simple facts about humanity and its knowledge: from left to right are numbers from one to ten, atoms including hydrogen and carbon, some interesting molecules, DNA, a human with description, basics of our Solar System, and basics of the sending telescope.  Several searches for extraterrestrial intelligence are currently underway, including one where you can use your own home computer.
Barred Spiral Galaxy NGC 1073 (2012-02-20)

Many spiral galaxies have bars across their centers.  Even our own Milky Way Galaxy is thought to have a modest central bar.  Prominently barred spiral galaxy NGC 1073, pictured above, was captured in spectacular detail in this recently released image taken by the orbiting Hubble Space Telescope. Visible are dark filamentary dust lanes, young  clusters of bright blue stars, red emission nebulas of glowing hydrogen gas, a long bright bar of stars across the center, and a bright active nucleus that likely houses a supermassive black hole.  Light takes about 55 million years to reach us from NGC 1073, which spans about 80,000 light years across.  NGC 1073 can be seen with a moderately-sized telescope toward the constellation of the Sea Monster  (Cetus),  Fortuitously, the above image not only caught the X-ray bright star system IXO 5, visible on the upper left and likely internal to the barred spiral, but three quasars far in the distance.
Anticrepuscular Rays Over Wyoming (2012-02-21)

What's happening over the horizon?  Although the scene may appear somehow supernatural, nothing more unusual is occurring than a setting Sun and some well placed clouds.  Pictured above are anticrepuscular rays.  To understand them, start by picturing common crepuscular rays that are seen any time that sunlight pours though scattered clouds. Now although sunlight indeed travels along straight lines, the projections of these lines onto the spherical sky are great circles.  Therefore, the crepuscular rays from a setting (or rising) sun will appear to re-converge on the other side of the sky.  At the anti-solar point 180 degrees around from the Sun, they are referred to as anticrepuscular rays.  Pictured above is a particularly striking set of anticrepuscular rays photographed last month near Cheyenne, Wyoming, USA.

Image credit: Nate Cassell
A Sailing Stone in Death Valley (2012-02-22)

How did this big rock end up on this strange terrain? One of the more unusual places here on Earth occurs inside Death Valley, California, USA.  There a dried lakebed named Racetrack Playa exists that is almost perfectly flat, with the odd exception of some very large stones, one of which is pictured above.  Now the flatness and texture of large playa like Racetrack are fascinating but not scientifically puzzling -- they are caused by mud flowing, drying, and cracking after a heavy rain.  Only recently, however, has a viable scientific hypothesis been given to explain how 300-kilogram sailing stones ended up near the middle of such a large flat surface.  Unfortunately, as frequently happens in science, a seemingly surreal problem ends up having a relatively mundane solution.  It turns out that high winds after a rain can push  even heavy rocks across a temporarily slick lakebed.
A Zodiacal Skyscape (2012-02-23)

Venus and Jupiter are this month's two brightest planets. Shortly after sunset on February 20, they dominate the sky above the western horizon and this snowy landscape. In clear and transparent skies over Cherry Springs State Park, Pennsylvania, USA, they are also seen immersed in Zodiacal light. The extended, diffuse, triangular glow is sunlight scattered by dust along the plane of the ecliptic. Brighter near the horizon, the Zodiacal glow angles upward, first to Venus and then to Jupiter hugging the ecliptic as they orbit the Sun. Fading even further, the glow stretches toward the lovely Pleides star cluster near the top of the frame. Following their appearance in this Zodiacal skyscape, the coming days will see Venus and Jupiter sharing the early evening sky with a young crescent Moon. The two bright planets are even headed for a close pairing or conjunction, separated by about 3 degrees on March 13.

Image credit: Jack Fusco
Aurigae Nebulae (2012-02-24)

Rich in star clusters and nebulae, the ancient constellation of Auriga, the Charioteer, rides high in northern winter night skies. Composed from narrow and broadband filter data and spanning nearly 8 Full Moons (4 degrees) on the sky, this deep telescopic view recorded in January shows off some of Auriga's celestial bounty. The field includes emission region IC 405 (top left) about 1,500 light-years distant. Also known as the Flaming Star Nebula, its red, convoluted clouds of glowing hydrogen gas are energized by hot O-type star AE Aurigae. IC 410 (top right) is significantly more distant, some 12,000 light-years away. The star forming region is famous for its embedded young star cluster, NGC 1893, and tadpole-shaped clouds of dust and gas. IC 417 and NGC 1931 at the lower right, the Spider and the Fly, are also young star clusters embedded in natal clouds that lie far beyond IC 405. Star cluster NGC 1907 is near the bottom edge of the frame, just right of center. The crowded field of view looks along the plane of our Milky Way galaxy, near the direction of the galactic anticenter.

Image credit: Steve
Cannistra
Stephan's Quintet (2012-02-25)

The first identified compact galaxy group, Stephan's Quintet is featured in this eye-catching image constructed with data drawn from the extensive Hubble Legacy Archive. About 300 million light-years away, only four of these five galaxies are actually locked in a cosmic dance of repeated close encounters. The odd man out is easy to spot, though. The interacting galaxies, NGC 7319, 7318A, 7318B, and 7317 have an overall yellowish cast. They also tend to have distorted loops and tails, grown under the influence of disruptive gravitational tides. But the predominantly bluish galaxy, NGC 7320, is closer, just 40 million light-years distant, and isn't part of the interacting group. Stephan's Quintet lies within the boundaries of the high flying constellation Pegasus. At the estimated distance of the quartet of interacting galaxies, this field of view spans about 500,000 light-years. However, moving just beyond this field, above and to the left, astronomers can identify another galaxy, NGC 7320C, that is also 300 million light-years distant. Of course, including it would bring the interacting quartet back up to quintet status.
The Mysterious Rings of Supernova 1987A (2012-02-26)

What's causing those odd rings in supernova 1987A?  Twenty five years ago, in 1987, the brightest supernova in recent history was seen in the Large Magellanic Cloud. At the center of the above picture is an object central to the remains of the violent stellar explosion. Surrounding the center are curious outer rings appearing as a flattened figure 8.  Although large telescopes including the Hubble Space Telescope monitor the curious rings every few years, their origin remains a mystery.  Pictured above is a Hubble image of the SN1987A remnant taken last year. Speculation into the cause of the rings includes beamed jets emanating from an otherwise hidden neutron star left over from the supernova, and the interaction of the wind from the progenitor star with gas released before the explosion.
Shocked by Supernova 1987A (2012-02-27)

Twenty five years ago, the brightest supernova of modern times was sighted. Over time, astronomers have watched and waited for the expanding debris from this tremendous stellar explosion to crash into previously expelled material.  A clear result of such a collision is demonstrated in the above time lapse video of images recorded by the Hubble Space Telescope between 1994 and 2009. The movie depicts the collision of an outward moving blast wave with the pre-existing, light-year wide ring.  The collision occurred at speeds near 60 million kilometers per hour and shock-heats the ring material causing it to glow.  Astronomers continue to study the collision as it illuminates the interesting past of SN 1987A, and provides clues to the origin of the mysterious rings.   Gallery: Jupiter-Venus-Moon Conjunction
The Opposing Tails of Comet Garradd (2012-02-28)

Why does Comet Garradd have two tails?  Visible on the left, Comet Garradd's dust tail is composed of ice and dust bits that trail the comet in its orbit around the Sun.  Visible on the right, Comet Garradd's ion tail, is composed of ionized gas blown directly out from the Sun by the solar wind. Most comets show two tails, although it is unusual for them to appear to point in nearly opposite directions. Comet Garradd is currently showing opposing tails because of the Earth's opportunistic intermediate viewing angle. Subtle hues in the above image captured last week show the dust tail as slightly yellow as its large grains reflecting sunlight achromatically, while the ion tail shines slightly blue as the carbon monoxide ions reflect blue sunlight more efficiently. In the center, surrounding the comet's nucleus, is the green-tinted coma, so colored as it is a mix of dust and gasses that include green-emitting cyanogen. Although now drifting out from the Sun, Comet Garradd will make its closest approach to the Earth next week.   Like: Follow APOD on Facebook or Google+

Image credit: Robert P�lzl
Moon and Planets Over Catalonia (2012-02-29)

Venus and Jupiter will appear unusually close in the sky over the next month. The planetary conjunction will be easily visible to the unaided eye because Venus will appear brighter than any background star, and Jupiter will be nearly as bright. To see the near-alignment, simply look to the west after sunset. At their closest, on March 15, the two planets will appear only about three degrees apart. The planets will not be significantly closer in space - Venus will just be passing nearly in front of Jupiter as seen from the Earth. In the above image composite taken late last week from Catalonia, Spain, a bright crescent moon appears to the right of Venus, while Jupiter appears near the top of the image.  The distant sun-illuminated spheres were photographed behind a sculpture depicting the legendary battle between a warrior and a dragon.  A gallery of conjunction images is visible on the Asterisk -- APOD's discussion board.  Please feel free to contribute. The next Jupiter-Venus conjunction will occur in May 2013.    Extra: Today is a Leap Day

Image credit: Juan Carlos Casado
Multicolor Venus (2012-03-01)

Brilliant Venus now shines in western skies at twilight. Seen as the prominent evening star, the planet is a tantalizing celestial beacon even for casual skygazers. Venus can offer less than satisfying telescopic views though. The planet is shrouded in reflective clouds that appear bright but featureless at the eyepiece. Still, careful imaging with a series of color filters, as used in these composite images, can reveal subtle cloud patterns. Captured early last month from a backyard observatory in Manchester, New Hampshire, USA, the images are based on video camera frames. The data was recorded through near-ultraviolet, green, and near-infrared filters (left), and red, green, and blue filters while Venus stood high above the western horizon just before sunset. This season's evening apparition of Venus is the best one for northern hemisphere observers in 7 years. It will ultimately end with a solar transit of the planet, the last one to occur in your lifetime, on June 5/6.

Image credit: SkyandTelescope.com
Jupiter Unplugged (2012-03-02)

Five hand drawn sketches of Jupiter were used to create this beautifully detailed flat map of the ruling gas giant's turbulent cloud tops. Made with colored pencils at the eyepiece of a 16 inch diameter telescope, the original drawings are about 5 inches (12.5 cm) in diameter. The drawn planisphere map dimensions are 16x8 inches (40x20 cm). Observing on different dates in November and December of 2011, astronomical artist Fred Burgeot has relied on Jupiter's rotation to cover the planet's complete circumference. Digital animator Pascal Chauvet has also translated Burgeot's drawings into an intriguing video (vimeo), synthesizing a telescopic view of the rotating planet with a tilt and phase appropriate for the observing dates. The video includes the Galilean moons moving along their orbits, beginning with Ganymede and Io casting shadows as they glide in front of Jupiter, followed by Europa and Callisto passing behind the planet's banded disk.

Image credit: Frédéric Burgeot
Another Tail for Comet Garradd (2012-03-03)

Remarkable comet Garradd (C2009/P1) has come to be known for two distinctive tails. From the perspective of earthbound comet watchers the tails are visible on opposite sides of its greenish coma. Seen here in a telescopic view, the recognizable dust tail fans out to the right, trailing the comet nucleus in its orbit. Streaming away from the sunward direction, a familiar bluish ion tail sweeps to the left. But the comet also seems to have, at least temporarily, sprouted a second ion tail recorded in this image from February 24. Other comet imagers have recently captured changing structures in Garradd's ion tail created as the plasma is buffeted by the magnetic fields in the solar wind. Now moving more quickly through northern skies, on March 5th comet Garradd will reach its closest approach to planet Earth, about 10.5 light-minutes distant.

Image credit: Olivier Sedan
Warped Spiral Galaxy ESO 510-13 (2012-03-04)

How did spiral galaxy ESO 510-13 get bent out of shape? The disks of many spirals are thin and flat, but not solid. Spiral disks are loose conglomerations of billions of stars and diffuse gas all gravitationally orbiting a galaxy center. A flat disk is thought to be created by sticky collisions of large gas clouds early in the galaxy's formation.  Warped disks are not uncommon, though, and even our own Milky Way Galaxy is thought to have a small warp.  The causes of spiral warps are still being investigated, but some warps are thought to result from interactions or even collisions between galaxies.  ESO 510-13, pictured above digitally sharpened, is about 150 million light years away and about 100,000 light years across.
Flying Over the Earth at Night (2012-03-05)

Many wonders are visible when flying over the Earth at night. A compilation of such visual spectacles was captured recently from the International Space Station (ISS) and set to rousing music. Passing below are white clouds, orange city lights, lightning flashes in thunderstorms, and dark blue seas.  On the horizon is the golden haze of Earth's thin atmosphere, frequently decorated by dancing auroras as the video progresses.  The green parts of auroras typically remain below the space station, but the station flies right through the red and purple auroral peaks. Solar panels of the ISS are seen around the frame edges. The ominous wave of approaching brightness at the end of each sequence is just the dawn of the sunlit half of Earth, a dawn that occurs every 90 minutes.   Quiz: Can you identify any of the landscapes?
NGC 2170: Celestial Still Life (2012-03-06)

Is this a painting or a photograph? In this beautiful celestial still life composed with a cosmic brush, dusty nebula NGC 2170 shines near the image center. Reflecting the light of nearby hot stars, NGC 2170 is joined by other bluish reflection nebulae, a red emission region, many dark absorption nebulae, and a backdrop of colorful stars. Like the common household items still life painters often choose for their subjects, the clouds of gas, dust, and hot stars pictured above are also commonly found in this setting - a massive, star-forming molecular cloud in the constellation of the Unicorn (Monoceros). The giant molecular cloud, Mon R2, is impressively close, estimated to be only 2,400 light-years or so away. At that distance, this canvas would be over 60 light-years across.

Image credit: Leonardo Julio & Carlos Milovic 
(Astronomia Pampeana)