juliensimon/nasa-apod huggingface dataset:
Europa and Jupiter from Voyager 1 (2020-06-28)

What are those spots on Jupiter? Largest and furthest, just right of center, is the Great Red Spot -- a huge storm system that has been raging on Jupiter possibly since Giovanni Cassini's likely notation of it 355 years ago.  It is not yet known why this Great Spot is red. The spot toward the lower left is one of Jupiter's largest moons: Europa. Images from Voyager in 1979 bolster the modern hypothesis that Europa has an underground ocean and is therefore a good place to look for extraterrestrial life. But what about the dark spot on the upper right? That is a shadow of another of Jupiter's large moons: Io. Voyager 1 discovered Io to be so volcanic that no impact craters could be found.  Sixteen frames from Voyager 1's flyby of Jupiter in 1979 were recently reprocessed and merged to create the featured image.  About 43 years ago, Voyager 1 launched from Earth and started one of the greatest explorations of the Solar System ever.    Free Download: Voyager Posters
Dark Sky Reflections (2020-06-29)

When the lake calmed down, many wonders of the land and sky appeared twice. Perhaps the most dramatic from the dark sky was the central band of our Milky Way Galaxy, visible as a diagonal band. Toward the right were both the Small (SMC) and Large (LMC) Magellanic Clouds, satellite galaxies of our Milky Way. Faint multicolored bands of airglow fanned across the night. Numerous bright stars were visible including Antares, while the bright planet Jupiter appears just above the image center. The featured image is a composite of exposures all taken from the same camera and from the same location within 30 minutes in mid-May from the shore of Lake Bonney Riverland in South Australia. Dead trees that extend from the lake were captured not only in silhouette, but reflection, while lights from the small town of Barmera were visible across the lake. In July, Jupiter and Saturn will rise toward the east just as the Sun sets in the west.

Image credit: Will Godward
Bright Planetary Nebula NGC 7027 from Hubble (2020-06-30)

What created this unusual planetary nebula? NGC 7027 is one of the smallest, brightest, and most unusually shaped planetary nebulas known. Given its expansion rate, NGC 7027 first started expanding, as visible from Earth, about 600 years ago.  For much of its history, the planetary nebula has been expelling shells, as seen in blue in the featured image.  In modern times, though, for reasons unknown, it began ejecting gas and dust (seen in red) in specific directions that created a new pattern that seems to have four corners. These shells and patterns have been mapped in impressive detail by recent images from the Wide Field Camera 3 onboard the Hubble Space Telescope.  What lies at the nebula's center is unknown, with one hypothesis holding it to be a close binary star system where one star sheds gas onto an erratic disk orbiting the other star. NGC 7027, about 3,000 light years away, was first discovered in 1878 and can be seen with a standard backyard telescope toward the constellation of the Swan (Cygnus).
Our Rotating Earth (2020-07-01)

Has your world ever turned upside-down?  It would happen every day if you stay fixed to the stars.  Most time-lapse videos of the night sky show the stars and sky moving above a steady Earth.  Here, however, the camera has been forced to rotate so that the stars remain fixed, and the Earth rotates around them.  The movie, with each hour is compressed to a second, dramatically demonstrates the daily rotation of the Earth, called diurnal motion. The video begins by showing an open field in Namibia, Africa, on a clear day, last year.  Shadows shift as the Earth turns, the shadow of the Earth rises into the sky, the Belt of Venus momentarily appears, and then day turns into night. The majestic band of our Milky Way Galaxy stretches across the night sky, while sunlight-reflecting, Earth-orbiting satellites zoom by.  In the night sky, you can even spot the Large and Small Magellanic Clouds.  The video shows a sky visible from Earth's Southern Hemisphere, but a similar video could be made for every middle latitude on our blue planet.   Almost Hyperspace: Random APOD Generator

Image credit: Bartosz
Wojczyński
The Galaxy, the Planet, and the Apple Tree (2020-07-02)

The Old Astronomer's Milky Way arcs through this peaceful northern sky. Against faint, diffuse starlight you can follow dark rifts of interstellar dust clouds stretching from the galaxy's core. They lead toward bright star Antares at the right, almost due south above the horizon. The brightest beacon in the twilight is Jupiter, though. From the camera's perspective it seems to hang from the limb of a tree framing the foreground, an apple tree of course. The serene maritime nightscape was recorded in tracked and untracked exposures on June 16 from Dover, Nova Scotia, planet Earth.

Image credit: Kristine Richer
Lynds Dark Nebula 1251 (2020-07-03)

Stars are forming in Lynds Dark Nebula (LDN) 1251. About 1,000 light-years away and drifting above the plane of our Milky Way galaxy, the dusty molecular cloud is part of a complex of dark nebulae mapped toward the Cepheus flare region. Across the spectrum, astronomical explorations of the obscuring interstellar clouds reveal energetic shocks and outflows associated with newborn stars, including the telltale reddish glow from scattered Herbig-Haro objects seen in this sharp image. Distant background galaxies also lurk on the scene, buried behind the dusty expanse. This alluring view imaged with a backyard telescope and broadband filters spans about two full moons on the sky, or 17 light-years at the estimated distance of LDN 1251.

Image credit: Ara Jerahian
Meeting in the Mesosphere (2020-07-04)

A sensitive video camera on a summit of the Vosges mountains in France captured these surprising fireworks above a distant horizon on June 26. Generated over intense thunderstorms, this one about 260 kilometers away, the brief and mysterious flashes have come to be known as red sprites. The transient luminous events are caused by electrical breakdown at altitudes of 50 to 100 kilometers. That puts them in the mesophere, the coldest layer of planet Earth's atmosphere. The glow beneath the sprites is from more familiar lighting though, below the storm clouds. But on the right, the video frames have captured another summertime apparition from the mesophere. The silvery veins of light are polar mesospheric clouds. Also known as noctilucent or night shining clouds, the icy clouds still reflect the sunlight when the Sun is below the horizon.

Image credit: Stephane Vetter
Saturn's Northern Hexagon (2020-07-05)

Why would clouds form a hexagon on Saturn? Nobody is sure.   Originally discovered during the Voyager flybys of Saturn in the 1980s, nobody has ever seen anything like it anywhere else in the Solar System.  Acquiring its first sunlit views of far northern Saturn in late 2012, the Cassini spacecraft's wide-angle camera recorded this stunning, false-color image of the ringed planet's north pole. The composite of near-infrared image data results in red hues for low clouds and green for high ones, giving the Saturnian cloudscape a vivid appearance. This and similar images show the stability of the hexagon even 20+ years after Voyager.  Movies of Saturn's North Pole show the cloud structure maintaining its hexagonal structure while rotating.  Unlike individual clouds appearing like a hexagon on Earth, the Saturn cloud pattern appears to have six well defined sides of nearly equal length. Four Earths could fit inside the hexagon. Beyond the cloud tops at the upper right, arcs of the planet's eye-catching rings appear bright blue.
M43: Dust, Gas, and Stars in the Orion Nebula (2020-07-06)

Unspeakable beauty and unimaginable bedlam can be found together in the Orion Nebula Arguably the most famous of all astronomy nebulas, the Great Nebula in Orion is an immense interstellar molecular cloud only 1500 light-years away.  In the featured deep image shown in assigned colors, the part of the nebula's center known as M43 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.  The entire Orion Nebula, including both M42 and M43 spans about 40 light years and is located in the same spiral arm of our Galaxy as the Sun.

Image credit: Bryan Goff
Comet NEOWISE over Lebanon (2020-07-07)

A comet has suddenly become visible to the unaided eye.  Comet C/2020 F3 (NEOWISE) was discovered in late March and brightened as it reached its closest approach to the Sun, inside the orbit of Mercury, late last week. The interplanetary iceberg survived solar heating, so far, and is now becoming closer to the Earth as it starts its long trek back to the outer Solar System. As Comet NEOWISE became one of the few naked-eye comets of the 21st Century, word spread quickly, and the comet has already been photographed behind many famous sites and cities around the globe. Featured, Comet NEOWISE was captured over Lebanon two days ago just before sunrise. The future brightness of Comet NEOWISE remains somewhat uncertain but the comet will likely continue to be findable not only in the early morning sky, but also next week in the early evening sky.    Comet NEOWISE from Around the Globe: Notable Images Submitted to APOD

Image credit: Maroun Habib (Moophz)
Mercury's Sodium Tail (2020-07-08)

What is that fuzzy streak extending from Mercury? Long exposures of our Solar System's innermost planet may reveal something unexpected: a tail. Mercury's thin atmosphere contains small amounts of sodium that glow when excited by light from the Sun. Sunlight also liberates these molecules from Mercury's surface and pushes them away. The yellow glow from sodium, in particular, is relatively bright.  Pictured, Mercury and its sodium tail are visible in a deep image taken in late May from Italy through a filter that primarily transmits yellow light emitted by sodium. First predicted in the 1980s, Mercury's tail was first discovered in 2001. Many tail details were revealed in multiple observations by NASA's robotic MESSENGER spacecraft that orbited Mercury between 2011 and 2015.  Tails are usually associated with comets.  The tails of Comet NEOWISE are currently visible with the unaided eye in the morning sky.    Comet NEOWISE from Around the Globe: Notable Images Submitted to APOD

Image credit: Andrea Alessandrini
Noctilucent Clouds and Comet NEOWISE (2020-07-09)

These silvery blue waves washing over a tree-lined horizon in the eastern French Alps are noctilucent clouds. From high in planet Earth's mesosphere, they reflect sunlight in this predawn skyscape taken on July 8. This summer, the night-shining clouds are not new to the northern high-latitudes. Comet NEOWISE is though. Also known as C/2020 F3, the comet was discovered in March by the Earth-orbiting Near Earth Object Wide-field Infrared Survey Explorer (NEOWISE) satellite. It's now emerging in morning twilight only just visible to the unaided eye from a clear location above the northeastern horizon.

Image credit: Emmanuel Paoly
Comet NEOWISE from the ISS (2020-07-10)

Rounding the Sun on July 3rd and currently headed for the outer Solar System, Comet NEOWISE (C/2020 F3) has been growing brighter in the predawn skies of planet Earth. From low Earth orbit it also rises before the Sun, captured above the approaching glow along the eastern horizon in this snapshot from the International Space Station on July 5. Venus, now Earth's morning star is the brilliant celestial beacon on the right in the field of view. Above Venus you can spot the sister stars of the more compact Pleiades cluster. Earthbound skygazers can spot this comet with the unaided eye, but should look for awesome views with binoculars.   Comet NEOWISE from Earth's Surface: Notable Images Submitted to APOD
The Tails of Comet NEOWISE (2020-07-11)

Comet NEOWISE (C/2020 F3) is now sweeping through northern skies. Its developing tails stretch some six degrees across this telescopic field of view, recorded from Brno, Czech Republic before daybreak on July 10. Pushed out by the pressure of sunlight itself, the comet's broad, yellowish dust tail is easiest to see. But the image also captures a fainter, more bluish tail too, separate from the reflective comet dust. The fainter tail is an ion tail, formed as ions from the cometary coma are dragged outward by magnetic fields in the solar wind and fluoresce in the sunlight. In this sharp portrait of our new visitor from the outer Solar System, the tails of comet NEOWISE are reminiscent of the even brighter tails of Hale Bopp, the Great Comet of 1997.   Comet NEOWISE from Around the Globe: Notable Images Submitted to APOD

Image credit: Miloslav Druckmuller
Comet CG Creates Its Dust Tail (2020-07-12)

Where do comet tails come from?  There are no obvious places on the nuclei of comets from which the jets that create comet tails emanate.  One of the best images of emerging jets is shown in the featured picture, taken in 2015 by ESA's robotic Rosetta spacecraft that orbited Comet 67P/Churyumov-Gerasimenko (Comet CG) from 2014 to 2016.  The picture shows plumes of gas and dust escaping numerous places from Comet CG's nucleus as it neared the Sun and heated up.  The comet has two prominent lobes, the larger one spanning about 4 kilometers, and a smaller 2.5-kilometer lobe connected by a narrow neck. Analyses indicate that evaporation must be taking place well inside the comet's surface to create the jets of dust and ice that we see emitted through the surface.  Comet CG (also known as Comet 67P) loses in jets about a meter of radius during each of its 6.44-year orbits around the Sun, a rate at which will completely destroy the comet in only thousands of years. In 2016, Rosetta's mission ended with a controlled impact onto Comet CG's surface.   Comet NEOWISE from Around the Globe: Notable Images Submitted to APOD
Comet NEOWISE Rising over the Adriatic Sea (2020-07-13)

This sight was worth getting out of bed early.  Comet C/2020 F3 (NEOWISE) has been rising before dawn during the past week to the delight of northern sky enthusiasts awake that early. Up before sunrise, the featured photographer was able to capture in dramatic fashion one of the few comets visible to the unaided eye this century, an inner-Solar System intruder that might become known as the Great Comet of 2020.  The resulting video details Comet NEOWISE from Italy rising over the Adriatic Sea. The time-lapse video combines over 240 images taken over 30 minutes.  The comet is seen rising through a foreground of bright and undulating noctilucent clouds, and before a background of distant stars.  Comet NEOWISE has remained unexpectedly bright, so far, with its ion and dust tails found to emanate from a nucleus spanning about five kilometers across.  Fortunately, starting tonight, northern observers with a clear and dark northwestern horizon should be able to see the sun-reflecting interplanetary snowball just after sunset.   Notable Images of Comet NEOWISE Submitted to APOD:  || July 12  || July 11  || July 10 & earlier ||

Image credit: Paolo Girotti
Comet NEOWISE over Stonehenge (2020-07-14)

Have you ever seen a comet? Tonight -- and likely the next few nights -- should be a good chance. Go outside just at sunset and look to your northwest.  The lower your horizon, the better.  Binoculars may help, but if your sky is cloudless and dark, all you should need is your unaided eyes and patience. As the Sun sets, the sky will darken, and there will be an unusual faint streak pointing diagonally near the horizon. That is Comet NEOWISE. It is a 5-kilometer-wide evaporating dirty iceberg visiting from -- and returning to -- the outer Solar System. As the Earth turns, the comet will soon set, so you might want to take a picture. In the featured image, Comet C/2020 F3 (NEOWISE) was captured two mornings ago rising over Stonehenge in the UK.  Discovered with the NASA satellite NEOWISE toward the end of March, Comet NEOWISE has surprised many by surviving its closest approach to the Sun, brightening dramatically, and developing impressive (blue) ion and (white) dust tails.    Notable Images of Comet NEOWISE Submitted to APOD:  || July 13  || July 12  || July 11  || July 10 & earlier ||

Image credit: Declan Deval
Comet NEOWISE over the Swiss Alps (2020-07-15)

Comet NEOWISE has been wowing photographers around much of the world during dawn and dusk, at the margins of day and night.  For the most northern residents of planet Earth, however, the comet circles the North Star and never sets. The night part of this circular arc is apparent in the featured composite of images assembled from a webcam located at a ski resort in the Swiss Alps.  Images were selected at 30-minute intervals throughout the night from July 12th -13th. Comet NEOWISE (C/2020 F3) will continue to become more accessible to northern hemisphere observers as its motion places it higher in the sky each evening after sunset over the next few weeks, as it begins its outbound journey.  As with all comets, departure from the inner Solar System comes with inevitable fading.  Binoculars are the best way to find and observe the comet visually.    Notable Images of Comet NEOWISE Submitted to APOD:  || July 14  || July 13  || July 12  || July 11  || July 10 & earlier ||

Image credit: Philipp Salzgeber, 
foto-webcam.eu;
Text: 
Adam Block
The Long Tails of Comet NEOWISE (2020-07-16)

This Comet NEOWISE (C/2020 F3) now sweeps through our fair planet's northern skies. Its long tails stretch across this deep skyview from Suchy Vrch, Czech Republic. Recorded on the night of July 13/14, the composite of untracked foreground and tracked and filtered sky exposures teases out details in the comet's tail not visible to the unaided eye. Faint structures extend to the top of the frame, over 20 degrees from the comet's bright coma. Pushed out by the pressure of sunlight itself, the broad curve of the comet's yellowish dust tail is easy to see by eye. But the fainter, more bluish tail is separate from the reflective comet dust. The fainter tail is an ion tail, formed as ions from the cometary coma are dragged outward by magnetic fields in the solar wind and fluoresce in the sunlight. Outbound NEOWISE is climbing higher in northern evening skies, coming closest to Earth on July 23rd.  Comet NEOWISE Images: July 15 | July 14 | July 13 | July 12 | July 11 | July 10 & earlier

Image credit: Petr Horalek
NEOWISE of the North (2020-07-17)

After local midnight on July 14 comet NEOWISE was still above the horizon for Goldenrod, Alberta, Canada, just north of Calgary, planet Earth. In this snapshot it makes for an awesome night with dancing displays of the northern lights. The long-tailed comet and auroral displays are beautiful apparitions in the north these days. Both show the influence of spaceweather and the wind from the Sun. Skygazers have widely welcomed the visitor from the Oort cloud, though C/2020 F3 (NEOWISE) is in an orbit that is now taking it out of the inner Solar System.  Comet NEOWISE Images: July 16 | July 15 | July 14 | July 13 | July 12 | July 11 | July 10 & earlier

Image credit: Bill Peters
Finding NEOWISE (2020-07-18)

If you can see the stars of the Big Dipper, you can find comet NEOWISE in your evening sky tonight. After sunset look for the naked-eye comet below the bowl of the famous celestial kitchen utensil of the north and above your northwestern horizon. You're looking for a fuzzy 'star' with a tail, though probably not so long a tail as in this clear sky snapshot taken from Los Padres National Forest in California on the evening of July 16. Recent photographs of C/2020 F3 (NEOWISE) often show this comet's broad dust tail and fainter but separate ion tail extending farther than the eye can follow. Skygazers around the world have been delighted to find NEOWISE, surprise visitor from the outer Solar System.  Comet NEOWISE Images: July 17 | July 16 | July 15 | July 14 | July 13 | July 12 | July 11 | July 10 & earlier

Image credit: Tom Masterson
Rotating Moon from LRO (2020-07-19)

No one, presently, sees the Moon rotate like this. That's because the Earth's moon is tidally locked to the Earth, showing us only one side.  Given modern digital technology, however, combined with many detailed images returned by the Lunar Reconnaissance Orbiter (LRO), a high resolution virtual Moon rotation movie has been composed. The featured time-lapse video starts with the standard Earth view of the Moon. Quickly, though, Mare Orientale, a large crater with a dark center that is difficult to see from the Earth, rotates into view just below the equator.  From an entire lunar month condensed into 24 seconds, the video clearly shows that the Earth side of the Moon contains an abundance of dark lunar maria, while the lunar far side is dominated by bright lunar highlands. Currently, over 19 new missions to the Moon are under active development from eight different countries, most of which have expected launch dates in the next three years.    Notable Images of Comet NEOWISE Submitted to APOD: July || 18  || 17  || 16  || 15  || 14  || 13  || 12  || 11  || 10 & earlier ||
Comet NEOWISE and Nebulae (2020-07-20)

Would you brave wild animals to photograph this sky? One astrophotographer did -- and we all get to reap the rewards.  First, thousands of stars were visible with many of the brightest impressively blue. Next, several red-glowing nebulae were discernible, including the California Nebula on the far right, and, above it, the Heart and Soul nebulae. But the real reason to brave the local wildlife was Comet NEOWISE, visible on the left.  In the featured long-duration composite taken last week, Comet NEOWISE's blue-glowing ion tail points straight up, away from the rising Sun, while the Sun-reflecting dust tail trails off toward the right.  The picture combines three exposures taken consecutively over 10 minutes from the same location near Miedzygórze, Poland.  A moonlit dirt road shows the path ahead, while the Śnieznik Mountains is visible on the horizon. Comet C/2020 F3 (NEOWISE) passes its closest to the Earth next week, after which the 5-km wide, evaporating, icy dirtball will fade as it glides back to the outer Solar System.   Notable Images of Comet NEOWISE Submitted to APOD: July || 19  || 18   || 17   || 16   || 15  || 14  || 13  || 12  || 11  || 10 & earlier ||

Image credit: Jarek Oszywa
Iron in the Butterfly Nebula (2020-07-21)

Can stars, like caterpillars, transform themselves into butterflies? No, but in the case of the Butterfly Nebula -- it sure looks like it. Though its wingspan covers over 3 light-years and its estimated surface temperature exceeds 200,000 degrees, C, the dying central star of NGC 6302, the featured planetary nebula, has become exceptionally hot, shining brightly in visible and ultraviolet light but hidden from direct view by a dense torus of dust. This sharp close-up was recorded by the Hubble Space Telescope and is reprocessed here to show off the remarkable details of the complex planetary nebula, highlighting in particular light emitted by iron, shown in red.  NGC 6302 lies about 4,000 light-years away in the arachnologically correct constellation of the Scorpion (Scorpius). Planetary nebulas evolve from outer atmospheres of stars like our Sun, but usually fade in about 20,000 years.   Great Debates in Astronomy: 2020: How will humanity first discover extraterrestrial life?