juliensimon/nasa-apod huggingface dataset:
An Annular Solar Eclipse over New Mexico (2023-09-10)

What is this person doing?  In 2012, an annular eclipse of the Sun was visible over a narrow path that crossed the northern Pacific Ocean and several western US states.  In an annular solar eclipse, the Moon is too far from the Earth to block out the entire Sun, leaving the Sun peeking out over the Moon's disk in a ring of fire.  To capture this unusual solar event, an industrious photographer drove from Arizona to New Mexico to find just the right vista. After setting up and just as the eclipsed Sun was setting over a ridge about 0.5 kilometers away, a person unknowingly walked right into the shot. Although grateful for the unexpected human element, the photographer never learned the identity of the silhouetted interloper. It appears likely that the person is holding a circular device that would enable them to get their own view of the eclipse. The shot was taken at sunset on 2012 May 20 at 7:36 pm local time from a park near Albuquerque.  Next month, on October 14, a different narrow swath across North and South America will be exposed to a different annular solar eclipse, if the sky is clear. Simultaneously, cloud-free observers almost anywhere on either continent will be able to see a partial solar eclipse.

Image credit: Colleen Pinski
Beautiful Comet Nishimura (2023-09-11)

This scene would be beautiful even without the comet. By itself, the sunrise sky is an elegant deep blue on high, with faint white stars peeking through, while near the horizon is a pleasing tan. By itself, the foreground hills of eastern Slovakia are appealingly green, with the Zadňa hura and Veľká hora hills in the distance, and with the lights of small towns along the way.  Venus, by itself on the right, appears unusually exquisite, surrounded by a colorful atmospheric corona. But what attracts the eye most is the comet. On the left, in this composite image taken just before dawn yesterday morning, is Comet Nishimura.  On recent mornings around the globe, its bright coma and long ion tail make many a morning panoramic photo unusually beautiful.  Tomorrow, C/2023 P1 (Nishimura) will pass its nearest to the Earth for about the next 434 years.

Image credit: Petr Horálek /
Institute of Physics in Opava
Galaxy Cluster Abell 370 and Beyond (2023-09-12)

Some 4 billion light-years away, massive galaxy cluster Abell 370 is captured in this sharp Hubble Space Telescope snapshot. The cluster of galaxies only appears to be dominated by two giant elliptical galaxies and infested with faint arcs. In reality, the fainter, scattered bluish arcs, along with the dramatic dragon arc below and left of center, are images of galaxies that lie far beyond Abell 370. About twice as distant, their otherwise undetected light is magnified and distorted by the cluster's enormous gravitational mass, overwhelmingly dominated by unseen dark matter. Providing a tantalizing glimpse of galaxies in the early universe, the effect is known as gravitational lensing. A consequence of warped spacetime, lensing was predicted by Einstein almost a century ago. Far beyond the spiky foreground Milky Way star at lower right, Abell 370 is seen toward the constellation Cetus, the Sea Monster. It was the last of six galaxy clusters imaged in the Frontier Fields project.
NGC 4632: Galaxy with a Hidden Polar Ring (2023-09-13)

Galaxy NGC 4632 hides a secret from optical telescopes.  It is surrounded by a ring of cool hydrogen gas orbiting at 90 degrees to its spiral disk.  Such polar ring galaxies have previously been discovered using starlight.  However, NGC 4632 is among the first in which a radio telescope survey revealed a polar ring.  The featured composite image combines this gas ring, observed with the highly sensitive ASKAP telescope, with optical data from the Subaru telescope.  Using virtual reality, astronomers separated out the gas in the main disk of the galaxy from the ring, and the subtle color gradient traces its orbital motion.  Why do polar rings exist?  They could be material pulled from one galaxy as it gravitationally interacts with a companion.  Or hydrogen gas flows along the filaments of the cosmic web and accretes into a ring around a galaxy, some of which gravitationally contracts into stars.
NGC 7331 and Beyond (2023-09-14)

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 images that evokes a strong sense of depth. The effect is further enhanced in this sharp image by galaxies that lie beyond the gorgeous island universe. The most prominent background galaxies are about one tenth the apparent size of NGC 7331 and so lie roughly ten times farther away. Their close alignment on the sky with NGC 7331 occurs just by chance. Lingering above the plane of the Milky Way, this striking visual grouping of galaxies is known to some as the Deer Lick Group.

Image credit: Ian Gorenstein
Venus, Moon, and the Smoking Mountain (2023-09-15)

Venus has returned, now appearing in planet Earth's predawn skies as a brilliant morning star. From a window seat on a flight to Mexico City, the bright celestial beacon was captured just before sunrise in this astronomical snapshot, taken on September 12. Venus, at the upper right, shared the early twilight with an old crescent Moon. Seen from this stratospheric perspective, mountain peaks and clouds appear in silhouette along a glowing eastern horizon. The dramatic, long, low cloud bank was created by ongoing venting from planet Earth's active volcano Popocatépetl.

Image credit: Luis Miguel Meade Rodríguez
Fireball over Iceland (2023-09-16)

On September 12, from a location just south of the Arctic Circle, stones of Iceland's modern Arctic Henge point skyward in this startling scene. Entertaining an intrepid group of aurora hunters during a geomagnetic storm, alluring northern lights dance across the darkened sky when a stunning fireball meteor explodes. Awestruck, the camera-equipped skygazers captured video and still images of the boreal bolide, at its peak about as bright as a full moon. Though quickly fading from view, the fireball left a lingering visible trail or persistent train. The wraith-like trail was seen for minutes wafting in the upper atmosphere at altitudes of 60 to 90 kilometers along with the auroral glow.

Image credit: Jennifer Franklin
Moon Mountains Magnified during Ring of Fire Eclipse (2023-09-17)

What are those dark streaks in this composite image of a solar eclipse? They are reversed shadows of mountains at the edge of the Moon.  The center image, captured from Xiamen, China, has the Moon's center directly in front of the Sun's center. The Moon, though, was too far from the Earth to completely block the entire Sun.  Light that streamed around the edges of the Moon is called a  ring of fire. Images at each end of the sequence show sunlight that streamed through lunar valleys.  As the Moon moved further in front of the Sun, left to right, only the higher peaks on the Moon's perimeter could block sunlight.  Therefore, the dark streaks are projected, distorted, reversed, and magnified shadows of mountains at the Moon's edge.  Bright areas are called Baily's Beads. Only people in a narrow swath across Earth's Eastern Hemisphere were able to view this full annular solar eclipse in 2020. Next month, though, a narrow swath crossing both North and South America will be exposed to the next annular solar eclipse. And next April, a total solar eclipse will be visible across North America.   Open Science: Browse 3,000+ codes in the Astrophysics Source Code Library

Image credit: Wang Letian  
(Eyes at Night)
The Red Sprite and the Tree (2023-09-18)

The sprite and tree could hardly be more different. To start, the red sprite is an unusual form of lightning, while the tree is a common plant. The sprite is far away -- high in Earth's atmosphere, while the tree is nearby -- only about a football field away.  The sprite is fast -- electrons streaming up and down at near light's speed, while the tree is slow -- wood anchored to the ground. The sprite is bright -- lighting up the sky, while the tree is dim -- shining mostly by reflected light. The sprite was fleeting -- lasting only a small fraction of a second, while the tree is durable -- living now for many years.  Both however, when captured together, appear oddly similar in this featured composite image captured early this month in France as a thunderstorm passed over mountains of the Atlantic Pyrenees.    Your Sky Surprise: What picture did APOD feature on your birthday? (post 1995)

Image credit: Maxime Villaeys
HH 211: Jets from a Forming Star (2023-09-19)

Do stars always create jets as they form? No one is sure. As a gas cloud gravitationally contracts, it forms a disk that can spin too fast to continue contracting into a protostar.  Theorists hypothesize that this spin can be reduced by expelling jets. This speculation coincides with known Herbig-Haro (HH) objects, young stellar objects seen to emit jets -- sometimes in spectacular fashion. Pictured is Herbig-Haro 211, a young star in formation recently imaged by the Webb Space Telescope (JWST) in infrared light and in great detail.  Along with the two narrow beams of particles, red shock waves can be seen as the outflows impact existing interstellar gas. The jets of HH 211 will likely change shape as they brighten and fade over the next 100,000 years, as research into the details of star formation continues.
Methane Discovered on Distant Exoplanet (2023-09-20)

Where else might life exist?  One of humanity's great outstanding questions, locating planets where extrasolar life might survive took a step forward in 2019 with the discovery of a significant amount of water vapor in the atmosphere of distant exoplanet K2-18b. The planet and its parent star, K2-18, lie about 124 light years away toward the constellation of the Lion (Leo). The exoplanet is significantly larger and more massive than our Earth, but orbits in the habitable zone of its home star. K2-18, although more red than our Sun, shines in K2-18b's sky with a brightness similar to the Sun in Earth's sky.  The 2019 discovery of atmospheric water was made in data from three space telescopes: Hubble, Spitzer, and Kepler, by noting the absorption of water-vapor colors when the planet moved in front of the star.  Now in 2023, further observations by the Webb Space Telescope in infrared light have uncovered evidence of other life-indicating molecules -- including methane.  The featured illustration imagines exoplanet K2-18b on the far right orbited by a moon (center), which together orbit a red dwarf star depicted on the lower left.
Tagging Bennu (2023-09-21)

The OSIRIS-REx spacecraft's arm reached out and touched asteroid 101955 Bennu on October 20, 2020, after a careful approach to the small, near-Earth asteroid's boulder-strewn surface. Dubbed a Touch-And-Go (TAG) sampling event, the 30 centimeter wide sampling head (TAGSAM) appears to crush some of the rocks in this close-up recorded by the spacecraft's SamCam. The image was snapped just after surface contact some 321 million kilometers from planet Earth. One second later, the spacecraft fired nitrogen gas from a bottle to blow a substantial amount of Bennu's regolith into the sampling head, collecting the loose surface material. And now, nearly three years later, on Sunday, September 24, that sample of asteroid Bennu is scheduled to arrive on planet Earth. The sample return capsule will be dropped off by the OSIRIS-Rex spacecraft as it makes a close flyby of Earth. Twenty minutes after the drop-off, the spacecraft will fire its thrusters to divert past Earth and continue on to orbit near-Earth asteroid 99942 Apophis.
Cosmos in Reflection (2023-09-22)

During the day, over 12,000 large mirrors reflect sunlight at the 100-megawatt, molten-salt, solar thermal power plant at the western edge of the Gobi desert near Dunhuang, Gansu Province, China. Individual mirror panels turn to track the sun like sunflowers. They conspire to act as a single super mirror reflecting the sunlight toward a fixed position, the power station's central tower. During the night the mirrors stand motionless though. They reflect the light of the countless distant stars, clusters and nebulae of the Milky Way and beyond. This sci-fi night skyscape was created with a camera fixed to a tripod near the edge of the giant mirror matrix on September 15. The camera's combined sequence of digital exposures captures concentric arcs of celestial star trails through the night with star trails in surreal mirrored reflection.

Image credit: Jeff Dai
Afternoon Analemma (2023-09-23)

An analemma is that figure-8 curve you get when you mark the position of the Sun at the same time each day for one year. To make this one, a 4x5 pinhole camera was set up looking north in southern New Zealand skies. The shutter was briefly opened each clear day in the afternoon at 4pm local time exposing the same photosensitized glass plate for the year spanning September 23, 2022 to September 19, 2023. On two days, the winter and summer solstices, the shutter was opened again 15 minutes after the main exposure and remained open until sunset to create the sun trails at the bottom and top of the curve. The equinox dates correspond to positions in the middle of the curve, not the crossover point. Of course, the curve itself is inverted compared to an analemma traced from the northern hemisphere. And while fall begins today at the Autumnal Equinox for the northern hemisphere, it's the Spring Equinox in the south.

Image credit: Ian Griffin
A Ring of Fire Sunrise Solar Eclipse (2023-09-24)

What's rising above the horizon behind those clouds? It's the Sun.  Most sunrises don't look like this, though, because most sunrises don't include the Moon. In the early morning of 2013 May 10, however, from Western Australia, the Moon was between the Earth and the rising Sun.  At times, it would be hard for the uninformed to understand what was happening.  In an annular eclipse, the Moon is too far from the Earth to block the entire Sun, and at most leaves a ring of fire where sunlight pours out around every edge of the Moon.  The featured time-lapse video also recorded the eclipse through the high refraction of the Earth's atmosphere just above the horizon, making the unusual rising Sun and Moon appear also flattened.  As the video continues, the Sun continues to rise, while the Sun and Moon begin to separate.  The next annular solar eclipse will occur in less than three weeks.  On Saturday, October 14, a ring of fire will be visible through clear skies from a thin swath crossing both North and South America.   Tour the Universe: Random APOD Generator
Arp 142: The Hummingbird Galaxy (2023-09-25)

What's happening to this spiral galaxy? Just a few hundred million years ago, NGC 2936, the upper of the two large galaxies shown at the bottom, was likely a normal spiral galaxy -- spinning, creating stars -- and minding its own business. But then it got too close to the massive elliptical galaxy NGC 2937, just below, and took a turn. Sometimes dubbed the Hummingbird Galaxy for its iconic shape, NGC 2936 is not only being deflected but also being distorted by the close gravitational interaction. Behind filaments of dark interstellar dust, bright blue stars form the nose of the hummingbird, while the center of the spiral appears as an eye.  Alternatively, the galaxy pair, together known as Arp 142, look to some like Porpoise or a penguin protecting an egg. The featured re-processed image showing Arp 142 in great detail was taken recently by the Hubble Space Telescope. Arp 142 lies about 300 million light years away toward the constellation of the Water Snake (Hydra). In a billion years or so the two galaxies will likely merge into one larger galaxy.
IC 4592: The Blue Horsehead Reflection Nebula (2023-09-26)

Do you see the horse's head?   What you are seeing is not the famous Horsehead nebula toward Orion, but rather a fainter nebula that only takes on a familiar form with deeper imaging.  The main part of the here-imaged molecular cloud complex is  reflection nebula IC 4592.  Reflection nebulas are made up of very fine dust that normally appears dark but can look quite blue when reflecting the visible light of energetic nearby stars.  In this case, the source of much of the reflected light is a star at the eye of the horse.  That star is part of Nu Scorpii, one of the brighter star systems toward the constellation of the Scorpion (Scorpius).   A second reflection nebula dubbed IC 4601 is visible surrounding two stars above and to the right of the image center.

Image credit: Antoine & Dalia Grelin
STEVE and Milky Way Cross over Rural Road (2023-09-27)

Not every road ends in a STEVE. A week ago, a sky enthusiast's journey began with a goal: to photograph an aurora over Lake Huron. Driving through rural Ontario, Canada, the forecasted sky show started unexpectedly early, causing the photographer to stop before arriving at the scenic Great Lake. Aurora images were taken toward the north -- but over land, not sea. While waiting for a second round of auroras, a peculiar band of light was noticed to the west.  Slowly, the photographer and friends realized that this western band was likely an unusual type of aurora: a Strong Thermal Emission Velocity Enhancement (STEVE). Moreover, this STEVE was putting on quite a show: appearing intertwined with the central band of our Milky Way Galaxy while intersecting the horizon just near the end of the country road. After capturing this cosmic X on camera, the photographer paused to appreciate the unexpected awesomeness of finding extraordinary beauty in an ordinary setting.     Your Sky Surprise: What picture did APOD feature on your birthday? (post 1995)

Image credit: Theresa Clarke
The Deep Lagoon (2023-09-28)

Ridges of glowing interstellar gas and dark dust clouds inhabit the turbulent, cosmic depths of the Lagoon Nebula. Also known as M8, The bright star forming region is about 5,000 light-years distant. It makes for a popular stop on telescopic tours of the constellation Sagittarius toward the center of our Milky Way Galaxy. Dominated by the telltale red emission of ionized hydrogen atoms recombining with stripped electrons, this deep telescopic view of the Lagoon's central reaches is about 40 light-years across. The bright hourglass shape near the center of the frame is gas ionized and sculpted by energetic radiation and extreme stellar winds from a massive young star.

Image credit: Josep Drudis
Back from Bennu (2023-09-29)

Back from asteroid 101955 Bennu, a 110-pound, 31-inch wide sample return capsule rests in a desert on planet Earth in this photo, taken at the Department of Defense Utah Test and Training Range near Salt Lake City last Sunday, September 24. Dropped off by the OSIRIS-Rex spacecraft, the capsule looks charred from the extreme temperatures experienced during its blistering descent through Earth's dense atmosphere. OSIRIS-Rex began its home-ward journey from Bennu in May of 2021. Delivered to NASA’s Johnson Space Center in Houston on September 25, the capsule's canister is expected to contain an uncontaminated sample of about a half pound (250 grams) of Bennu's loosely packed regolith. Working in a new laboratory designed for the OSIRIS-REx mission, scientists and engineers will complete the canister disassembly process, and plan to unveil the sample of the near-Earth asteroid in a broadcast event on October 11.
A Harvest Moon over Tuscany (2023-09-30)

For northern hemisphere dwellers, September's Full Moon was the Harvest Moon. Reflecting warm hues at sunset, it rises behind cypress trees huddled on a hill top in Tuscany, Italy in this telephoto view from September 28.  Famed in festival, story, and song, Harvest Moon is just the traditional name of the full moon nearest the autumnal equinox.  According to lore the name is a fitting one. Despite the diminishing daylight hours as the growing season drew to a close, farmers could harvest crops by the light of a full moon shining on from dusk to dawn. This Harvest Moon was also known to some as a supermoon, a term becoming a traditional name for a full moon near perigee. It was the fourth and final supermoon for 2023.

Image credit: Antonio Tartarini
A Desert Eclipse (2023-10-01)

A good place to see a ring-of-fire eclipse, it seemed, would be from a desert. In a desert, there should be relatively few obscuring clouds and trees.  Therefore late December of 2019, a group of photographers traveled to the United Arab Emirates and Rub al-Khali, the largest continuous sand desert in world, to capture clear images of an unusual eclipse that would be passing over.  A ring-of-fire eclipse is an annular eclipse that occurs when the Moon is far enough away on its elliptical orbit around the Earth so that it appears too small, angularly, to cover the entire Sun. At the maximum of an annular eclipse, the edges of the Sun can be seen all around the edges of the Moon, so that the Moon appears to be a dark spot that covers most -- but not all -- of the Sun. This particular eclipse, they knew, would peak soon after sunrise.  After seeking out such a dry and barren place, it turned out that some of the most interesting eclipse images actually included a tree in the foreground, because, in addition to the sand dunes, the tree gave the surreal background a contrasting sense of normalcy, scale, and texture.  On Saturday, October 14, a new ring of fire will be visible through clear skies from a thin swath crossing both North and South America.

Image credit: Maxime Daviron
Sprite Lightning in High Definition (2023-10-02)

Sometimes lightning occurs out near space.  One such lightning type is red sprite lightning, which has only been photographed and studied on Earth over the past 25 years.  The origins of all types of lightning remain topics for research, and scientists are still trying to figure out why red sprite lightning occurs at all.  Research has shown that following a powerful positive cloud-to-ground lightning strike, red sprites may start as 100-meter balls of ionized air that shoot down from about 80-km high at 10 percent the speed of light. They are quickly followed by a group of upward streaking ionized balls. Featured here is an extraordinarily high-resolution image of a group of red sprites. This image is a single frame lasting only 1/25th of a second from a video taken above Castelnaud Castle in Dordogne, France, about three weeks ago. The sprites quickly vanished -- no sprites were visible even on the very next video frame.

Image credit: Nicolas Escurat
MyCn 18: The Engraved Hourglass Planetary Nebula (2023-10-03)

Do you see the hourglass shape -- or does it see you?  If you can picture it, the rings of MyCn 18 trace the outline of an hourglass -- although one with an unusual eye in its center.  Either way, the sands of time are running out for the central star of this hourglass-shaped planetary nebula. With its nuclear fuel exhausted, this brief, spectacular, closing phase of a Sun-like star's life occurs as its outer layers are ejected - its core becoming a cooling, fading white dwarf. In 1995, astronomers used the Hubble Space Telescope (HST) to make a series of images of planetary nebulae, including the one featured here.  Pictured, delicate rings of colorful glowing gas (nitrogen-red, hydrogen-green, and oxygen-blue) outline the tenuous walls of the hourglass. The unprecedented sharpness of the Hubble images has revealed surprising details of the nebula ejection process that are helping to resolve the outstanding mysteries of the complex shapes and symmetries of planetary nebulas like MyCn 18.

Image credit: NASA, 
ESA, 
Hubble, 
HLA;
Processing & Copyright: 
Harshwardhan Pathak