juliensimon/nasa-apod huggingface dataset:
A Sunset Night Sky over the Grand Canyon (2020-02-04)

Seeing mountain peaks glow red from inside the Grand Canyon was one of the most incredible sunset experiences of this amateur photographer's life. They appeared even more incredible later, when digitally combined with an exposure of the night sky -- taken by the same camera and from the same location -- an hour later.  The two images were taken last August from the 220 Mile Canyon campsite on the Colorado River, Arizona, USA. The peaks glow red because they were lit by an unusually red sunset.  Later, high above, the band of the Milky Way Galaxy angled dramatically down, filled with stars, nebula, and dark clouds of dust. To the Milky Way's left is the planet Saturn, while to the right is the brighter Jupiter.  Although Jupiter and Saturn are now hard to see, Venus will be visible and quite bright to the west in clear skies, just after sunset, for the next two months.    Astrophotography with Your Computer: NASA's Astrophoto Challenges

Image credit: Robert Q. Fugate
Lunar Eclipse Perspectives (2020-02-05)

Do we all see the same Moon?  Yes, but we all see it differently. One difference is the apparent location of the Moon against background stars -- an effect known as parallax. We humans use the parallax between our eyes to judge depth. To see lunar parallax, though, we need eyes placed at a much greater separations -- hundreds to thousands of kilometers apart.  Another difference is that observers around the Earth all see a slightly different face of our spherical Moon -- an effect known as libration. The featured image is a composite of many views across the Earth, as submitted to APOD, of the total lunar eclipse of 2019 January 21.  These images are projected against the same background stars to illustrate both effects.  The accurate superposition of these images was made possible by a serendipitous meteorite impact on the Moon during the lunar eclipse, labeled here L1-21J -- guaranteeing that these submitted images were all taken within a split second.  With the simultaneous observations made by independent amateur astronomers across the globe, a group of astronomers were able to use their citizen-science images to narrow down the location, orbit, and energy of this rare event.
Southern Moonscape (2020-02-06)

The Moon's south pole is near the top of this detailed telescopic view. Looking across the rugged southern lunar highlands it was captured from southern California, planet Earth. At the Moon's third quarter phase the lunar terminator, the sunset shadow line, is approaching from the left. The scene's foreshortened perspective heightens the impression of a dense field of craters and makes the craters themselves appear more oval shaped close to the lunar limb. Below and left of center is sharp-walled crater Tycho, 85 kilometers in diameter. Young Tycho's central peak is still in sunlight, but casts a long shadow across the crater floor. The large prominent crater to the south (above) Tycho is Clavius. Nearly 231 kilometers in diameter its walls and floor are pocked with smaller, more recent, overlaying impact craters. Mountains visible along the lunar limb at the top can rise about 6 kilometers or so above the surrounding terrain.

Image credit: Tom Glenn
NGC 7331 Close Up (2020-02-07)

Big, beautiful spiral galaxy NGC 7331 is often touted as an analog to our own Milky Way. About 50 million light-years distant in the northern constellation Pegasus, NGC 7331 was recognized early on as a spiral nebula and is actually one of the brighter galaxies not included in Charles Messier's famous 18th century catalog. Since the galaxy's disk is inclined to our line-of-sight, long telescopic exposures often result in an image that evokes a strong sense of depth. This Hubble Space Telescope close-up spans some 40,000 light-years. The galaxy's magnificent spiral arms feature dark obscuring dust lanes, bright bluish clusters of massive young stars, and the telltale reddish glow of active star forming regions. The bright yellowish central regions harbor populations of older, cooler stars. Like the Milky Way, a supermassive black hole lies at the core of spiral galaxy NGC 7331.
Cosmic Clouds in the Unicorn (2020-02-08)

Interstellar clouds of hydrogen gas and dust abound in this gorgeous skyscape. The 3 degree wide field of view stretches through the faint but fanciful constellation Monoceros, the Unicorn. A star forming region cataloged as NGC 2264 is centered, a complex jumble of cosmic gas, dust and stars about 2,700 light-years distant. It mixes reddish emission nebulae excited by energetic light from newborn stars with dark dust clouds. Where the otherwise obscuring dust clouds lie close to hot, young stars they also reflect starlight, forming blue reflection nebulae. A few light-years across, a simple sculpted shape known as the Cone Nebula is near center. Outlined by the red glow of hydrogen gas, the cone points toward the left and bright, blue-white S Monocerotis. Itself a multiple system of massive, hot stars S Mon is adjacent to bluish reflection nebulae and the convoluted Fox Fur nebula. Expansive dark markings on the sky are silhouetted by a larger region of fainter emission with yellowish open star cluster Trumpler 5 near the top of the frame. The curious compact cometary shape right of center is known as Hubble's Variable Nebula.

Image credit: Bray Falls
To Fly Free in Space (2020-02-09)

What would it be like to fly free in space?  At about 100 meters from the cargo bay of the space shuttle Challenger, Bruce McCandless II was living the dream -- floating farther out than anyone had ever been before.  Guided by a Manned Maneuvering Unit (MMU), astronaut McCandless, pictured, was floating free in space. McCandless and fellow NASA astronaut Robert Stewart were the first to experience such an "untethered space walk" during Space Shuttle mission 41-B in 1984.  The MMU worked by shooting jets of nitrogen and was used to help deploy and retrieve satellites.  With a mass over 140 kilograms, an MMU is heavy on Earth, but, like everything, is weightless when drifting in orbit. The MMU was later replaced with the SAFER backpack propulsion unit.
Solar Eclipse over the UAE (2020-02-10)

What's happening behind that camel? A partial eclipse of the Sun. About six and a half weeks ago, the Moon passed completely in front of the Sun as seen from a narrow band on the Earth. Despite (surely) many camels being located in this narrow band, only one found itself stationed between this camera, the distant Moon, and the even more distant Sun. To create this impressive superposition, though, took a well-planned trip to the United Arab Emirates, careful alignments, and accurate timings on the day of the eclipse.  Although the resulting featured image shows a partially eclipsed Sun rising, the Moon went on to appear completely engulfed by the Sun in an annular eclipse known as a ring of fire.  Forward scattering of sunlight, dominated by quantum mechanical diffraction, gives the camel hair and rope fray an unusual glow.  The next solar eclipse is also an annular eclipse and will occur this coming June.   News: Solar Orbiter Launched

Image credit: Joshua Cripps
Launch of the Solar Orbiter (2020-02-11)

How does weather on the Sun affect humanity? To help find out, the European Space Agency (ESA) and NASA have just launched the Solar Orbiter.  This Sun-circling robotic spaceship will monitor the Sun's changing light, solar wind, and magnetic field not only from the usual perspective of Earth but also from above and below the Sun.  Pictured, a long duration exposure of the launch of the Solar Orbiter shows the graceful arc of the bright engines of United Launch Alliance's Atlas V rocket as they lifted the satellite off the Earth.  Over the next few years, the Solar Orbiter will use the gravity of Earth and Venus to veer out of the plane of the planets and closer to the Sun than Mercury.  Violent weather on the Sun, including solar flares and coronal mass ejections, has shown the ability to interfere with power grids on the Earth and communications satellites in Earth orbit.  The Solar Orbiter is expected to coordinate observations with the also Sun-orbiting Parker Solar Probe launched in 2018.   Solar Orbiter to Space: Watch the Launch

Image credit: Derek Demeter
Star Trails of the North and South (2020-02-12)

What divides the north from the south? It all has to do with the spin of the Earth. On Earth's surface, the equator is the dividing line, but on Earth's sky, the dividing line is the Celestial Equator -- the equator's projection onto the sky.  You likely can't see the Earth's equator around you, but anyone with a clear night sky can find the Celestial Equator by watching stars move.  Just locate the dividing line between stars that arc north and stars that arc south.  Were you on Earth's equator, the Celestial Equator would go straight up and down.  In general, the angle between the Celestial Equator and the vertical is your latitude.  The featured image combines 325 photos taken every 30 seconds over 162 minutes. Taken soon after sunset earlier this month, moonlight illuminates a snowy and desolate scene in northwest Iran. The bright streak behind the lone tree is the planet Venus setting.  Almost Hyperspace: Random APOD Generator

Image credit: Saeid Parchini
Spitzer's Trifid (2020-02-13)

The Trifid Nebula, also known as Messier 20, is easy to find with a small telescope. About 30 light-years across and 5,500 light-years distant it's a popular stop for cosmic tourists in the nebula rich constellation Sagittarius. As its name suggests, visible light pictures show the nebula divided into three parts by dark, obscuring dust lanes. But this penetrating infrared image reveals the Trifid's filaments of glowing dust clouds and newborn stars. The spectacular false-color view is courtesy of the Spitzer Space Telescope. Astronomers have used the infrared image data to count newborn and embryonic stars which otherwise can lie hidden in the natal dust and gas clouds of this intriguing stellar nursery. Launched in 2003, Spitzer explored the infrared Universe from an Earth-trailing solar orbit until its science operations were brought to a close earlier this year, on January 30.
The Pale Blue Dot (2020-02-14)

On Valentine's Day in 1990, cruising four billion miles from the Sun, the Voyager 1 spacecraft looked back one last time to make the first ever Solar System family portrait. The portrait consists of the Sun and six planets in a 60 frame mosaic made from a vantage point 32 degrees above the ecliptic plane. Planet Earth was captured within a single pixel in this single frame. It's the pale blue dot within the sunbeam just right of center in this reprocessed version of the now famous view from Voyager. Astronomer Carl Sagan originated the idea of using Voyager's camera to look back toward home from a distant perspective. Thirty years later, on this Valentine's day, look again at the pale blue dot.
Carina Nebula Close Up (2020-02-15)

A jewel of the southern sky, the Great Carina Nebula, also known as NGC 3372, spans over 300 light-years, one of our galaxy's largest star forming regions. Like the smaller, more northerly Great Orion Nebula, the Carina Nebula is easily visible to the unaided eye, though at a distance of 7,500 light-years it is some 5 times farther away. This gorgeous telescopic close-up reveals remarkable details of the region's central glowing filaments of interstellar gas and obscuring cosmic dust clouds in a field of view nearly 20 light-years across. The Carina Nebula is home to young, extremely massive stars, including the still enigmatic and violently variable Eta Carinae, a star system with well over 100 times the mass of the Sun. In the processed composite of space and ground-based image data a dusty, two-lobed Homunculus Nebula appears to surround Eta Carinae itself just below and left of center. While Eta Carinae is likely on the verge of a supernova explosion, X-ray images indicate that the Great Carina Nebula has been a veritable supernova factory.
NGC 2392: Double-Shelled Planetary Nebula (2020-02-16)

To some, this huge nebula resembles a person's head surrounded by a parka hood.  In 1787, astronomer William Herschel discovered this unusual planetary nebula:  NGC 2392.  More recently, the Hubble Space Telescope imaged the nebula in visible light,  The featured image  of the nebula shows gas clouds so complex they are not fully understood.  NGC 2392 is a double-shelled planetary nebula, with the more distant gas having composed the outer layers of a Sun-like star only 10,000 years ago.  The outer shell contains unusual light-year long orange filaments. The inner filaments visible are being ejected by strong wind of particles from the central star.  The NGC 2392 Nebula spans about 1/3 of a light year and lies in our Milky Way Galaxy, about 3,000 light years distant, toward the constellation of the Twins (Gemini).
The Changing Surface of Fading Betelgeuse (2020-02-17)

Besides fading, is Betelgeuse changing its appearance? Yes. The famous red supergiant star in the familiar constellation of Orion is so large that telescopes on Earth can actually resolve its surface -- although just barely. The two featured images taken with the European Southern Observatory's Very Large Telescope show how the star's surface appeared during the beginning and end of last year.  The earlier image shows Betelgeuse having a much more uniform brightness than the later one, while the lower half of Betelgeuse became significantly dimmer than the top. Now during the first five months of 2019 amateur observations show Betelgeuse actually got slightly brighter, while in the last five months the star dimmed dramatically. Such variability is likely just normal behavior for this famously variable supergiant, but the recent dimming has rekindled discussion on how long it may be before Betelgeuse does go supernova. 	 Since Betelgeuse is about 700 light years away, its eventual supernova -- probably thousands of years in the future -- will likely be an amazing night-sky spectacle, but will not endanger life on Earth.
Orion over the Central Bohemian Highlands (2020-02-18)

Do you recognize this constellation? Setting past the Central Bohemian Highlands in the Czech Republic is Orion, one of the most identifiable star groupings on the sky and an icon familiar to humanity for over 30,000 years. Orion has looked pretty much the same during this time and should continue to look the same for many thousands of years into the future.  Prominent Orion is high in the sky at sunset this time of year, a recurring sign of (modern) winter in Earth's northern hemisphere and summer in the south. The featured picture is a composite of over thirty images taken from the same location and during the same night last month.  Below and slightly to the left of Orion's three-star belt is the Orion Nebula, while four of the bright stars surrounding the belt are, clockwise, Sirius (far left, blue), Betelgeuse (top, orange, unusually faint), Aldebaran (far right), and Rigel (below). As future weeks progress, Orion will set increasingly earlier.    Infinite Random Loop: Create an APOD Station in your classroom or Science Center.

Image credit: Vojtěch Bauer
UGC 12591: The Fastest Rotating Galaxy Known (2020-02-19)

Why does this galaxy spin so fast?  To start, even identifying which type of galaxy UGC 12591 is difficult -- featured on the lower left, 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.
Trifecta at Twilight (2020-02-20)

On February 18, as civil twilight began in northern New Mexico skies, the International Space Station, a waning crescent Moon, and planet Mars for a moment shared this well-planned single field of view. From the photographer's location the sky had just begun to grow light, but the space station orbiting 400 kilometers above the Earth was already bathed in the morning sunlight. At 6:25am local time it took about a second to cross in front of the lunar disk moving right to left in the composited successive frames. At the time, Mars itself had already emerged from behind the Moon following its much anticipated lunar occultation. The yellowish glow of the Red Planet is still in the frame at the upper right, beyond the Moon's dark edge.

Image credit: Paul Schmit
LDN 1622: Dark Nebula in Orion (2020-02-21)

The silhouette of an intriguing dark nebula inhabits this cosmic scene. Lynds' Dark Nebula (LDN) 1622 appears against a faint background of glowing hydrogen gas only visible in long telescopic exposures of the region. In contrast, the brighter reflection nebula vdB 62 is more easily seen, just above and right of center. LDN 1622 lies near the plane of our Milky Way Galaxy, close on the sky to Barnard's Loop, a large cloud surrounding the rich complex of emission nebulae found in the Belt and Sword of Orion. With swept-back outlines, the obscuring dust of LDN 1622 is thought to lie at a similar distance, perhaps 1,500 light-years away. At that distance, this 1 degree wide field of view would span about 30 light-years. Young stars do lie hidden within the dark expanse and have been revealed in Spitzer Space telescope infrared images. Still, the foreboding visual appearance of LDN 1622 inspires its popular name, the Boogeyman Nebula.

Image credit: Min Xie
Central Centaurus A (2020-02-22)

A mere 11 million light-years away, Centaurus A is the closest active galaxy to planet Earth. Also known as NGC 5128, the peculiar elliptical galaxy is over 60,000 light-years across. A region spanning about 8,500 light-years, including the galaxy's center (upper left), is framed in this sharp Hubble Space telescope close-up. Centaurus A is apparently the result of a collision of two otherwise normal galaxies resulting in a violent jumble of star forming regions, massive 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 about 60 million 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.
Illustris Simulation of the Universe (2020-02-23)

How did we get here? Click play, sit back, and watch.  A computer simulation of the evolution of the universe provides insight into how galaxies formed and perspectives into humanity's place in the universe.  The Illustris project exhausted 20 million CPU hours in 2014 following 12 billion resolution elements spanning a cube 35 million light years on a side as it evolved over 13 billion years. The simulation tracks matter into the formation of a wide variety of galaxy types. As the virtual universe evolves, some of the matter expanding with the universe soon gravitationally condenses to form filaments, galaxies, and clusters of galaxies. The featured video takes the perspective of a virtual camera circling part of this changing universe, first showing the evolution of dark matter, then hydrogen gas coded by temperature (0:45), then heavy elements such as helium and carbon (1:30), and then back to dark matter (2:07). On the lower left the time since the Big Bang is listed, while on the lower right the type of matter being shown is listed.  Explosions (0:50) depict galaxy-center supermassive black holes expelling bubbles of hot gas. Interesting discrepancies between Illustris and the real universe have been studied, including why the simulation produced an overabundance of old stars.
Moon Corona, Halo, and Arcs over Manitoba (2020-02-24)

Yes, but could you get to work on time if the Moon looked like this? As the photographer was preparing to drive to work, refraction, reflection, and even diffraction of moonlight from millions of falling ice crystals turned the familiar icon of our Moon into a menagerie of other-worldly halos and arcs. The featured scene was captured with three combined exposures two weeks ago on a cold winter morning in Manitoba, Canada. The colorful rings are a corona caused by quantum diffraction by small drops of water or ice near the direction of the Moon. Outside of that, a 22-degree halo was created by moonlight refracting through six-sided cylindrical ice crystals. To the sides are moon dogs, caused by light refracting through thin, flat, six-sided ice platelets as they flittered toward the ground.  Visible at the top and bottom of the 22-degree halo are upper and lower tangent arcs, created by moonlight refracting through nearly horizontal hexagonal ice cylinders. A few minutes later, from a field just off the road to work, the halo and arcs had disappeared, the sky had returned to normal -- with the exception of a single faint moon dog.

Image credit: Brent Mckean
Jupiter's Magnetic Field from Juno (2020-02-25)

How similar is Jupiter's magnetic field to Earth's? NASA's robotic Juno spacecraft has found that Jupiter's magnetic field is surprisingly complex, so that the Jovian world does not have single magnetic poles like our Earth.  A snapshot of Jupiter's magnetic field at one moment in time, as animated from Juno data, appears in the featured video. Red and blue colors depict cloud-top regions of strong positive (south) and negative (north) magnetic fields, respectively. Surrounding the planet are imagined magnetic field lines. The first sequence of the animated video starts off by showing what appears to be a relatively normal dipole field, but soon a magnetic region now known as the Great Blue Spot rotates into view, which is not directly aligned with Jupiter's rotation poles.  Further, in the second sequence, the illustrative animation takes us over one of Jupiter's spin poles where red magnetic hotspots are revealed to be extended and sometimes even annular.  A better understanding of Jupiter's magnetic field may give clues toward a better understanding of Earth's enigmatic planetary magnetism.
NGTS-10b: Discovery of a Doomed Planet (2020-02-26)

This hot jupiter is doomed.  Hot jupiters are giant planets like Jupiter that orbit much closer to their parent stars than Mercury does to our Sun.  But some hot jupiters are more extreme than others.  NGTS-10b, illustrated generically, is the closest and fastest-orbiting giant planet yet discovered, circling its home star in only 18 hours.  NGTS-10b is a little larger than Jupiter, but it orbits less than two times the diameter of its parent star away from the star’s surface.  When a planet orbits this close, it is expected to spiral inward, pulled down by tidal forces to be eventually ripped apart by the star’s gravity.  NGTS-10b, discovered by researchers at the University of Warwick, is named after the Next Generation Transit Survey, which detected the imperiled planet when it passed in front of its star, blocking some of the light.  Although the violent demise of NGTS-10b will happen eventually, we don't yet know when.