juliensimon/nasa-apod huggingface dataset:
Saturn at the Moon's Edge (2024-07-27)

Saturn now rises before midnight in planet Earth's sky. On July 24, the naked-eye planet was in close conjunction, close on the sky, to a waning gibbous Moon. But from some locations on planet Earth the ringed gas giant was occulted, disappearing behind the Moon for about an hour from skies over parts of Asia and Africa. Because the Moon and bright planets wander through the sky near the ecliptic plane, such occultation events are not uncommon, but they can be dramatic. In this telescopic view from Nanjing, Jiangsu, China, Saturn is caught moments before its disappearance behind the lunar disk. The snapshot gives the illusion that Saturn hangs just above Glushko crater, a 43 kilometer diameter, young, ray crater near the Moon's western edge. Of course, the Moon is 400 thousand kilometers away, compared to Saturn's distance of 1.4 billion kilometers.

Image credit: Chengcheng Xu
Sun Dance (2024-07-28)

Sometimes, the surface of our Sun seems to dance. In the middle of 2012, for example, NASA's Sun-orbiting Solar Dynamic Observatory spacecraft imaged an impressive prominence that seemed to perform a running dive roll like an acrobatic dancer.  The dramatic explosion was captured in ultraviolet light in the featured time-lapse video covering about three hours. A looping magnetic field directed the flow of hot plasma on the Sun. The scale of the   dancing prominence is huge -- the entire Earth would easily fit under the flowing   arch of hot gas.  A quiescent prominence typically lasts about a month and may erupt in a Coronal Mass Ejection (CME), expelling hot gas into the Solar System.  The energy mechanism that creates a solar prominence is still a topic of research.  Like in 2012, this year the Sun's surface is again quite active and features many filaments and prominences.
Milky Way over Uluru (2024-07-29)

What's happening above Uluru?  A United Nations World Heritage Site, Uluru  is an extraordinary 350-meter high mountain in central Australia that rises sharply from nearly flat surroundings. Composed of sandstone, Uluru has slowly formed over the past 300 million years as softer rock eroded away.  The Uluru region has been a home to humans for over 22,000 years. Recorded  last month, the starry sky above Uluru includes the central band of our Milky Way galaxy, complete with complex dark filaments of dust, bright red emission nebulas, and billions of stars.

Image credit: Max Inwood
Arp 142: Interacting Galaxies from Webb (2024-07-30)

To some, it looks like a penguin. But to people who study the universe, it is an interesting example of two big galaxies interacting. Just a few hundred million years ago, the upper NGC 2936 was likely a normal spiral galaxy: spinning, creating stars, and minding its own business.  Then it got too close to the massive elliptical galaxy NGC 2937, below, and took a dive.  Together known as Arp 142, they are featured in this new Webb infrared image, while a visible light Hubble image appears in comparison.  NGC 2936 is not only being deflected, but distorted, by this close gravitational interaction.  When massive galaxies pass near each other, gas is typically condensed from which new stars form.  A young group of stars appears as the nose of the penguin toward the right of the upper galaxy, while in the center of the spiral, bright stars together appear as an eye.  Before a billion years, the two galaxies will likely merge into one larger galaxy.   Explore Your Universe: Random APOD Generator
Leopard Spots on Martian Rocks (2024-07-31)

What is creating these unusual spots? Light-colored spots on Martian rocks, each surrounded by a dark border, were discovered earlier this month by NASA's Perseverance Rover currently exploring Mars.  Dubbed leopard spots because of their seemingly similarity to markings on famous Earth-bound predators, these curious patterns are being studied with the possibility they were created by ancient Martian life.  The pictured spots measure only millimeters across and were discovered on a larger rock named Cheyava Falls.  The exciting but unproven speculation is that long ago, microbes generated energy with chemical reactions that turned rock from red to white while leaving a dark ring, like some similarly appearing spots on Earth rocks. Although other non-biological explanations may ultimately prevail, speculation focusing on this potential biological origin is causing much intrigue.    New Mirror: APOD is now available from Brazil in Portuguese
Comet Olbers over Kunetice Castle (2024-08-01)

A visitor to the inner solar system every 70 years or so, Comet 13P/Olbers reached its most recent perihelion, or closest approach to the Sun, on June 30. Now on a return voyage to the distant Oort Cloud, the Halley-type comet is recorded here sweeping through northern summer night skies over historic Kunetice Castle, Czech Republic. The composite of tracked exposures for comet and sky, showing the comet's broad dust tail, brighter coma, and long ion tail buffeted by storms and winds from the Sun, and fixed exposures for foreground landscape was recorded on July 28. The comet is about 16 light-minutes beyond the castle and seen against faint background stars below the northern constellation Ursa Major. The hilltop castle dates to the 15th century, while Heinrich Olbers discovered the comet in 1815. Captured here low in northwestern skies just after sunset Comet Olbers, for now, offers skywatchers on planet Earth rewarding telescopic and binocular views. Comet 13P/Olbers' next perihelion passage will be in 2094.

Image credit: Petr Horálek
Mars Passing By (2024-08-02)

As Mars wanders through Earth's night, it passes about 5 degrees south of the Pleiades star cluster in this composite astrophoto. The skyview was constructed from a series of images captured over a run of 16 consecutive clear nights beginning on July 12. Mars' march across the field of view begins at the far right, the planet's ruddy hue showing a nice contrast with the blue Pleiades stars. Moving much faster across the sky against the distant stars, the fourth planet from the Sun easily passes seventh planet Uranus. Red planet Mars and the ice giant world were in close conjunction, about 1/2 degree apart, on July 16. Continuing its rapid eastward trek, Mars has now left the sister stars and outer planet behind though, passing north of red giant star Aldebaran. Mars will come within about 1/3 degree of Jupiter in planet Earth's sky on August 14.

Image credit: Tunc Tezel
Glory and Fog Bow (2024-08-03)

On a road trip up Mount Uludağ in Bursa province, Turkey these motorcyclists found themselves above low clouds and fog in late June. With the bright Sun directly behind them, the view down the side of the great mountain revealed a beautiful, atmospheric glory and fog bow. Known to some as the heiligenschein or the Specter of the Brocken, a glory can also sometimes be seen from airplanes or even high buildings. It often appears to be a dark giant surrounded by a bright halo. Of course the dark giant is just the shadow of the observer (90MB video) cast opposite the Sun. The clouds and fog are composed of very small water droplets, smaller than rain drops, that refract and reflect sunlight to create the glory's colorful halo and this more extensive fog bow.

Image credit: Cem Özkeser
Gaia: Here Comes the Sun (2024-08-04)

What would it look like to return home from outside our galaxy? Although designed to answer greater questions, data from ESA's robotic Gaia mission is helping to provide a uniquely modern perspective on humanity's place in the universe.  Gaia orbits the Sun near the Earth and resolves stars' positions so precisely that it can determine a slight shift from its changing vantage point over the course of a year, a shift that is proportionately smaller for more distant stars -- and so determines distance.  In the first sequence of the video, an illustration of the Milky Way is shown that soon resolves into a three-dimensional visualization of Gaia star data.  A few notable stars are labelled with their common names, while others stars are labelled with numbers from a Gaia catalog. Eventually, the viewer arrives in our stellar neighborhood where many stars were tracked by Gaia, and soon at our home star Sol, the Sun. At the video's end, the reflective glow of Sol's third planet becomes visible: Earth.
Milky Way Over Tunisia (2024-08-05)

That's no moon. On the ground, that's the Lars Homestead in Tunisia. And that's not just any galaxy. That's the central band of our own Milky Way galaxy. Last, that's not just any meteor. It is a bright fireball likely from last year's Perseids meteor shower. The featured image composite combines consecutive exposures taken by the same camera from the same location.  This year's Perseids peak during the coming weekend is expected to show the most meteors after the first quarter moon sets, near midnight.  To best experience a meteor shower, you should have clear and dark skies, a comfortable seat, and patience.

Image credit: Makrem Larnaout
Storm Cloud Over Texas (2024-08-06)

What makes this storm cloud so colorful?  First, the cloud itself is composed of millions of tiny droplets of water and ice.  Its bottom is almost completely flat -- but this isn't unusual.  Bottom flatness in clouds is generally caused by air temperature dropping as you go up, and that above a specific height, water-saturated air condenses out water droplets.  The shape of the cloud middle is caused by a water-droplet-laden column of air being blown upward.  Most unusual, though, are the orange and yellow colors.  Both colors are caused by the cloud's water drops reflecting sunlight. The orange color in the cloud's middle and bottom sections are reflections of a nearly red sunset.  In contrast, the yellow color of the cloud's top results from reflection of light from a not-yet-setting Sun, where some -- but less -- blue light is being scattered away. Appearing to float above the plains in Texas, the featured impressive image of a dynamic cumulonimbus cloud was captured in 2021 while investigating a tornado.

Image credit: Laura Rowe (Used with permission)
Milky Way Behind Three Merlons (2024-08-07)

To some, they look like battlements, here protecting us against the center of the Milky Way. The Three Merlons, also called the Three Peaks of Lavaredo, stand tall today because they are made of dense dolomite rock which has better resisted erosion than surrounding softer rock. They formed about 250 million years ago and so are comparable in age with one of the great extinctions of life on Earth. A leading hypothesis is that this great extinction was triggered by an asteroid about 10-km across, larger in size than Mount Everest, impacting the Earth. Humans have gazed up at the stars in the Milky Way and beyond for centuries, making these battlefield-like formations, based in the Sexten Dolomites, a popular place for current and ancient astronomers.

Image credit: Donato Lioce; 
Text: Natalia Lewandowska 
(SUNY Oswego)
Periodic Comet Swift-Tuttle (2024-08-08)

A Halley-type comet with an orbital period of about 133 years, Comet 109P/Swift-Tuttle is recognized as the parent of the annual Perseid Meteor Shower. The comet's last visit to the inner Solar System was in 1992. Then, it did not become easily visible to the naked eye, but it did become bright enough to see from most locations with binoculars and small telescopes. This stunning color image of Swift-Tuttle's greenish coma, long ion tail and dust tail was recorded using film on November 24, 1992. That was about 16 days after the large periodic comet's closest approach to Earth. Comet Swift-Tuttle is expected to next make an impressive appearance in night skies in 2126. Meanwhile, dusty cometary debris left along the orbit of Swift-Tuttle will continue to be swept up creating planet Earth's best-known July and August meteor shower.

Image credit: Gerald Rhemann
A Perseid Below (2024-08-09)

Denizens of planet Earth typically watch meteor showers by looking up. But this remarkable view, captured on August 13, 2011 by astronaut Ron Garan, caught a Perseid meteor by looking down. From Garan's perspective on board the International Space Station orbiting at an altitude of about 380 kilometers, the Perseid meteors streak below, swept up dust from comet Swift-Tuttle. The vaporizing comet dust grains are traveling at about 60 kilometers per second through the denser atmosphere around 100 kilometers above Earth's surface. In this case, the foreshortened meteor flash is near frame center, below the curving limb of the Earth and a layer of greenish airglow, just below bright star Arcturus. Want to look up at a meteor shower?  You're in luck, as the 2024 Perseid meteor shower is active now and predicted to peak near August 12. With interfering bright moonlight absent, this year you'll likely see many Perseid meteors under clear, dark skies after midnight.
The Light, Dark, and Dusty Trifid (2024-08-10)

Messier 20, popularly known as the Trifid Nebula, lies about 5,000 light-years away toward the nebula rich constellation Sagittarius. A star forming region in the plane of our galaxy, the Trifid does illustrate three different types of astronomical nebulae; red emission nebulae dominated by light from hydrogen atoms, blue reflection nebulae produced by dust reflecting starlight, and dark nebulae where dense dust clouds appear in silhouette. The reddish emission region, roughly separated into three parts by obscuring dust lanes, is what lends the Trifid its popular name. The cosmic cloud complex is over 40 light-years across and would cover the area of a full moon on planet Earth's sky. But the Trifid Nebula is too faint to be seen by the unaided eye. Over 75 hours of image data captured under dark night skies was used to create this stunning telescopic view.  Watch: The Perseid Meteor Shower

Image credit: Robert Edelmaier and Gabriele Gegenbauer
Animation: Perseid Meteor Shower (2024-08-11)

Where do Perseid meteors come from? Mostly small bits of stony grit, Perseid meteoroids were once expelled from Comet Swift-Tuttle and continue to follow this comet's orbit as they slowly disperse.  The featured animation depicts the entire meteoroid stream as it orbits our Sun.  When the Earth nears this stream, as it does every year, the Perseid Meteor Shower occurs.  Highlighted as bright in the animation, comet debris this size is usually so dim it is practically undetectable.  Only a small fraction of this debris will enter the Earth's atmosphere, heat up and disintegrate brightly.  Tonight and the next few nights promise some of the better skies to view the Perseid shower as well as other active showers because the first quarter moon will be absent from the sky from midnight onward.   Your Sky Surprise: What picture did APOD feature on your birthday? (post 1995)
Perseid Meteors over Stonehenge (2024-08-12)

What's happening in the sky above Stonehenge? A meteor shower: specifically, the Perseid meteor shower. A few nights ago, after the sky darkened, many images of meteors from this year's Perseids were captured separately and merged into a single frame. Although the meteors all traveled on straight paths, these paths appear slightly curved by the wide-angle lens of the capturing camera. The meteor streaks can all be traced back to a single point on the sky called the radiant, here just off the top of the frame in the constellation of Perseus. The same camera took a deep image of the background sky that brought up the central band of our Milky Way galaxy running nearly vertical through the image center. The featured image was taken from Wiltshire, England, being careful to include, at the bottom, the famous astronomical monument of Stonehenge. Although the Perseids peaked last night, some Perseid meteors should still be visible for a few more nights.

Image credit: Josh Dury
Giant Jet from the International Space Station (2024-08-13)

What's that on the horizon? When circling the Earth on the International Space Station early last month, astronaut Matthew Dominick saw an unusual type of lightning just beyond the Earth's edge: a gigantic jet. The powerful jet appears on the left of the featured image in red and blue. Giant jet lightning has only been known about for the past 23 years. The atmospheric jets are associated with thunderstorms and extend upwards towards Earth's ionosphere.  The lower part of the frame shows the Earth at night, with Earth's thin atmosphere tinted green from airglow. City lights are visible, sometimes resolved, but usually creating diffuse white glows in intervening clouds.  The top of the frame reveals distant stars in the dark night sky. The nature of gigantic jets and their possible association with other types of Transient Luminous Events (TLEs) such as blue jets and red sprites remains an active topic of research.   Growing Gallery: Perseid Meteor Shower 2024 and Aurorae
Meteors and Aurora over Germany (2024-08-14)

This was an unusual night. For one thing, the night sky of August 11 and 12, earlier this week, occurred near the peak of the annual Perseid Meteor Shower. Therefore, meteors streaked across the dark night as small bits cast off from Comet Swift-Tuttle came crashing into the Earth's atmosphere. Even more unusually, for central Germany at least, the night sky glowed purple. The red-blue hue was due to aurora caused by an explosion of particles from the Sun a few days before. This auroral storm was so intense that it was seen as far south as Texas and Italy, in Earth's northern hemisphere.  The featured image composite was built from 7 exposures taken over 26 minutes from Ense, Germany. The Perseids occur predictably every August, but auroras visible this far south are more unusual and less predictable.   Gallery: Perseid Meteor Shower 2024 and Aurorae

Image credit: Chantal Anders
Late Night Vallentuna (2024-08-15)

Bright Mars and even brighter Jupiter are in close conjunction just above the pine trees in this post-midnight skyscape from Vallentuna, Sweden. Taken on August 12 during a geomagnetic storm, the snapshot records the glow of aurora borealis or northern lights, beaming from the left side of the frame. Of course on that date Perseid meteors rained through planet Earth's skies, grains of dust from the shower's parent, periodic comet Swift-Tuttle. The meteor streak at the upper right is a Perseid plowing through the atmosphere at about 60 kilometers per second. Also well-known in Earth's night sky, the bright Pleiades star cluster shines below the Perseid meteor streak. In Greek myth, the Pleiades were seven daughters of the astronomical titan Atlas and sea-nymph Pleione. The Pleiades and their parents' names are given to the cluster's nine brightest stars.   Gallery: Perseid Meteor Shower 2024 and Aurorae

Image credit: Clear Skies
Meteor Borealis (2024-08-16)

A single exposure made with a camera pointed almost due north on August 12 recorded this bright Perseid meteor in the night sky west of Halifax, Nova Scotia, Canada. The meteor's incandescent trace is fleeting. It appears to cross the stars of the Big Dipper, famous northern asterism and celestial kitchen utensil, while shimmering curtains of aurora borealis, also known as the northern lights, dance in the night. Doubling the wow factor for night skywatchers near the peak of this year's Perseid meteor shower auroral activity on planet Earth was enhanced by geomagnetic storms. The intense space weather was triggered by flares from an active Sun.   Gallery: Perseid Meteor Shower 2024 and Aurorae

Image credit: Jason Dain
Sky Full of Arcs (2024-08-17)

On August 11 a Rocket Lab Electron rocket launched from a rotating planet. With a small satellite on board its mission was dubbed A Sky Full of SARs (Synthetic Aperture Radar satellites), departing for low Earth orbit from Mahia Peninsula on New Zealand's north island. The fiery trace of the Electron's graceful launch arc is toward the east in this southern sea and skyscape, a composite of 50 consecutive frames taken over 2.5 hours. Fixed to a tripod, the camera was pointing directly at the South Celestial Pole, the extension of planet Earth's axis of rotation in to space. But no bright star marks that location in the southern hemisphere's night sky. Still, the South Celestial Pole is easy to spot. It lies at the center of the concentric star trail arcs that fill the skyward field of view.   Gallery: Perseid Meteor Shower 2024 and Aurorae

Image credit: Rory Gannaway
A Solar Prominence Eruption from SDO (2024-08-18)

One of the most spectacular solar sights is an erupting prominence. In 2011, NASA's Sun-orbiting Solar Dynamic Observatory spacecraft imaged an impressively large prominence erupting from the surface. The dramatic explosion was captured in ultraviolet light in the featured time lapse video covering 90 minutes, where a new frame was taken every 24 seconds.  The scale of the prominence is huge -- the entire Earth would easily fit under the flowing  curtain of hot gas.  A solar prominence is channeled and sometimes held above the Sun's surface by the Sun's magnetic field. A quiescent prominence typically lasts about a month and may erupt in a Coronal Mass Ejection (CME) expelling hot gas into the Solar System.  The energy mechanism that creates a solar prominence is a continuing topic of research.  Our Sun is again near solar maximum and so very active, featuring numerous erupting prominences and CMEs, one of which resulted in picturesque auroras just over the past week.
IC 5146: The Cocoon Nebula (2024-08-19)

Inside the Cocoon Nebula is a newly developing cluster of stars. Cataloged as IC 5146, the beautiful nebula is nearly 15 light-years wide. Soaring high in northern summer night skies, it's located some 4,000 light years away toward the constellation of the Swan (Cygnus).  Like other star forming regions, it stands out in red, glowing, hydrogen gas excited by young, hot stars, and dust-reflected starlight at the edge of an otherwise invisible molecular cloud.  In fact, the bright star found near the center of this nebula is likely only a few hundred thousand years old, powering the nebular glow as it clears out a cavity in the molecular cloud's star forming dust and gas. A 48-hour long integration resulted in this exceptionally deep color view tracing tantalizing features within and surrounding the dusty stellar nursery.

Image credit: Luis Romero Ventura
Supermoon Beyond the Temple of Poseidon (2024-08-20)

A supermoon occurred yesterday. And tonight's moon should also look impressive.  Supermoons appear slightly larger and brighter than most full moons because they reach their full phase when slightly nearer to the Earth -- closer than 90 percent of all full moons.  This supermoon was also a blue moon given the definition that it is the third of four full moons occurring during a single season.  Blue moons are not usually blue, and a different definition holds that a blue moon is the second full moon that occurs during a single month.  The featured image captured the blue supermoon right near its peak size yesterday as it was rising beyond the Temple of Poseidon in Greece. This supermoon is particularly unusual in that it is the first of four successive supermoons, the next three occurring in September, October, and November.
Fermi's 12-year All-Sky Gamma-ray Map (2024-08-21)

Forget X-ray vision — imagine what you could see with gamma-ray vision!  The featured all-sky map shows what the universe looks like to NASA's Fermi Gamma-ray Space Telescope.  Fermi sees light with energies about a billion times what the human eye can see, and the map combines 12 years of Fermi observations.  The colors represent the brightness of the gamma-ray sources, with brighter sources appearing lighter in color.  The prominent stripe across the middle is the central plane of our Milky Way galaxy.  Most of the red and yellow dots scattered above and below the Milky Way’s plane are very distant galaxies, while most of those within the plane are nearby pulsars.  The blue background that fills the image is the diffuse glow of gamma-rays from distant sources that are too dim to be detected individually.  Some gamma-ray sources remain unidentified and topics of research — currently no one knows what they are.