juliensimon/nasa-apod huggingface dataset:
PanSTARRS: The Anti Tail Comet (2013-06-29)

Once known as Earth's sunset comet, PanSTARRS (C/2011 L4) is up all night now, but only for northern hemisphere skygazers. Telescopes are required to track its progress as it fades and heads for the outer solar system. But because planet Earth passed through the comet's orbital plane in late May, PanSTARRS will also be remembered for its remarkably long anti-tail. That edge-on perspective looking along the broad, fanned-out dust tail as it trailed behind the comet created the appearance of an anti-tail pointing in the sunward direction, back toward the inner solar system. Recorded on the night of May 27, this 13 pane mosaic (shown in positive and negative views) follows PanSTARRS' anti-tail as it stretches over 7 degrees from the comet's coma at the far right. The anti-tail was likely much longer, but gets lost in the evening's bright moonlight encroaching on the left edge of the scene. Background star cluster NGC 188 in Cepheus shows up along the way, near top left.

Image credit: Digital-Astronomy
Saturn's Hyperion: A Moon with Odd Craters (2013-06-30)

What lies at the bottom of Hyperion's strange craters?  Nobody's sure.  To help find out, the robot Cassini spacecraft now orbiting Saturn swooped past the sponge-textured moon in 2005 and 2010 and took images of unprecedented detail.  An image from the 2005 pass, shown above in false color, shows a remarkable world strewn with strange craters and a generally odd surface.   The slight differences in color likely show differences in surface composition.   At the bottom of most craters lies some type of unknown dark material.  Inspection of the image shows bright features indicating that the dark material might be only tens of meters thick in some places.   Hyperion is about 250 kilometers across,  rotates chaotically, and has a density so low that it might house a vast system of caverns inside.

Image credit: Cassini Imaging Team,
SSI,
JPL,
ESA,
NASA
Orbiting a Black Hole (2013-07-01)

What would it look like to orbit a black hole? Since the strong gravity of the black hole can significantly alter light paths, conditions would indeed look strange.  For one thing, the entire sky would be visible, since even stars behind the black hole would have their light bent to the observer's eye. For another, the sky near the black hole would appear significantly distorted, with more and more images of the entire sky visible increasingly near the black hole. Most visually striking, perhaps, is the outermost sky image completely contained inside an easily discernible circle known as the Einstein ring. Orbiting a black hole, as shown in the above scientifically-accurate computer-created illustrative video, will show stars that pass nearly directly behind the black hole as zipping around rapidly near the Einstein ring. Although star images near the Einstein ring may appear to move faster than light, no star is actually moving that quickly.  The above video is part of a sequence of videos visually exploring the space near a black hole's event horizon. (Disclosure: Video creator Robert Nemiroff is an editor for APOD.)

Image credit: Robert Nemiroff 
(MTU)
Circling a Black Hole at its Photon Sphere (2013-07-02)

What would it look like to go right up to a black hole? One particularly interesting place near a black hole is its photon sphere, where photons can orbit in circles, a sphere 50 percent further out than the event horizon. Were you to look out from the photon sphere of a black hole, half of the sky would appear completely black, half of the sky would appear unusually bright, and the back of your head would appear across the middle. The above computer-animated video depicts this view from the photon sphere. The reason that the lower region, as shown, appears black is because all light paths from this dark region comes up from the black hole -- which classically emits no light. The upper half of the sky now appears unusually bright, blueshifted, and shows increasingly many complete sky images increasingly close to the dark-light divide across the middle.  That dark-light divide is the photon sphere -- your location -- and since photons can do circles there, light from the back of your head can circle the black hole and come to your eye. No place on the sky is hidden from you -- stars that would normally pass behind the black hole now appear to zip quickly around an Einstein ring, a ring that appears above as a horizontal line about a quarter of the way down from the video top. The above video is part of a sequence of videos visually exploring the space near a black hole's event horizon.  (Disclosure: Video creator Robert Nemiroff is an editor for APOD.)

Image credit: Robert Nemiroff 
(MTU)
Stars and Lightning Over Greece (2013-07-03)

It may appear, at first, like the Galaxy is producing the lightning, but really it's the Earth. In the foreground of the above picturesque nighttime landscape is the Greek Island of Corfu, with town lights surrounding Lake Korrision. Visible farther in the distance are lights from the town of Preveza on the Greek mainland. In the more distant sky a thunderstorm is threatening, with two lightning strokes caught together during this 45 second wide-angle exposure taken in mid-May.  The lightning branch on the left appears to be striking near Preveza, whereas the lightning strike on the right appears to be striking near Mount Ainos on the Greek Island of Cephalonia.  Much farther in the distance, strewn about the sky, are hundreds of stars in the neighborhood of our Sun in the Milky Way Galaxy. Furthest away, arching over the entire panorama, are billions of stars that together compose the central band of our Milky Way.   News: YouTube video of yesterday's Russian rocket explosion

Image credit: Bill Metallinos
M82: Starburst Galaxy with a Superwind (2013-07-04)

Also known as the Cigar Galaxy for its elongated visual appearance, M82 is a starburst galaxy with a superwind. In fact, through ensuing supernova explosions and powerful winds from massive stars, the burst of star formation in M82 is driving a prodigious outflow. Evidence for the superwind from the galaxy's central regions is clear in this sharp telescopic snapshot. The composite image highlights emission from long outflow filaments of atomic hydrogen gas in reddish hues. Some of the gas in the superwind, enriched in heavy elements forged in the massive stars, will eventually escape into intergalactic space. Including narrow band image data in the deep exposure has revealed a faint feature dubbed the cap. Perched about 35,000 light-years above the galaxy at the upper left, the cap appears to be galactic halo material. The material has been ionized by the superwind shock or intense ultraviolet radiation from the young, massive stars in the galaxy's core. Triggered by a close encounter with nearby large galaxy M81, the furious burst of star formation in M82 should last about 100 million years or so. M82 is 12 million light-years distant, near the northern boundary of Ursa Major.

Image credit: Ken Crawford
Globular Star Cluster NGC 6752 (2013-07-05)

Some 13,000 light-years away toward the southern constellation Pavo, the globular star cluster NGC 6752 roams the halo of our Milky Way galaxy. Over 10 billion years old, NGC 6752 follows clusters Omega Centauri and 47 Tucanae as the third brightest globular in planet Earth's night sky. It holds over 100 thousand stars in a sphere about 100 light-years in diameter. Telescopic explorations of the NGC 6752 have found that a remarkable fraction of the stars near the cluster's core, are multiple star systems. They also reveal the presence of blue straggle stars, stars which appear to be too young and massive to exist in a cluster whose stars are all expected to be at least twice as old as the Sun. The blue stragglers are thought to be formed by star mergers and collisions in the dense stellar environment at the cluster's core. This sharp color composite also features the cluster's ancient red giant stars in yellowish hues.

Image credit: Damian Peach
NGC 6384: Spiral Beyond the Stars (2013-07-06)

The universe is filled with galaxies. But to see them astronomers must look out beyond the stars of our own galaxy, the Milky Way. This colorful Hubble Space Telescopic portrait features spiral galaxy NGC 6384, about 80 million light-years away in the direction of the constellation Ophiuchus. At that distance, NGC 6384 spans an estimated 150,000 light-years, while the Hubble close-up of the galaxy's central region is about 70,000 light-years wide. The sharp image shows details in the distant galaxy's blue star clusters and dust lanes along magnificent spiral arms, and a bright core dominated by yellowish starlight. Still, the individual stars seen in the picture are all in the relatively close foreground, well within our own galaxy. The brighter Milky Way stars show noticeable crosses, or diffraction spikes, caused by the telescope itself.
NGC 2170: Still Life with Reflecting Dust (2013-07-07)

In this beautiful celestial still life composed with a cosmic brush, dusty nebula NGC 2170 shines at the upper left. Reflecting the light of nearby hot stars, NGC 2170 is joined by other bluish reflection nebulae, a compact red emission region, and streamers of obscuring dust against a backdrop of stars. Like the common household items still life painters often choose for their subjects, the clouds of gas, dust, and hot stars pictured here 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 about 15 light-years across.   Follow APOD on: Facebook (Daily) (Sky) (Spanish) or Google Plus (Daily) (River)

Image credit: Adam Block
Pluto's Newly Discovered Moons Receive Names (2013-07-08)

Pluto's newly discovered moons now have names. Known previously as P4 and P5, the International Astronomical Union has now given the fourth and fifth discovered moons of Pluto the names Kerberos and Styx. The small moons were discovered in 2011 and 2012 by the Hubble Space Telescope in preparation for the close passing of the New Horizons spacecraft by Pluto in 2015. Kerberos is named for the many headed dog in Greek mythology that guards the entrance to the underworld, while Styx is named for the goddess who overlooks the mythological river that runs between the Earth and the underworld. Both monikers are related to the name of Pluto, who rules the mythical nether region. Because their reflectivity is unknown, the size of each moon is quite uncertain -- but each is crudely estimated to be about 20 kilometers in diameter.  The robotic New Horizons spacecraft is on schedule to pass by Pluto in 2015 and provide the first clear images of the dwarf planet and its companions.
Supergiant Star Gamma Cygni (2013-07-09)

Supergiant star Gamma Cygni lies at the center of the Northern Cross, a famous asterism in the constellation of the Swan (Cygnus). Known by the proper name Sadr, the bright star also lies at the center of this gorgeous skyscape, featuring a complex of stars, dust clouds, and glowing nebulae along the plane of our Milky Way galaxy. The field of view spans over 3 degrees (six Full Moons) on the sky and includes emission nebula IC 1318 and open star cluster NGC 6910. Left of Gamma Cygni and shaped like two glowing cosmic wings divided by a long dark dust lane, IC 1318's popular name is understandably the Butterfly Nebula. Above and slightly left of Gamma Cygni, are the young, still tightly grouped stars of NGC 6910. Some distance estimates for Gamma Cygni place it at around 1800 light-years while estimates for IC 1318 and NGC 6910 range from 2,000 to 5,000 light-years.

Image credit: Jose Francisco Hernandez 
(Altamira Observatory)
Large Sunspots Now Crossing the Sun (2013-07-10)

One of the largest sunspot regions in recent years is now crossing the Sun. This region of convoluted magnetic fields may well produce a solar flare that releases a cloud of energetic particles into the Solar System. Were a very powerful cloud to impact the Earth's magnetosphere, it could be dangerous to Earth-orbiting astronauts and satellites.  Conversely, the impact of even a less energetic cloud might create picturesque aurora.  Pictured above is the sunspot region as it appeared two days ago. The rightmost part of this region has been cataloged as AR 11785, while the left part as AR 11787. The darkest sunspot regions contain nearly vertical magnetic fields and are called umbras, while the surrounding bronze regions -- more clearly showing stringy magnetic flux tubes -- are called penumbras. Churning solar granules, many about 1000 km across, compose the yellow background region.  No one knows what this sunspot region will do, but space weather researchers are monitoring it closely.    Random APOD: Click here to surf the universe

Image credit: Damian Peach
Dusty Nebulae in Taurus (2013-07-11)

This complex of dusty nebulae linger along the edge of the Taurus molecular cloud, a mere 450 light-years distant. Stars are forming on the cosmic scene, including extremely youthful star RY Tauri prominent toward the upper left of the 1.5 degree wide telescopic field. In fact RY Tauri is a pre-main sequence star, embedded in its natal cloud of gas and dust, also cataloged as reflection nebula vdB 27. Highly variable, the star is still relatively cool and in the late phases of gravitational collapse. It will soon become a stable, low mass, main sequence star, a stage of stellar evolution achieved by our Sun some 4.5 billion years ago. Another pre-main sequence star, V1023 Tauri, can be spotted below and right, embedded in its yellowish dust cloud adjacent to the striking blue reflection nebula Ced 30.

Image credit: Bob Franke
Messier's Eleven (2013-07-12)

This fifteen degree wide field of view stretches across the crowded starfields of Sagittarius toward the center of our Milky Way galaxy. In fact, the center of the galaxy lies near the right edge of the rich starscape and eleven bright star clusters and nebulae fall near the center of the frame. All eleven are numbered entries in the catalog compiled by 18th century cosmic tourist Charles Messier. Gaining celebrity status with skygazers, M8 (Lagoon), M16 (Eagle), M17 (Omega), and M20 (Trifid) show off the telltale reddish hues of emission nebulae associated with star forming regions. But also eye-catching in small telescopes are star clusters in the crowded region; M18, M21, M22, M23, M25, and M28. Broader in extent than the star clusters themselves, M24 is actually a cloud of the Milky Way's stars thousands of light-years long, seen through a break in the galaxy's veil of obscuring dust. You can put your cursor over the image (or click here) for help identifying Messier's eleven.

Image credit: Fernando Cabrerizo
Sunspot at Sunset (2013-07-13)

Reddened rays of the setting Sun flooded the skies over Cedar Creek Lake, southeast of Dallas, Texas, planet Earth on July 6th. And while sunsets may be the most watched celestial event, this one even offered something extra. A sunspot so large it was visible to the naked eye is captured in the serene sunset view, near the center of a solar disk dimmed and distorted by Earth's dense atomosphere. Telescopic views revealed the spot to be a complex of large solar active regions composed of sunspots, some larger than planet Earth itself.

Image credit: Jo Hunter
The Pillars of Eagle Castle (2013-07-14)

What lights up this castle of star formation?  The familiar Eagle Nebula glows bright in many colors at once.  The above image is a composite of three of these glowing gas colors.  Pillars of dark dust nicely outline some of the denser towers of star formation.  Energetic light from young massive stars causes the gas to glow and effectively boils away part of the dust and gas from its birth pillar.  Many of these stars will explode after several million years, returning most of their elements back to the nebula which formed them.  This process is forming an open cluster of stars known as M16.   Random APOD: Click here to surf the universe

Image credit: Emanuele Colognato & Jim Wood
The Sombrero Galaxy from Hale (2013-07-15)

What's going on in the center of this spiral galaxy? Named the Sombrero Galaxy for its hat-like resemblance, M104 features a prominent dust lane and a bright halo of stars and globular clusters. Reasons for the Sombrero's hat-like appearance include an unusually large and extended central bulge of stars, and dark prominent dust lanes that appear in a disk that we see nearly edge-on. Billions of old stars cause the diffuse glow of the extended central bulge visible in the above image from the 200-inch Hale Telescope.  Close inspection of the central bulge shows many points of light that are actually globular clusters. M104's spectacular dust rings harbor many younger and brighter stars, and show intricate details astronomers don't yet fully understand.  The very center of the Sombrero glows across the electromagnetic spectrum, and is thought to house a large black hole.  Fifty million-year-old light from the Sombrero Galaxy can be seen with a small telescope towards the constellation of Virgo.   Astrophysicists: Browse 600+ codes in the Astrophysics Source Code Library

Image credit: Caltech/Palomar Observatory/Paul Gardner, 
Salvatore Grasso, and 
Ryan Hannahoe
The Moon from Zond 8 (2013-07-16)

Which moon is this? Earth's. Our Moon's unfamiliar appearance is due partly to an unfamiliar viewing angle as captured by a little-known spacecraft -- the Soviet Union's Zond 8 that circled the Moon in October of 1970. Pictured above, the dark-centered circular feature that stands out near the top of the image is Mare Orientale, a massive impact basin formed by an ancient collision with an asteroid. Mare Orientale is surrounded by light colored and highly textured highlands. Across the image bottom lies the dark and expansive Oceanus Procellarum, the largest of the dark (but dry) maria that dominate the side of the Moon that always faces toward the Earth. Originally designed to carry humans, robotic Zond 8 came within 1000 km of the lunar surface, took about 100 detailed photographs on film, and returned them safely to Earth within a week.   Follow APOD on: Facebook (Daily) (Sky) (Spanish) or Google Plus (Daily) (River)

Image credit: Galspace
A Waterspout in Florida (2013-07-17)

What's happening over the water?  Pictured above is one of the better images yet recorded of a waterspout, a type of tornado that occurs over water.  Waterspouts are spinning columns of rising moist air that typically form over warm water. Waterspouts can be as dangerous as tornadoes and can feature wind speeds over 200 kilometers per hour.  Some waterspouts form away from thunderstorms and even during relatively fair weather.  Waterspouts may be relatively transparent and initially visible only by an unusual pattern they create on the water.  The above image was taken earlier this month near Tampa Bay, Florida. The Atlantic Ocean off the coast of Florida is arguably the most active area in the world for waterspouts, with hundreds forming each year.  Some people speculate that waterspouts are responsible for some of the losses recorded in the Bermuda Triangle.

Image credit: Joey Mole
Hidden Galaxy IC 342 (2013-07-18)

Similar in size to large, bright spiral galaxies in our neighborhood, IC 342 is a mere 10 million light-years distant in the long-necked, northern constellation Camelopardalis. A sprawling island universe, IC 342 would otherwise be a prominent galaxy in our night sky, but it is hidden from clear view and only glimpsed through the veil of stars, gas and dust clouds along the plane of our own Milky Way galaxy. Even though IC 342's light is dimmed by intervening cosmic clouds, this deep telescopic image traces the galaxy's obscuring dust, blue star clusters, and glowing pink star forming regions along spiral arms that wind far from the galaxy's core. IC 342 may have undergone a recent burst of star formation activity and is close enough to have gravitationally influenced the evolution of the local group of galaxies and the Milky Way.  Interplanetary Group Photo op: Be sure to smile and wave at Saturn!

Image credit: Stephen Leshin
Take a Picture of Saturn (2013-07-19)

Take a picture of Saturn in the sky tonight. You could capture a view like this one. Recorded just last month looking toward the south, planet Earth and ruins of the ancient temple of Athena at Assos, Turkey are in the foreground. The Moon rises at the far left of the frame and Saturn is the bright "star" at the upper right, near Virgo's alpha star Spica (picture with labels). If you do take a picture of Saturn or wave at Saturn and take a picture, you can share it online and submit it to the Saturn Mosaic Project. Why take a picture tonight? Because the Cassini spacecraft will be orbiting Saturn and taking a picture of you.  Interplanetary News: Photo Op from Cassini and MESSENGER - just be sure to smile and wave.

Image credit: Tunç Tezel
Comet Lemmon and the Deep Sky (2013-07-20)

Now sweeping high above the ecliptic plane, Comet Lemmon has faded dramatically in planet Earth's night sky as it heads for the outer solar system. Some 16 light-minutes (2 AU) from the Sun, it still sports a greenish coma though, posing on the right in this 4 degree wide telescopic view from last Saturday with deep sky star clusters and nebulae in Cassiopeia. In fact, the rich background skyscape is typical within the boundaries of the boastful northern constellation that lie along the crowded starfields of the Milky Way. Included near center is open star cluster M52 about 5,000 light-years away. Around 11,000 light-years distant, the red glowing nebula NGC 7635 below and left of M52 is well-known for its appearance in close-up images as the Bubble Nebula. But the fading Comet Lemmon is not the only foreground object on the scene. A faint streak on the right is an orbiting satellite caught crossing through the field during the long exposure, glinting in the sunlight and winking out as it passes into Earth's shadow.  Interplanetary News: Photo Op from Cassini and MESSENGER - just be sure to smile and wave.

Image credit: Nick Martin
The Seasons of Saturn (2013-07-21)

Since Saturn's axis is tilted as it orbits the Sun, Saturn has seasons, like those of planet Earth ... but Saturn's seasons last for over seven years. So what season is it on Saturn now? Orbiting the equator, the tilt of the rings of Saturn provides quite a graphic seasonal display. Each year until 2016, Saturn's rings will be increasingly apparent after appearing nearly edge-on in 2009. The ringed planet is also well placed in evening skies providing a grand view as summer comes to Saturn's northern hemisphere and winter to the south. The Hubble Space Telescope took the above sequence of images about a year apart, starting on the left in 1996 and ending on the right in 2000.  Although they look solid, Saturn's Rings are likely less than 50 meters thick and consist of individually orbiting bits of ice and rock ranging in size from grains of sand to barn-sized boulders.   Follow APOD on: Facebook (Daily) (Sky) (Spanish) or Google Plus (Daily) (River)
Earth and Moon from Saturn (2013-07-22)

You are here.  Everyone you've ever known is here. Every human who has ever lived -- is here. Pictured above is the Earth-Moon system as captured by the Cassini mission orbiting Saturn in the outer Solar System. Earth is the brighter and bluer of the two spots near the center, while the Moon is visible to its lower right. Images of Earth from Saturn were taken on Friday. Quickly released unprocessed images were released Saturday showing several streaks that are not stars but rather cosmic rays that struck the digital camera while it was taking the image.  The above processed image was released earlier today.  At nearly the same time, many humans on Earth were snapping their own pictures of Saturn.   Note: Today's APOD has been updated.