juliensimon/nasa-apod huggingface dataset:
Comet 45P Passes Near the Earth (2017-02-12)

A large snowball has just passed the Earth. Known as Comet 45P/Honda�Mrkos�Pajdu��kov�", or 45P for short, the comet came 10 times closer to Earth yesterday than the Earth ever gets to the Sun.  During this passage, the comet was photographed sporting a thin ion tail and a faint but expansive green coma. The green color is caused mostly by energized molecules of carbon. Comet 45P became just bright enough to see with the unaided eye when it came closest to the Sun in December. Now, however, the comet is fading as it heads back out to near the orbit of Jupiter, where it spends most of its time.  The kilometer-sized nucleus of ice and dirt will return to the inner Solar System in 2022.

Image credit: Fritz Helmut Hemmerich
Cloud Swirls around Southern Jupiter from Juno (2017-02-13)

Juno just completed its fourth pass near Jupiter. Launched from Earth in 2011 and arriving at Jupiter just last July, robotic Juno concluded its latest elliptical orbit around our Solar System's largest planet 11 days ago. Pictured here from that pass is a new high-resolution image of the southern hemisphere of Jupiter featuring a mesmerizing tapestry of swirling cloud systems. The terminator between day and night cuts diagonally across the bottom, meaning that the Sun is positioned off the top right.  Large Oval BA is visible in orange on the far right. Reasons for the details and colors of Jupiter's cloud swirls are currently unknown. Juno's planned six year mission will study Jovian giant in new ways, including trying to determine if beneath its thick clouds, Jupiter has a solid core.
The Rosette Nebula (2017-02-14)

Would the Rosette Nebula by any other name look as sweet? The bland New General Catalog designation of NGC 2237 doesn't appear to diminish the appearance of  this flowery emission nebula. Inside the nebula lies an open cluster of bright young stars designated NGC 2244. These stars formed about four million years ago from the nebular material and their stellar winds are clearing a hole in the nebula's center, insulated by a layer of dust and hot gas. Ultraviolet light from the hot cluster stars causes the surrounding nebula to glow. The Rosette Nebula spans about 100 light-years across, lies about 5000 light-years away, and can be seen with a small telescope towards the constellation of the Unicorn (Monoceros).

Image credit: Evangelos Souglakos
The Calabash Nebula from Hubble (2017-02-15)

Fast expanding gas clouds mark the end for a central star in the Calabash Nebula.  The once-normal star has run out of nuclear fuel, causing the central regions to contract into a white dwarf.  Some of the liberated energy causes the outer envelope of the star to expand.  In this case, the result is a photogenic proto-planetary nebula.  As the million-kilometer per hour gas rams into the surrounding interstellar gas, a supersonic shock front forms where ionized hydrogen and nitrogen glow blue.  Thick gas and dust hide the dying central star.  The Calabash Nebula, also known as the Rotten Egg Nebula and OH231.8+4.2, will likely develop into a full bipolar planetary nebula over the next 1000 years.  The nebula, featured here, is about 1.4 light-years in extent and located about 5000 light-years away toward the constellation of Puppis.
The Tulip and Cygnus X-1 (2017-02-16)

Framing a bright emission region, this telescopic view looks out along the plane of our Milky Way Galaxy toward the nebula rich constellation Cygnus the Swan. Popularly called the Tulip Nebula, the reddish glowing cloud of interstellar gas and dust is also found in the 1959 catalog by astronomer Stewart Sharpless as Sh2-101. About 8,000 light-years distant and 70 light-years across the complex and beautiful nebula blossoms at the center of this composite image. Ultraviolet radiation from young energetic stars at the edge of the Cygnus OB3 association, including O star HDE 227018, ionizes the atoms and powers the emission from the Tulip Nebula. HDE 227018 is the bright star near the center of the nebula. Also framed in the field of view is microquasar Cygnus X-1, one of the strongest X-ray sources in planet Earth's sky. Driven by powerful jets from a black hole accretion disk, its fainter visible curved shock front lies above and right, just beyond the cosmic Tulip's petals

Image credit: Ivan Eder
Polar Ring Galaxy NGC 660 (2017-02-17)

NGC 660 is featured in this cosmic snapshot. Over 40 million light-years away and swimming within the boundaries of the constellation Pisces, NGC 660's peculiar appearance marks it as a polar ring galaxy. A rare galaxy type, polar ring galaxies have a substantial population of stars, gas, and dust orbiting in rings strongly tilted from the plane of the galactic disk. The bizarre-looking configuration could have been caused by the chance capture of material from a passing galaxy by a disk galaxy, with the captured debris eventually strung out in a rotating ring. The violent gravitational interaction would account for the myriad pinkish star forming regions scattered along NGC 660's ring. The polar ring component can also be used to explore the shape of the galaxy's otherwise unseen dark matter halo by calculating the dark matter's gravitational influence on the rotation of the ring and disk. Broader than the disk, NGC 660's ring spans over 50,000 light-years.

Image credit: CHART32 Team
Penumbral Eclipse Rising (2017-02-18)

As seen from Cocoa Beach Pier, Florida, planet Earth, the Moon rose at sunset on February 10 while gliding through Earth's faint outer shadow. In progress was the first eclipse of 2017, a penumbral lunar eclipse followed in this digital stack of seaside exposures. Of course, the penumbral shadow is lighter than the planet's umbral shadow. That central, dark, shadow is easily seen on the lunar disk during a total or partial lunar eclipse. Still, in this penumbral eclipse the limb of the Moon grows just perceptibly darker as it rises above the eastern horizon. The second eclipse of 2017 could be more dramatic though. With viewing from a path across planet Earth's southern hemisphere, on February 26 there will be an annular eclipse of the Sun.

Image credit: Bill Jelen
Black Sun and Inverted Starfield (2017-02-19)

Does this strange dark ball look somehow familiar? If so, that might be because it is our Sun. In the featured image from 2012, a detailed solar view was captured originally in a very specific color of red light, then rendered in black and white, and then color inverted. Once complete, the resulting image was added to a starfield, then also color inverted. Visible in the image of the Sun are long light filaments, dark active regions, prominences peeking around the edge, and a moving carpet of hot gas. The surface of our Sun can be a busy place, in particular during Solar Maximum, the time when its surface magnetic field is wound up the most. Besides an active Sun being so picturesque, the plasma expelled can also become picturesque when it impacts the Earth's magnetosphere and creates auroras.    Follow APOD on: Facebook,  Google Plus,  Instagram, or Twitter

Image credit: Jim Lafferty
Almost Three Tails for Comet Encke (2017-02-20)

How can a comet have three tails? Normally, a comet has two tails: an ion tail of charged particles emitted by the comet and pushed out by the wind from the Sun, and a dust tail of small debris that orbits behind the comet but is also pushed out, to some degree, by the solar wind.  Frequently a comet will appear to have only one tail because the other tail is not easily visible from the Earth.  In the featured unusual image, Comet 2P/Encke appears to have three  tails because the ion tail split just near to the time when the image was taken. The complex solar wind is occasionally turbulent and sometimes creates unusual structure in an ion tail. On rare occasions even ion-tail disconnection events have been recorded. An image of the Comet Encke taken two days later gives a perhaps less perplexing perspective.

Image credit: Fritz Helmut Hemmerich
An Active Night over the Magellan Telescopes (2017-02-21)

The night sky is always changing.  Featured here are changes that occurred over a six hour period in late 2014 June behind the dual 6.5-meter Magellan Telescopes at Las Campanas Observatory in Chile. The initial red glow on the horizon is airglow, a slight cooling of high air by the emission of specific colors of light. Bands of airglow are also visible throughout the time-lapse video. Early in the night, car headlights flash on the far left.  Satellites quickly shoot past as they circle the Earth and reflect sunlight. A long and thin cloud passes slowly overhead.  The Small Magellanic Cloud rises on the left, while the expansive central band of our Milky Way Galaxy arches and pivots as the Earth rotates.  As the night progresses, the Magellan telescopes swivel and stare as they explore pre-determined patches of the night sky. Every night, every sky changes differently, even though the phenomena at play are usually the same.   Explore the Universe: Random APOD Generator

Image credit: Yuri Beletsky
(Carnegie
Las Campanas Observatory,
TWAN); 
 Music Credit & License: 
Airglow by 
Club 220
Daphnis and the Rings of Saturn (2017-02-22)

What's happening to the rings of Saturn? Nothing much, just a little moon making waves. The moon is 8-kilometer Daphnis and it is making waves in the Keeler Gap of Saturn's rings using just its gravity -- as it bobs up and down, in and out.  The featured image is a wide-field version of a previously released image taken last month by the robotic Cassini spacecraft during one of its new Grand Finale orbits. Daphnis can be seen on the far right, sporting ridges likely accumulated from ring particles.  Daphnis was discovered in Cassini images in 2005 and raised mounds of ring particles so high in 2009 -- during Saturn's equinox when the ring plane pointed directly at the Sun -- that they cast notable shadows.
Seven Worlds for TRAPPIST-1 (2017-02-23)

Seven worlds orbit the ultracool dwarf star TRAPPIST-1, a mere 40 light-years away. In May 2016 astronomers using the Transiting Planets and Planetesimals Small Telescope (TRAPPIST) announced the discovery of three planets in the TRAPPIST-1 system. Just announced, additional confirmations and discoveries by the Spitzer Space Telescope and supporting ESO ground-based telescopes have increased the number of known planets to seven. The TRAPPIST-1 planets are likely all rocky and similar in size to Earth, the largest treasure trove of terrestrial planets ever detected around a single star. Because they orbit very close to their faint, tiny star they could also have regions where surface temperatures allow for the presence of liquid water, a key ingredient for life. Their tantalizing proximity to Earth makes them prime candidates for future telescopic explorations of the atmospheres of potentially habitable planets.  All seven worlds appear in this artist's illustration, an imagined view from a fictionally powerful telescope near planet Earth. Planet sizes and relative positions are drawn to scale for the Spitzer observations. The system's inner planets are transiting their dim, red, nearly Jupiter-sized parent star.
NGC 3621: Far Beyond the Local Group (2017-02-24)

Far beyond the local group of galaxies lies NGC 3621, some 22 million light-years away. Found in the multi-headed southern constellation Hydra, the winding spiral arms of this gorgeous island universe are loaded with luminous blue star clusters, pinkish starforming regions, and dark dust lanes. Still, for astronomers NGC 3621 has not been just another pretty face-on spiral galaxy. Some of its brighter stars have been used as standard candles to establish important estimates of extragalactic distances and the scale of the Universe. This beautiful image of NGC 3621, is a composite of space- and ground-based telescope data. It traces the loose spiral arms far from the galaxy's brighter central regions for some 100,000 light-years. Spiky foreground stars in our own Milky Way Galaxy and even more distant background galaxies are scattered across the colorful skyscape.

Image credit: Robert Gendler
All Planets Panorama (2017-02-25)

For 360 degrees, a view along the plane of the ecliptic is captured in this remarkable panorama, with seven planets in a starry sky. The mosaic was constructed using images taken during January 24-26, from Nacpan Beach, El Nido in Palawan, Philippines. It covers the eastern horizon (left) in dark early morning hours and the western horizon in evening skies. While the ecliptic runs along the middle traced by a faint band of zodiacal light, the Milky Way also cuts at angles through the frame. Clouds and the Moon join fleeting planet Mercury in the east. Yellowish Saturn, bright star Antares, and Jupiter lie near the ecliptic farther right. Hugging the ecliptic near center are Leo's alpha star Regulus and star cluster M44. The evening planets gathered along the ecliptic above the western horizon, are faint Uranus, ruddy Mars, brilliant Venus, and even fainter Neptune. A well labeled version of the panorama can be viewed by sliding your cursor over the picture, or just following this link.

Image credit: Tunç Tezel
A Supercell Thunderstorm Cloud Over Montana (2017-02-26)

Is that a spaceship or a cloud? Although it may seem like an alien mothership, it's actually a impressive thunderstorm cloud called a supercell. Such colossal storm systems center on mesocyclones -- rotating updrafts that can span several kilometers and deliver torrential rain and high winds including tornadoes.  Jagged sculptured clouds adorn the supercell's edge, while wind swept dust and rain dominate the center.  A tree waits patiently in the foreground.    The above supercell cloud was photographed in 2010 July west of Glasgow, Montana, USA, caused minor damage, and lasted several hours before moving on.   Today: Southern Hemisphere Solar Eclipse

Image credit: Sean R. Heavey
Four Quasar Images Surround a Galaxy Lens (2017-02-27)

An odd thing about the group of lights near the center is that four of them are the same distant quasar.  This is because the foreground galaxy -- in the center of the quasar images and the featured image -- is acting like a choppy gravitational lens. A perhaps even odder thing is that by watching these background quasars flicker, you can estimate the expansion rate of the universe.  That is because the flicker timing increases as the expansion rate increases.  But to some astronomers, the oddest thing of all is that these multiply imaged quasars indicate a universe that is expanding a bit faster than has been estimated by different methods that apply to the early universe. And that is because ... well, no one is sure why.  Reasons might include an unexpected distribution of dark matter, some unexpected effect of gravity, or something completely different.  Perhaps future observations and analyses of this and similarly lensed quasar images will remove these oddities.
A White Oval Cloud on Jupiter from Juno (2017-02-28)

This storm cloud on Jupiter is almost as large as the Earth.  Known as a white oval, the swirling cloud is a high pressure system equivalent to an Earthly anticyclone. The cloud is one of a "string of pearls" ovals south of Jupiter's famous Great Red Spot.  Possibly, the Great Red Spot is just a really large white oval that turned red.  Surrounding clouds show interesting turbulence as they flow around and past the oval.  The featured image was captured on February 2 as NASA's robotic spacecraft Juno made a new pass just above the cloud tops of the Jovian world.  Over the next few years, Juno will continue to orbit and probe Jupiter, determine atmospheric water abundance, and attempt to determine if Jupiter has a solid surface beneath its thick clouds.
A Solar Eclipse with a Beaded Ring of Fire (2017-03-01)

What kind of eclipse is this? On Sunday, visible in parts of Earth's southern hemisphere, the Moon blocked part of the Sun during a partial solar eclipse. In some locations, though, the effect was a rare type of partial eclipse called an annular eclipse. There, since the Moon is too far from the Earth to block the entire Sun, sunlight streamed around the edges of the Moon creating a "ring of fire". At some times, though, the effect was a rare type of annular eclipse. Then, an edge of the Moon nearly aligned with an edge of the Sun, allowing sunlight to stream through only low areas on the Moon.  Called a "Baily's bead" or a "diamond ring", this doubly rare effect was captured Sunday in the feature photograph from Chubut, Argentina, in South America. This summer a total solar eclipse will swoop across North America.   Almost Hyperspace: Random APOD Generator

Image credit: Stephen Bedingfield
Annular Eclipse After Sunrise (2017-03-02)

From northern Patagonia, morning skies were clear and blue on Sunday, February 26. This sweeping composite scene, overlooking Hermoso Valle, Facundo, Chubut, Argentina, follows the Sun after sunrise, capturing an annular solar eclipse. Created from a series of exposures at three minute intervals, it shows the year's first solar eclipse beginning well above the distant eastern horizon. An exposure close to mid-eclipse recorded the expected ring of fire, the silhouette of the New Moon only slightly too small to cover the bright Sun. At that location on planet Earth, the annular phase of the eclipse lasted a brief 45 seconds.

Image credit: Vincent Bouchama
Sivan 2 to M31 (2017-03-03)

From within the boundaries of the constellation Cassiopeia (left) to Andromeda (right), this telescopic mosaic spans over 10 degrees in planet Earth's skies. The celestial scene is constructed of panels that are part of a high-resolution astronomical survey of the Milky Way in hydrogen-alpha light. Processing the monochromatic image data has brought out the region's faintest structures, relatively unexplored filaments of hydrogen gas near the plane of our Milky Way Galaxy. Large but faint and also relatively unknown nebula Sivan 2 is at the upper left in the field. The nearby Andromeda Galaxy, M31, is at center right, while the faint, pervasive hydrogen nebulosities stretch towards M31 across the foreground in the wide field of view. The broad survey image demonstrates the intriguing faint hydrogen clouds recently imaged by astronomer Rogelio Bernal Andreo really are within the Milky Way, along the line-of-sight to the Andromeda Galaxy.

Image credit: MDW Sky Survey
NGC 2170: Still Life with Reflecting Dust (2017-03-04)

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.

Image credit: Adam Block
The Mysterious Rings of Supernova 1987A (2017-03-05)

What's causing those odd rings in supernova 1987A?  Thirty years ago, in 1987, the brightest supernova in recent history was seen in the Large Magellanic Cloud. At the center of the featured 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 here is a Hubble image of the SN1987A remnant taken in 2011. 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.
Colorful Aurora over Iceland (2017-03-06)

You don't always see a scene this beautiful when you hike to an ancient volcano -- you have to be lucky.  When the astrophotographer realized that auroras were visible two-weeks ago, he made a night-time run for the top of the caldera to see if he could capture them also reflected in the central lake. When he arrived, he found that ... the northern lights were even brighter and more impressive than before! And his image of them is the featured 13-frame panoramic mosaic.  The crater lake in the center is called Kerid (Icelandic: Keri�) and is about 3,000 years old. The aurora overhead shows impressive colors and banding, with the red colors occurring higher in the Earth's atmosphere than the green. The background sky is filled with icons of the northern night including Polaris, the Pleiades star cluster, and the stars that compose the handle of the Big Dipper.    Follow APOD on: Facebook,  Google Plus,  Instagram, or Twitter

Image credit: Sigurdur William Brynjarsson;
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UGC 12591: The Fastest Rotating Galaxy Known (2017-03-07)

Why does this galaxy spin so fast?  To start, even identifying which type of galaxy UGC 12591 is difficult -- it has dark dust lanes like a spiral galaxy but a large diffuse bulge of stars like a lenticular. Surprisingly observations show that UGC 12591 spins at about 480 km/sec, almost twice as fast as our Milky Way, and the fastest rotation rate yet measured.  The mass needed to hold together a galaxy spinning this fast is several times the mass of our Milky Way Galaxy. Progenitor scenarios for UGC 12591 include slow growth by accreting ambient matter, or rapid growth through a recent galaxy collision or collisions -- future observations may tell.  The light we see today from UGC 12591 left about 400 million years ago, when trees were first developing on Earth.    Open Science: Browse 1,400+ codes in the Astrophysics Source Code Library
Dust, Gas, and Stars in the Orion Nebula (2017-03-08)

The Great Nebula in Orion, an immense, nearby starbirth region, is probably the most famous of all astronomical nebulas.  Here, filaments of dark dust and glowing gas surround hot young stars at the edge of an immense interstellar molecular cloud only 1500 light-years away.  In the featured deep image shown in assigned colors, part of the nebula's center is shown as taken by the Hubble Space Telescope. The Great Nebula in Orion can be found with the unaided eye near the easily identifiable belt of three stars in the popular constellation Orion.  In addition to housing a bright open cluster of stars known as the Trapezium, the Orion Nebula contains many stellar nurseries.   These nurseries contain much hydrogen gas, hot young stars, proplyds, and stellar jets spewing material at high speeds.  Also known as M42 and M43, the Orion Nebula spans about 40 light years and is located in the same spiral arm of our Galaxy as the Sun.

Image credit: Jes�s M.Vargas & Maritxu Poyal
Centaurus A (2017-03-09)

Only 11 million light-years away, Centaurus A is the closest active galaxy to planet Earth. Spanning over 60,000 light-years, the peculiar elliptical galaxy also known as NGC 5128, is featured in this sharp telescopic view. Centaurus A is apparently the result of a collision of two otherwise normal galaxies resulting in a fantastic jumble of star clusters and imposing dark dust lanes. Near the galaxy's center, left over cosmic debris is steadily being consumed by a central black hole with a billion times the mass of the Sun. As in other active galaxies, that process likely generates the radio, X-ray, and gamma-ray energy radiated by Centaurus A. The remarkably deep, visible light image offers further evidence of the ensuing cosmic violence in the faint shells and extended features surrounding the active galaxy.

Image credit: Fabian Neyer