juliensimon/nasa-apod huggingface dataset:
Messier 24: Sagittarius Star Cloud (2023-06-28)

Unlike most entries in Charles Messier's famous catalog of deep sky objects, M24 is not a bright galaxy, star cluster, or nebula. It's a gap in nearby, obscuring interstellar dust clouds that allows a view of the distant stars in the Sagittarius spiral arm of our Milky Way galaxy. Direct your gaze through this gap with binoculars or small telescope and you are looking through a window over 300 light-years wide at stars some 10,000 light-years or more from Earth. Sometimes called the Small Sagittarius Star Cloud, M24's luminous stars fill this gorgeous starscape.  Covering over 3 degrees or the width of 6 full moons in the constellation Sagittarius, the telescopic field of view includes dark markings B92 and B93 near center, along with other clouds of dust and glowing nebulae toward the center of the Milky Way.

Image credit: Emmanuel Astronomono
A Message from the Gravitational Universe (2023-06-29)

Monitoring 68 pulsars with very large radio telescopes, the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) has uncovered evidence for the gravitational wave (GW) background by carefully measuring slight shifts in the arrival times of pulses.  These shifts are correlated between different pulsars in a way that indicates that they are caused by GWs. This GW background is likely due to hundreds of thousands or even millions of supermassive black hole binaries.  Teams in Europe, Asia and Australia have also independently reported their results today. Previously, the LIGO and Virgo detectors have detected higher-frequency GWs from the merging of individual pairs of massive orbiting objects, such as stellar-mass black holes. The featured illustration highlights this spacetime-shaking result by depicting two orbiting supermassive black holes and several of the pulsars that would appear to have slight timing shifts.  The imprint these GWs make on spacetime itself is illustrated by a distorted grid.   Open Science: Browse 3,000+ codes in the Astrophysics Source Code Library
Orbits of Potentially Hazardous Asteroids (2023-06-30)

Are asteroids dangerous? Some are, but the likelihood of a dangerous asteroid striking the Earth during any given year is low. Because some past mass extinction events have been linked to asteroid impacts, however, humanity has made it a priority to find and catalog those asteroids that may one day affect life on Earth. Pictured here are the orbits of the over 1,000 known Potentially Hazardous Asteroids (PHAs). These documented tumbling boulders of rock and ice are over 140 meters across and will pass within 7.5 million kilometers of Earth -- about 20 times the distance to the Moon. Although none of them will strike the Earth in the next 100 years -- not all PHAs have been discovered, and past 100 years, many orbits become hard to predict. Were an asteroid of this size to impact the Earth, it could raise dangerous tsunamis, for example. To investigate Earth-saving strategies, NASA successfully tested the Double Asteroid Redirection Test (DART) mission last year. Of course, rocks and ice bits of much smaller size strike the Earth every day, usually pose no danger, and sometimes create memorable fireball and meteor displays.    Today is: Asteroid Day
Three Galaxies in Draco (2023-07-01)

This tantalizing trio of galaxies sometimes called the Draco Group, is located in the northern constellation of (you guessed it) Draco, the Dragon. From left to right are face-on spiral NGC 5985, elliptical galaxy NGC 5982, and edge-on spiral NGC 5981, all found within this single telescopic field of view that spans a little more than the width of the full moon. While the group is far too small to be a galaxy cluster, and has not been catalogued as a compact galaxy group, the three galaxies all do lie roughly 100 million light-years from planet Earth. Not as well known as other tight groupings of galaxies, the contrast in visual appearance still makes this triplet an attractive subject for astroimagers. On close examination with spectrographs, the bright core of striking spiral NGC 5985 shows prominent emission in specific wavelengths of light, prompting astronomers to classify it as a Seyfert, a type of active galaxy. This impressively deep exposure hints at a faint dim halo along with sharp-edged shells surrounding elliptical NGC 5982, evidence of past galactic mergers. It also reveals many even more distant background galaxies.

Image credit: David Vernet , Jean-François Bax , Serge Brunier
Milky Way and Aurora over Antarctica (2023-07-02)

It was one of the better skies of this long night. In parts of Antarctica, not only is it winter, but the Sun can spend weeks below the horizon. At China's Zhongshan Station, people sometimes venture out into the cold to photograph a spectacular night sky. The featured image from one such outing was taken in mid-July of 2015, just before the end of this polar night. Pointing up, the wide angle lens captured not only the ground at the bottom, but at the top as well.  In the foreground, a colleague is taking pictures. In the distance, a spherical satellite receiver and several windmills are visible. Numerous stars dot the night sky, including Sirius and Canopus. Far in the background, stretching overhead from horizon to horizon, is the central band of our Milky Way Galaxy. Even further in the distance, visible as extended smudges near the top, are the Large and Small Magellanic Clouds, satellite galaxies near our huge Milky Way Galaxy.   Explore the Universe: Random APOD Generator

Image credit: LI Hang
Venus in Ultraviolet from Akatsuki (2023-07-03)

Why is Venus so different from Earth?  To help find out, Japan launched the robotic Akatsuki spacecraft which entered orbit around Venus late in 2015 after an unplanned five-year adventure around the inner Solar System.  Even though Akatsuki was past its original planned lifetime, the spacecraft and instruments were operating so well that much of its original mission was reinstated. Also known as the Venus Climate Orbiter, Akatsuki's instruments investigated unknowns about Earth's sister planet, including whether volcanoes are still active, whether lightning occurs in the dense atmosphere, and why wind speeds greatly exceed the planet's rotation speed. In the featured image taken by Akatsuki's UVI camera, the day-side of Venus is seen shown with planet-scale V-shaped cloud pattern. The image displays three ultraviolet colors and indicates a dip in the relative abundance of sulfur dioxide shown in faint blue.  Analyses of Akatsuki images and data has shown, among other discoveries, that Venus has equatorial jet similar to Earth's jet stream.

Image credit: JAXA
Aurora over Icelandic Waterfall (2023-07-04)

It seemed like the sky exploded. The original idea was to photograph an aurora over a waterfall. After waiting for hours under opaque clouds, though, hope was running out. Others left. Then, unexpectedly, the clouds moved away. Suddenly, particles from a large solar magnetic storm were visible impacting the Earth's upper atmosphere with full effect. The night sky filled with colors and motion in a thrilling auroral display.  Struggling to steady the camera from high Earthly winds, the 34 exposures that compose the featured image were taken.  The resulting featured composite image shows the photogenic Godafoss (Goðafoss) waterfall in northern Iceland in front of a very active aurora in late February. The solar surface explosion that expelled the energetic particles occurred a few days before.  Our Sun is showing an impressive amount of surface activity as it approaches solar maximum, indicating that more impressive auroras are likely to appear in Earth's northern and southern sky over the next few years.

Image credit: Cari Letelier
A Map of the Observable Universe (2023-07-05)

What if you could see out to the edge of the observable universe? You would see galaxies, galaxies, galaxies, and then, well, quasars, which are the bright centers of distant galaxies.  To expand understanding of the very largest scales that humanity can see, a map of the galaxies and quasars found by the Sloan Digital Sky Survey from 2000 to 2020 -- out to near the edge of the observable universe -- has been composed. Featured here, one wedge from this survey encompasses about 200,000 galaxies and quasars out beyond a look-back time of 12 billion years and cosmological redshift 5.  Almost every dot in the nearby lower part of the illustration represents a galaxy, with redness indicating increasing redshift and distance. Similarly, almost every dot on the upper part represents a distant quasar, with blue-shaded dots being closer than red. Clearly shown among many discoveries, gravity between galaxies has caused the nearby universe to condense and become increasingly more filamentary than the distant universe.   More Detailed Maps: Related to Today's APOD

Image credit: B. Ménard & 
N. Shtarkman;
Data:  
SDSS, 
Planck, 
JHU, 
Sloan, 
NASA, 
ESA
Fireworks vs Supermoon (2023-07-06)

On July 4, an almost Full Moon rose in planet Earth's evening skies. Also known as a Buck Moon, the full lunar phase (full on July 3 at 11:39 UTC) was near perigee, the closest point in the Moon's almost monthly orbit around planet Earth. That qualified this July's Full Moon as a supermoon, the first of four supermoons in 2023. Seen from Cocoa Beach along Florida's Space Coast on July 4, any big, bright, beautiful Full Moon would still have to compete for attention though. July's super-moonrise was captured here against a super-colorful fireworks display.

Image credit: Michael Seeley
The Double Cluster in Perseus (2023-07-07)

This pretty starfield spans about three full moons (1.5 degrees) across the heroic northern constellation of Perseus. It holds the famous pair of open star clusters, h and Chi Persei. Also cataloged as NGC 869 (top) and NGC 884, both clusters are about 7,000 light-years away and contain stars much younger and hotter than the Sun.  Separated by only a few hundred light-years, the clusters are both 13 million years young based on the ages of their individual stars, evidence that they were likely a product of the same star-forming region. Always a rewarding sight in binoculars, the Double Cluster is even visible to the unaided eye from dark locations.

Image credit: Mårten Frosth
Stickney Crater (2023-07-08)

Stickney Crater, the largest crater on the martian moon Phobos, is named for Chloe Angeline Stickney Hall, mathematician and wife of astronomer Asaph Hall. Asaph Hall discovered both the Red Planet's moons in 1877. Over 9 kilometers across, Stickney is nearly half the diameter of Phobos itself, so large that the impact that blasted out the crater likely came close to shattering the tiny moon. This enhanced-color image of Stickney and surroundings was recorded by the HiRISE camera onboard the Mars Reconnaissance Orbiter as it passed within some six thousand kilometers of Phobos in March of 2008. Even though the surface gravity of asteroid-like Phobos is less than 1/1000th Earth's gravity, streaks suggest loose material slid down inside the crater walls over time. Light bluish regions near the crater's rim could indicate a relatively freshly exposed surface. The origin of the curious grooves along the surface is mysterious but may be related to tidal stresses experienced by close-orbiting Phobos or the crater-forming impact itself.
Doomed Star Eta Carinae (2023-07-09)

Carinae may be about to explode.  But no one knows when - it may be next year, it may be one million years from now. Eta Carinae's mass - about 100 times greater than our Sun - makes it an excellent candidate for a full blown supernova. Historical records do show that about 170 years ago Eta Carinae underwent an unusual outburst that made it one of the brightest stars in the southern sky.  Eta Carinae, in the Keyhole Nebula, is the only star currently thought to emit natural LASER light. This featured image brings out details in the unusual nebula that surrounds this rogue star.  Diffraction spikes, caused by the telescope, are visible as bright multi-colored streaks emanating from Eta Carinae's center.  Two distinct lobes of the Homunculus Nebula encompass the hot central region, while some strange radial streaks are visible in red extending toward the image right. The lobes are filled with lanes of gas and dust which absorb the blue and ultraviolet light emitted near the center.  The streaks, however, remain unexplained.

Image credit: NASA, 
ESA, 
Hubble;
 Processing & 
License: 
Judy Schmidt
Stars, Dust and Nebula in NGC 6559 (2023-07-10)

When stars form, pandemonium reigns.  A textbook case is the star forming region NGC 6559.  Visible in the featured image are red glowing emission nebulas of hydrogen, blue reflection nebulas of dust, dark absorption nebulas of dust, and the stars that formed from them.  The first massive stars formed from the dense gas will emit energetic light and winds that erode, fragment, and sculpt their birthplace.  And then they explode. The resulting morass can be as beautiful as it is complex.  After tens of millions of years, the dust boils away, the gas gets swept away, and all that is left is a bare open cluster of stars.

Image credit: Adam Block,
Telescope Live
Sunspots on an Active Sun (2023-07-11)

Why is our Sun so active now? No one is sure.  An increase in surface activity was expected because our Sun is approaching solar maximum in 2025. However, last month our Sun sprouted more sunspots than in any month during the entire previous 11-year solar cycle -- and even dating back to 2002. The featured picture is a composite of images taken every day from January to June by NASA's Solar Dynamic Observatory.  Showing a high abundance of sunspots, large individual spots can be tracked across the Sun's disk, left to right, over about two weeks.  As a solar cycle continues, sunspots typically appear closer to the equator.  Sunspots are just one way that our Sun displays surface activity -- another is flares and coronal mass ejections (CMEs) that expel particles out into the Solar System. Since these particles can affect astronauts and electronics, tracking surface disturbances is of more than aesthetic value.  Conversely, solar activity can have very high aesthetic value -- in the Earth's atmosphere when they trigger aurora.
Rings and Bar of Spiral Galaxy NGC 1398 (2023-07-12)

Why do some spiral galaxies have a ring around the center? Spiral galaxy NGC 1398 not only has a ring of pearly stars, gas and dust around its center, but a bar of stars and gas across its center, and spiral arms that appear like ribbons farther out.  The featured deep image from Observatorio El Sauce in Chile shows the grand spiral galaxy in impressive detail. NGC 1398 lies about 65 million light years distant, meaning the light we see today left this galaxy when dinosaurs were disappearing from the Earth.  The photogenic galaxy is visible with a small telescope toward the constellation of the Furnace (Fornax). The ring near the center is likely an expanding density wave of star formation, caused either by a gravitational encounter with another galaxy, or by the galaxy's own gravitational asymmetries.
Webb's Rho Ophiuchi (2023-07-13)

A mere 390 light-years away, Sun-like stars and future planetary systems are forming in the Rho Ophiuchi molecular cloud complex, the closest star-forming region to our fair planet. The James Webb Space Telescope's NIRCam peered into the nearby natal chaos to capture this infrared image at an inspiring scale. The spectacular cosmic snapshot was released to celebrate the successful first year of Webb's exploration of the Universe. The frame spans less than a light-year across the Rho Ophiuchi region and contains about 50 young stars. Brighter stars clearly sport Webb's characteristic pattern of diffraction spikes. Huge jets of shocked molecular hydrogen blasting from newborn stars are red in the image, with the large, yellowish dusty cavity carved out by the energetic young star near its center. Near some stars in the stunning image are shadows cast by their protoplanetary disks.
Comet C/2023 E1 ATLAS near Perihelion (2023-07-14)

Comet C/2023 E1 (ATLAS) was just spotted in March, another comet found by the NASA funded Asteroid Terrestrial-impact Last Alert System.  On July 1 this Comet ATLAS reached perihelion, its closest approach to the Sun. Days later the telescopic comet was captured in this frame sporting a pretty greenish coma and faint, narrow ion tail against a background of stars in the far northern constellation Ursa Minor.  This comet's closest approach to Earth is still to come though. On August 18 this visitor to the inner Solar System will be a mere 3 light-minutes or so from our fair planet. Based on its inclination to the ecliptic plane and orbital period of about 85 years C/2023 E1 (ATLAS) is considered a Halley-type comet.

Image credit: Dan Bartlett
Webb's First Deep Field (2023-07-15)

This stunning infrared image was released one year ago as the James Webb Space Telescope began its exploration of the cosmos. The view of the early Universe toward the southern constellation Volans was achieved in 12.5 hours of exposure with Webb's NIRCam instrument. Of course the stars with six spikes are well within our own Milky Way. Their diffraction pattern is characteristic of Webb's 18 hexagonal mirror segments operating together as a single 6.5 meter diameter primary mirror. The thousands of galaxies flooding the field of view are members of the distant galaxy cluster SMACS0723-73, some 4.6 billion light-years away. Luminous arcs that seem to infest the deep field are even more distant galaxies though. Their images are distorted and magnified by the dark matter dominated mass of the galaxy cluster, an effect known as gravitational lensing. Analyzing light from two separate arcs below the bright spiky star, Webb's NIRISS instrument indicates the arcs are both images of the same background galaxy. And that galaxy's light took about 9.5 billion years to reach the James Webb Space Telescope.
Meteor and Milky Way over the Alps (2023-07-16)

Now this was a view with a thrill. From Mount Tschirgant in the Alps, you can see not only nearby towns and distant Tyrolean peaks, but also, weather permitting, stars, nebulas, and the band of the Milky Way Galaxy. What made the arduous climb worthwhile this night, though, was another peak -- the peak of the 2018 Perseids Meteor Shower. As hoped, dispersing clouds allowed a picturesque sky-gazing session that included many faint meteors, all while a carefully positioned camera took a series of exposures. Suddenly, a thrilling meteor -- bright and colorful -- slashed down right next to the nearly vertical band of the Milky Way.  As luck would have it, the camera caught it too.  Therefore, a new image in the series was quickly taken with one of the sky-gazers posing on the nearby peak. Later, all of the images were digitally combined.

Image credit: Nicholas Roemmelt
(Venture Photography)
Shells and Arcs around Star CW Leonis (2023-07-17)

What's happening around this star? No one is sure. CW Leonis is the closest carbon star, a star that appears orange because of atmospheric carbon dispersed from interior nuclear fusion. But CW Leonis also appears engulfed in a gaseous carbon-rich nebula. What causes the nebula's complexity is unknown, but its geometry of shells and arcs are surely intriguing. The featured image by the Hubble Space Telescope details this complexity. The low surface gravity of carbon stars enhances their ability to expel carbon and carbon compounds into space. Some of this carbon ends up forming dark dust that is commonly seen in the nebulas of young star-forming regions and the disks of galaxies.  Humans and all Earth-based life are carbon-based, and at least some of our carbon was likely once circulating in the atmospheres of near-death stars like carbon stars.
Milky Way above La Palma Observatory (2023-07-18)

What's happening in the night sky? To help find out, telescopes all over the globe will be pointing into deep space.  Investigations will include trying to understand the early universe, finding and tracking Earth-menacing asteroids, searching for planets that might contain extra-terrestrial life, and monitoring stars to help better understand our Sun. The featured composite includes foreground and background images taken in April from a mountaintop on La Palma island in the Canary Islands of Spain.  Pictured, several telescopes from the Roque de los Muchachos Observatory are shown in front of a dark night sky. Telescopes in the foreground include, left to right, Magic 1, Galileo, Magic 2, Gran Telescopio Canarias, and LST. Sky highlights in the background include the central band of our Milky Way Galaxy, the constellations of Sagittarius, Ophiuchus and Scorpius, the red-glowing Eagle and Lagoon Nebulas, and the stars Alrami and Antares.  Due to observatories like this, humanity has understood more about our night sky in the past 100 years than ever before in all of human history.

Image credit: Marcin Rosadziński
Chandrayaan-3 Launches to the Moon (2023-07-19)

Birds don't fly this high.  Airplanes don't go this fast.  The Statue of Liberty weighs less.  No species other than human can even comprehend what is going on, nor could any human just a millennium ago. The launch of a rocket bound for space is an event that inspires awe and challenges description.  Pictured here last week, the Indian Space Research Organization's  LVM3 rocket blasted off from the Satish Dhawan Space Centre on Sriharikota Island, India.  From a standing start, the 600,000+ kilogram rocket ship lifted the massive Chandrayaan-3 off the Earth. The Chandrayaan-3 mission is scheduled to reach the Moon in late August and land a robotic rover near the lunar South Pole. Rockets bound for space are now launched from somewhere on Earth every few days.

Image credit: Sruthi Suresh 
(Space Group)
M64: The Black Eye Galaxy Close Up (2023-07-20)

This magnificent spiral galaxy is Messier 64, often called the Black Eye Galaxy or the Sleeping Beauty Galaxy for its dark-lidded appearance in telescopic views. The spiral's central region, about 7,400 light-years across, is pictured in this reprocessed image from the Hubble Space Telescope. M64 lies some 17 million light-years distant in the otherwise well-groomed northern constellation Coma Berenices. The enormous dust clouds partially obscuring M64's central region are laced with young, blue star clusters and the reddish glow of hydrogen associated with star forming regions.  But imposing clouds of dust are not this galaxy's only peculiar feature. Observations show that M64 is actually composed of two concentric, counter-rotating systems. While all the stars in M64 rotate in the same direction as the interstellar gas in the galaxy's central region, gas in the outer regions, extending to about 40,000 light-years, rotates in the opposite direction. The dusty eye and bizarre rotation are likely the result of a billion year old merger of two different galaxies.
Galactic Cirrus: Mandel Wilson 9 (2023-07-21)

The combined light of stars along the Milky Way are reflected by these cosmic dust clouds that soar 300 light-years or so above the plane of our galaxy. Known to some as integrated flux nebulae and commonly found at high galactic latitudes, the dusty galactic cirrus clouds are faint. But they can be traced over large regions of the sky toward the North and South Galactic poles. Along with the reflection of starlight, studies indicate the dust clouds produce a faint reddish luminescence as interstellar dust grains convert invisible ultraviolet radiation to visible red light. Also capturing nearby Milky Way stars and distant background galaxies, this remarkably deep, wide-field image explores a complex of faint galactic cirrus known as Mandel Wilson 9. It spans over three degrees across planet Earth's skies toward the far southern constellation Apus.

Image credit: Gabriel Rodrigues Santos