juliensimon/nasa-apod huggingface dataset:
Moonless Meteors and the Milky Way (2015-08-13)

Have you watched the Perseid meteor shower? Though the annual shower's predicted peak was last night, meteor activity should continue tonight (August 13/14), best enjoyed by just looking up in clear, dark skies after midnight. Of course, this year's Perseid shower has the advantage of being active near the August 14 New Moon. Since the nearly New Moon doesn't rise before the morning twilight many fainter meteors are easier to spot until then, with no interference from bright moonlight. The Perseid meteor shower last occurred near a New Moon in 2013. That's when the exposures used to construct this image were made, under dark, moonless skies from Hvar Island off the coast of Croatia. The widefield composite includes 67 meteors streaming from the heroic constellation Perseus, the shower's radiant, captured during 2013 August 8-14 against a background of faint zodiacal light and the Milky Way. The next moonless Perseid meteor shower will be in August 2018.

Image credit: Petr Horálek
Comet Dust over Enchanted Rock (2015-08-14)

Dusty debris from periodic Comet Swift-Tuttle was swept up by planet Earth this week. Vaporized by their passage through the dense atmosphere at 59 kilometers per second, the tiny grains produced a stream of Perseid meteors. A bright, colorful Perseid meteor flash was captured during this 20 second exposure. It made its ephemeral appearance after midnight on August 12, in the moonless skies over the broad granite dome of Enchanted Rock State Natural Area, central Texas, USA. Below the Perseid meteor, trees stand in silhouette against scattered lights along the horizon and the faint Milky Way, itself cut by dark clouds of interstellar dust.

Image credit: Jared Tennant
Perihelion Approaches (2015-08-15)

This dramatic outburst from the nucleus of Comet 67P/Churyumov-Gerasimenko occured on August 12, just hours before perihelion, its closest approach to the Sun. Completing an orbit of the Sun once every 6.45 years, perihelion distance for this periodic comet is about 1.3 astronomical units (AU), still outside the orbit of planet Earth (at 1 AU). The stark image of the 4 kilometer wide, double-lobed nucleus in bright sunlight and dark shadows was taken by the Rosetta spacecraft's science camera about 325 kilometers away. Too close to see the comet's growing tail, Rosetta maintains its ringside seat to watch the nucleus warm and become more active in coming weeks, as primordial ices sublimating from the surface produce jets of gas and dust. Of course, dust from the nucleus of periodic comet Swift-Tuttle, whose last perihelion passage was in 1992 at a distance of 0.96 AU, fell to Earth just this week.
M1: The Crab Nebula from Hubble (2015-08-16)

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 featured 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.   Students (of all ages): See free astronomy lectures online
Andromeda Rising over the Alps (2015-08-17)

Have you ever seen the Andromeda galaxy? Although M31 appears as a faint and fuzzy blob to the unaided eye, the light you see will be over two million years old, making it likely the oldest light you ever will see directly. Now rising near a few hours after sunset from mid-latitude northern locations, Andromeda is rising earlier each night and will be visible to northerners all night long starting in September. The featured image captured Andromeda rising above the Italian Alps last month. As cool as it may be to see this neighboring galaxy to our Milky Way with your own eyes, long duration camera exposures can pick up many faint and breathtaking details. Recent data indicates that our Milky Way Galaxy will collide and coalesce with the slightly larger Andromeda galaxy in a few billion years.   Follow APOD on: Facebook,  Google Plus, or Twitter

Image credit: Matteo Dunchi
Announcing Comet Catalina (2015-08-18)

Will Comet Catalina become visible to the unaided eye? Given the unpredictability of comets, no one can say for sure, but it seems like a good bet. The comet was discovered in 2013 by observations of the Catalina Sky Survey. Since then, Comet C/2013 US10 (Catalina) has steadily brightened and is currently brighter than 8th magnitude, making it visible with binoculars and long-duration camera images.  As the comet further approaches the inner Solar System it will surely continue to intensify, possibly becoming a naked eye object sometime in October and peaking sometime in late November. The comet will reside primarily in the skies of the southern hemisphere until mid-December, at which time its highly inclined orbit will bring it quickly into northern skies. Featured above,  Comet Catalina was imaged last week sporting a green coma and two growing tails.

Image credit: Ian Sharp
Central Cygnus Skyscape (2015-08-19)

In cosmic brush strokes of glowing hydrogen gas, this beautiful skyscape unfolds across the plane of our Milky Way Galaxy and the center of the northern constellation Cygnus the Swan. The featured image spans about six degrees. Bright supergiant star Gamma Cygni (Sadr) to the upper left of the image center lies in the foreground of the complex gas and dust clouds and crowded star fields. Left of Gamma Cygni, shaped like two luminous wings divided by a long dark dust lane is IC 1318, whose popular name is understandably the Butterfly Nebula. The more compact, bright nebula at the lower right is NGC 6888, the Crescent Nebula. Some distance estimates for Gamma Cygni place it at around 1,800 light-years while estimates for IC 1318 and NGC 6888 range from 2,000 to 5,000 light-years.

Image credit: Paul C. Swift
M27: Not a Comet (2015-08-20)

While hunting for comets in the skies above 18th century France, astronomer Charles Messier diligently kept a list of the things he encountered that were definitely not comets. This is number 27 on his now famous not-a-comet list. In fact, 21st century astronomers would identify it as a planetary nebula, but it's not a planet either, even though it may appear round and planet-like in a small telescope. Messier 27 (M27) is an excellent example of a gaseous emission nebula created as a sun-like star runs out of nuclear fuel in its core. The nebula forms as the star's outer layers are expelled into space, with a visible glow generated by atoms excited by the dying star's intense but invisible ultraviolet light. Known by the popular name of the Dumbbell Nebula, the beautifully symmetric interstellar gas cloud is over 2.5 light-years across and about 1,200 light-years away in the constellation Vulpecula. This impressive color composite highlights details within the well-studied central region and fainter, seldom imaged features in the nebula's outer halo. It incorporates broad and narrowband images recorded using filters sensitive to emission from sulfur, hydrogen and oxygen atoms.

Image credit: Francesco
di Biase
Sprites from Space (2015-08-21)

An old Moon and the stars of Orion rose above the eastern horizon on August 10. The Moon's waning crescent was still bright enough to be overexposed in this snapshot taken from another large satellite of planet Earth, the International Space Station. A greenish airglow traces the atmosphere above the limb of the planet's night. Below, city lights and lightning flashes from thunderstorms appear over southern Mexico. The snapshot also captures the startling apparition of a rare form of upper atmospheric lightning, a large red sprite caught above a lightning flash at the far right. While the space station's orbital motion causes the city lights to blur and trail during the exposure, the extremely brief flash of the red sprite is sharp. Now known to be associated with thunderstorms, much remains a mystery about sprites including how they occur, their effect on the atmospheric global electric circuit, and if they are somehow related to other upper atmospheric lightning phenomena such as blue jets or terrestrial gamma flashes.
Little Planet Curiosity (2015-08-22)

A curious robot almost completely straddles this rocky little planet. Of course, the planet is really Mars and the robot is the car-sized Curiosity Rover, posing over its recent drilling target in the Marias Pass area of lower Mount Sharp. The 92 images used to assemble the little planet projection, a digitally warped and stitched mosaic covering 360x180 degrees, were taken by the rover's Mars Hand Lens Imager (MAHLI) during the Curiosity mission sol (martian day) 1065.  That corresponds to 2015 August 5, three Earth years since Curiosity landed on the surface of the Red Planet. The composite selfie excludes images that show the rover's robotic arm and mount of the MAHLI camera itself, but their shadow is visible beneath. Check out this spectacular interactive version of Curiosity's sol 1065 panorama.
Giant Cluster Bends, Breaks Images (2015-08-23)

What are those strange blue objects?  Many of the brightest blue images are of a single, unusual, beaded, blue, ring-like galaxy which just happens to line-up behind a giant cluster of galaxies.  Cluster galaxies here typically appear yellow and -- together with the cluster's dark matter -- act as a gravitational lens.  A gravitational lens can create several images of background galaxies, analogous to the many points of light one would see while looking through a wine glass at a distant street light.  The distinctive shape of this background galaxy -- which is probably just forming -- has allowed astronomers to deduce that it has separate images at 4, 10, 11, and 12  o'clock, from the center of the cluster.  A blue smudge near the cluster center is likely another image of the same background galaxy.  In all, a recent analysis postulated that at least 33 images of 11 separate background galaxies are discernable.  This spectacular photo of galaxy cluster CL0024+1654 from the Hubble Space Telescope was taken in November 2004.
Dione, Rings, Shadows, Saturn (2015-08-24)

What's happening in this strange juxtaposition of moon and planet?  First and foremost, Saturn's moon Dione was captured here in a dramatic panorama by the robotic Cassini spacecraft currently orbiting the giant planet. The bright and cratered moon itself spans about 1100-km, with the large multi-ringed crater Evander visible on the lower right. Since the rings of Saturn are seen here nearly edge-on, they are directly visible only as a thin horizontal line that passes behind Dione. Arcing across the bottom of the image, however, are shadows of Saturn's rings, showing some of the rich texture that could not be seen directly. In the background, few cloud features are visible on Saturn.  The featured image was taken during the last planned flyby of Dione by Cassini, as the spacecraft is scheduled to dive into Saturn's atmosphere during 2017.   Teachers: Find classroom astronomy images through APOD's Index or Search engine.
Meteors and Milky Way over Mount Rainier (2015-08-25)

Despite appearances, the sky is not falling. Two weeks ago, however, tiny bits of comet dust were. Featured here is the Perseids meteor shower as captured over Mt. Rainier, Washington, USA.  The image was created from a two-hour time lapse video, snaring over 20 meteors, including one that brightened dramatically on the image left.  Although each meteor train typically lasts less than a second, the camera was able to capture their color progressions as they disintegrated in the Earth's atmosphere. Here an initial green tint may be indicative of small amounts of glowing magnesium atoms that were knocked off the meteor by atoms in the Earth's atmosphere.  To cap things off, the central band of our Milky Way Galaxy was simultaneously photographed rising straight up behind the snow-covered peak of Mt. Rainier. Another good meteor shower is expected in mid-November when debris from a different comet intersects Earth as the Leonids.   Follow APOD on Facebook: in English or Spanish

Image credit: Matthew Dieterich
Collinder 399: The Coat Hanger (2015-08-26)

Is this coat hanger a star cluster or an asterism?  This cosmic hang-up has been debated over much of last century, as astronomers wondered whether this binocular-visible object is really a physically associated open cluster or a chance projection. Chance star projections are known as asterisms, an example of which is the popular Big Dipper.  Recent precise measurements from different vantage points in the Earth's orbit around the Sun have uncovered discrepant angular shifts indicating that the Coat Hanger is better described as an asterism. Known more formally as Collinder 399, this bright stellar grouping is wider than the full moon and lies in the constellation of the Fox (Vulpecula).    APOD is also available in: Arabic, Bahasa Indonesian, Catalan, Chinese, Chinese, Czech, Dutch, Farsi, Farsi, Galego, German, French, Hebrew, Japanese, Korean, Montenegrin, Polish, Russian, Serbian, Slovenian, Spanish, Thai, or Turkish

Image credit: John Chumack
The Large Cloud of Magellan (2015-08-27)

The 16th century Portuguese navigator Ferdinand Magellan and his crew had plenty of time to study the southern sky during the first circumnavigation of planet Earth. As a result, two fuzzy cloud-like objects easily visible to southern hemisphere skygazers are known as the Clouds of Magellan, now understood to be satellite galaxies of our much larger, spiral Milky Way galaxy. About 160,000 light-years distant in the constellation Dorado, the Large Magellanic Cloud (LMC) is seen here in a remarkably deep, colorful, image. Spanning about 15,000 light-years or so, it is the most massive of the Milky Way's satellite galaxies and is the home of the closest supernova in modern times, SN 1987A.  The prominent patch below center is 30 Doradus, also known as the magnificent Tarantula Nebula, is a giant star-forming region about 1,000 light-years across.

Image credit: Carlos
Fairbairn
Puppis A Supernova Remnant (2015-08-28)

Driven by the explosion of a massive star, supernova remnant Puppis A is blasting into the surrounding interstellar medium about 7,000 light-years away. At that distance, this colorful telescopic field based on broadband and narrowband optical image data is about 60 light-years across. As the supernova remnant expands into its clumpy, non-uniform surroundings, shocked filaments of oxygen atoms glow in green-blue hues. Hydrogen and nitrogen are in red. Light from the initial supernova itself, triggered by the collapse of the massive star's core, would have reached Earth about 3,700 years ago. The Puppis A remnant is actually seen through outlying emission from the closer but more ancient Vela supernova remnant, near the crowded plane of our Milky Way galaxy. Still glowing across the electromagnetic spectrum Puppis A remains one of the brightest sources in the X-ray sky.

Image credit: Don Goldman
The Seagull Nebula (2015-08-29)

A broad expanse of glowing gas and dust presents a bird-like visage to astronomers from planet Earth, suggesting its popular moniker - The Seagull Nebula. This portrait of the cosmic bird covers a 1.6 degree wide swath across the plane of the Milky Way, near the direction of Sirius, alpha star of the constellation Canis Major. Of course, the region includes objects with other catalog designations: notably NGC 2327, a compact, dusty emission region with an embedded massive star that forms the bird's head (aka the Parrot Nebula, above center). Dominated by the reddish glow of atomic hydrogen, the complex of gas and dust clouds with bright young stars spans over 100 light-years at an estimated 3,800 light-year distance.

Image credit: Dieter Willasch
M31: The Andromeda Galaxy (2015-08-30)

What is the nearest major galaxy to our own Milky Way Galaxy?  Andromeda.  In fact, our Galaxy is thought to look much like Andromeda. Together these two galaxies dominate the Local Group of galaxies. The diffuse light from Andromeda is caused by the hundreds of billions of stars that compose it. The several distinct stars that surround Andromeda's image are actually stars in our Galaxy that are well in front of the background object. Andromeda is frequently referred to as M31 since it is the 31st object on Messier's list of diffuse sky objects. M31 is so distant it takes about two million years for light to reach us from there. Although visible without aid, the above image of M31 is a digital mosaic of 20 frames taken with a small telescope. Much about M31 remains unknown, including exactly how long it will before it  collides with our home galaxy.   Explore your Universe: Random APOD Generator

Image credit: Robert Gendler
Pluto in Enhanced Color (2015-08-31)

Pluto is more colorful than we can see. Color data and images of our Solar System's most famous dwarf planet, taken by the robotic New Horizons spacecraft during its flyby in July, have been digitally combined to give an enhanced view of this ancient world sporting an unexpectedly young surface. The featured enhanced color image is not only esthetically pretty but scientifically useful, making surface regions of differing chemical composition visually distinct. For example, the light-colored heart-shaped Tombaugh Regio on the lower right is clearly shown here to be divisible into two regions that are geologically different, with the leftmost lobe Sputnik Planum also appearing unusually smooth. New Horizons now continues on beyond Pluto, will continue to beam back more images and data, and will soon be directed to change course so that it can fly past asteroid 2014 MU69 in 2019 January.   Pluto Images with Brief Explanations: APOD Pluto Search
Distant Neutrinos Detected Below Antarctic Ice (2015-09-01)

From where do these neutrinos come? The IceCube Neutrino Observatory near the South Pole of the Earth has begun to detect nearly invisible particles of very high energy. Although these rarely-interacting neutrinos pass through much of the Earth just before being detected, where they started remains a mystery. Pictured here is IceCube's Antarctic lab accompanied by a cartoon depicting long strands of detectors frozen into the crystal clear ice below. Candidate origins for these cosmic neutrinos include the violent surroundings of supermassive black holes at the centers of distant galaxies, and tremendous stellar explosions culminating in supernovas and gamma ray bursts far across the universe. As IceCube detects increasingly more high energy neutrinos, correlations with known objects may resolve this cosmic conundrum -- or we may never know.   Astrophysicists: Browse 1,100+ codes in the Astrophysics Source Code Library
The Flare and the Galaxy (2015-09-02)

Is this person throwing a lightning bolt? No. Despite appearances, this person is actually pointing in the direction of a bright Iridium flare, a momentary reflection of sunlight off of a communications satellite in orbit around the Earth. As the Iridium satellite orbits, reflective antennas became aligned between the observer and the Sun to create a flash brighter than any star in the night sky. Iridium flares typically last several seconds, longer than most meteors. Also unlike meteors, the flares are symmetric and predictable. The featured flare involved Iridium satellite 15 and occurred over southern Estonia last week. In this well-planned image, a spectacular night sky appears in the background, complete with the central band of our Milky Way Galaxy running vertically up the image center.   Retrospective: Today in APOD History

Image credit: Martin Mark
Arp 159 and NGC 4725 (2015-09-03)

Pointy stars and peculiar galaxies span this cosmic snapshot, a telescopic view toward the well-groomed constellation Coma Berenices. Bright enough to show off diffraction spikes, the stars are in the foreground of the scene, well within our own Milky Way. But the two prominent galaxies lie far beyond our own, some 41 million light-years distant. Also known as NGC 4747, the smaller distorted galaxy at left is the 159th entry in the Arp Atlas of Peculiar Galaxies, with extensive tidal tails indicative of strong gravitational interactions in its past. At about a 100,000 light-years across, its likely companion on the right is the much larger NGC 4725. At first glance NGC 4725 appears to be a normal spiral galaxy, its central region dominated by the yellowish light of cool, older stars giving way to younger hot blue star clusters along dusty spiral outskirts. Still, NGC 4725 does look a little odd with only one main spiral arm.

Image credit: Stephen Leshin
Milky Way with Airglow Australis (2015-09-04)

After sunset on September 1, an exceptionally intense, reddish airglow flooded this Chilean winter night skyscape. Above a sea of clouds and flanking the celestial Milky Way, the airglow seems to ripple and flow across the northern horizon in atmospheric waves. Originating at an altitude similar to aurorae, the luminous airglow is instead due to chemiluminescence, the production of light through chemical excitation. Commonly captured with a greenish tinge by sensitive digital cameras, this reddish airglow emission is from OH molecules and oxygen atoms at extremely low densities and has often been present in southern hemisphere nights during the last few years. On this night it was visible to the eye, but seen without color. Antares and the central Milky Way lie near the top, with bright star Arcturus at left. Straddling the Milky Way close to the horizon are Vega, Deneb, and Altair, known in northern nights as the stars of the Summer Triangle.

Image credit: Yuri Beletsky
Atlas V Rising (2015-09-05)

rly morning risers along Florida's Space Coast, planet Earth, were treated to a launch spectacle on September 2nd. Before dawn an Atlas V rocket rose into still dark skies carrying a US Navy communications satellite from Cape Canaveral Air Force Station into Earth orbit. This minutes long exposure follows the rocket's arc climbing eastward over the Atlantic. As the rocket rises above Earth's shadow, its fiery trail becomes an eerie, noctilucent exhaust plume glinting in sunlight. Of course, the short, bright startrail just above the cloud bank is Venus rising, now appearing in planet Earth's skies as the brilliant morning star.

Image credit: Mike Deep
Earthrise (2015-09-06)

What's that rising over the edge of the Moon? Earth. About 47 years ago, in December of 1968, the Apollo 8 crew flew from the Earth to the Moon and back again. Frank Borman, James Lovell, and William Anders were launched atop a Saturn V rocket on December 21, circled the Moon ten times in their command module, and returned to Earth on December 27. The Apollo 8 mission's impressive list of firsts includes: the first humans to journey to the Earth's Moon, the first to fly using the Saturn V rocket, and the first to photograph the Earth from deep space.  As the Apollo 8 command module rounded the farside of the Moon, the crew could look toward the lunar horizon and see the Earth appear to rise, due to their spacecraft's orbital motion. Their famous picture of a distant blue Earth above the Moon's limb was a marvelous gift to the world.