juliensimon/nasa-apod huggingface dataset:
Facing NGC 1232 (2024-04-18)

From our vantage point in the Milky Way Galaxy, we see NGC 1232 face-on. Nearly 200,000 light-years across, the big, beautiful spiral galaxy is located some 47 million light-years away in the flowing southern constellation of Eridanus. This sharp, multi-color, telescopic image of NGC 1232 includes remarkable details of the distant island universe. From the core outward, the galaxy's colors change from the yellowish light of old stars in the center to young blue star clusters and reddish star forming regions along the grand, sweeping spiral arms. NGC 1232's apparent, small, barred-spiral companion galaxy is cataloged as NGC 1232A. Distance estimates place it much farther though, around 300 million light-years away, and unlikely to be interacting with NGC 1232.  Of course, the prominent bright star with the spiky appearance is much closer than NGC 1232 and lies well within our own Milky Way.

Image credit: Neil Corke
The Great Carina Nebula (2024-04-19)

A jewel of the southern sky, the Great Carina Nebula is more modestly known as NGC 3372. One of our Galaxy's largest star forming regions, it spans over 300 light-years. Like the smaller, more northerly Great Orion Nebula, the Carina Nebula is easily visible to the unaided eye. But at a distance of 7,500 light-years it lies some 5 times farther away. This stunning telescopic view reveals remarkable details of the region's glowing filaments of interstellar gas and obscuring cosmic dust clouds. The Carina Nebula is home to young, extremely massive stars, including the still enigmatic variable Eta Carinae, a star with well over 100 times the mass of the Sun.  Eta Carinae is the bright star above the central dark notch in this field and left of the dusty Keyhole Nebula (NGC 3324).

Image credit: Demison Lopes
Diamonds in the Sky (2024-04-20)

When the dark shadow of the Moon raced across North America on April 8, sky watchers along the shadow's narrow central path were treated to a total solar eclipse. During the New Moon's shadow play diamonds glistened twice in the eclipse-darkened skies. The transient celestial jewels appeared immediately before and after the total eclipse phase. That's when the rays of a vanishing and then emerging sliver of solar disk are just visible behind the silhouetted Moon's edge, creating the appearance of a shiny diamond set in a dark ring. This dramatic timelapse composite from north-central Arkansas captures both diamond ring moments of this total solar eclipse. The diamond rings are separated by the ethereal beauty of the solar corona visible during totality.

Image credit: Wright Dobbs
Perijove 16: Passing Jupiter (2024-04-21)

Watch Juno zoom past Jupiter.  NASA's robotic spacecraft Juno is continuing on its now month-long, highly-elongated orbits around our Solar System's largest planet.  The featured video is from perijove 16, the sixteenth time that Juno passed near Jupiter since it arrived in mid-2016. Each perijove passes near a slightly different part of Jupiter's cloud tops.  This color-enhanced video has been digitally composed from 21 JunoCam still images, resulting in a 125-fold time-lapse. The video begins with Jupiter rising as Juno approaches from the north. As Juno reaches its closest view -- from about 3,500 kilometers over Jupiter's cloud tops -- the spacecraft captures the great planet in tremendous detail. Juno passes light zones and dark belts of clouds that circle the planet, as well as numerous swirling circular storms, many of which are larger than hurricanes on Earth.  As Juno moves away, the remarkable dolphin-shaped cloud is visible.  After the perijove, Jupiter recedes into the distance, now displaying the unusual clouds that appear over Jupiter's south.  To get desired science data, Juno swoops so close to Jupiter that its instruments are exposed to very high levels of radiation.
Moon and Smoke Rings from Mt. Etna (2024-04-22)

Yes, but can your volcano do this? To the surprise of some, Mt. Etna emits, on occasion, smoke rings. Technically known as vortex rings, the walls of the volcano slightly slow the outside of emitted smoke puffs, causing the inside gas to move faster.  A circle of low pressure develops so that the emitted puff of volcanic gas and ash loops around in a ring, a familiar geometric structure that can be surprisingly stable as it rises. Smoke rings are quite rare and need a coincidence of the right geometry  of the vent, the right speed of ejected smoke, and the relative calmness of the outside atmosphere.  In the featured image taken about two weeks ago from Gangi, Sicily, Italy, multiple volcanic smoke rings are visible.  The scene is shaded by the red light of a dawn Sun, while a crescent Moon is visible in the background.

Image credit: Dario Giannobile
Contrail Shadow X (2024-04-23)

What created this giant X in the clouds? It was the shadow of contrails. When airplanes fly, humid engine exhaust may form water droplets that might freeze in Earth's cold upper atmosphere.  These persistent streams of water and ice scatter light from the Sun above and so appear bright. These contrails cast long shadows.  That was just the case over Istanbul, Türkiye, earlier this month. Contrails occur all over planet Earth and, generally, warm the Earth when the trap infrared light but cool the Earth when they efficiently reflect sunlight. The image was taken by a surprised photographer in the morning on the way to work.

Image credit: Fatih Ekmen
Dragon's Egg Bipolar Emission Nebula (2024-04-24)

How did a star form this beautiful nebula?  In the middle of emission nebula NGC 6164 is an unusually massive star.  The central star has been compared to an oyster's pearl and an egg protected by the mythical sky dragons of Ara.  The star, visible in the center of the featured image and catalogued as HD 148937, is so hot that the ultraviolet light it emits heats up gas that surrounds it.  That gas was likely thrown off from the star previously, possibly the result of a gravitational interaction with a looping stellar companion.  Expelled material might have been channeled by the magnetic field of the massive star, in all creating the symmetric shape of the bipolar nebula.  NGC 6164 spans about four light years and is located about 3,600 light years away toward the southern constellation Norma.   New Mirror: APOD now available via WhatsApp

Image credit: Rowan Prangley
NGC 604: Giant Stellar Nursery (2024-04-25)

Located some 3 million light-years away in the arms of nearby spiral galaxy M33, giant stellar nursery NGC 604 is about 1,300 light-years across. That's nearly 100 times the size of the Milky Way's Orion Nebula, the closest large star forming region to planet Earth. In fact, among the star forming regions within the Local Group of galaxies, NGC 604 is second in size only to 30 Doradus, also known as the Tarantula Nebula in the Large Magellanic Cloud. Cavernous bubbles and cavities in NGC 604 fill this stunning infrared image from the James Webb Space Telescope's NIRCam. They are carved out by energetic stellar winds from the region's more than 200 hot, massive, young stars, all still in early stages of their lives.
Regulus and the Dwarf Galaxy (2024-04-26)

In northern hemisphere spring, bright star Regulus is easy to spot above the eastern horizon. The alpha star of the constellation Leo, Regulus is the spiky star centered in this telescopic field of view. A mere 79 light-years distant, Regulus is a hot, rapidly spinning star that is known to be part of a multiple star system. Not quite lost in the glare, the fuzzy patch just below Regulus is diffuse starlight from small galaxy Leo I. Leo I is a dwarf spheroidal galaxy, a member of the Local Group of galaxies dominated by our Milky Way Galaxy and the Andromeda Galaxy (M31). About 800 thousand light-years away, Leo I is thought to be the most distant of the known small satellite galaxies orbiting the Milky Way. But dwarf galaxy Leo I has shown evidence of a supermassive black hole at its center, comparable in mass to the black hole at the center of the Milky Way.

Image credit: Markus Horn
All Sky Moon Shadow (2024-04-27)

If the Sun is up but the sky is dark and the horizon is bright all around, you might be standing in the Moon's shadow during a total eclipse of the Sun. In fact, the all-sky Moon shadow shown in this composited panoramic view was captured from a farm near Shirley, Arkansas, planet Earth. The exposures were made under clear skies during the April 8 total solar eclipse. For that location near the center line of the Moon's shadow track, totality lasted over 4 minutes. Along with the solar corona surrounding the silhouette of the Moon planets and stars were visible during the total eclipse phase. Easiest to see here are bright planets Venus and Jupiter, to the lower right and upper left of the eclipsed Sun.

Image credit: Tunc Tezel
Rings Around the Ring Nebula (2024-04-28)

The Ring Nebula (M57) is more complicated than it appears through a small telescope.  The easily visible central ring is about one light-year across, but this remarkably deep exposure - a collaborative effort combining data from three different large telescopes - explores the looping filaments of glowing gas extending much farther from the nebula's central star. This composite image includes red light emitted by hydrogen as well as visible and infrared light. The Ring Nebula is an elongated planetary nebula, a type of nebula created when a Sun-like star evolves to throw off its outer atmosphere and become a white dwarf star.  The Ring Nebula is about 2,500 light-years away toward the musical constellation Lyra.   Your Sky Surprise: What picture did APOD feature on your birthday? (post 1995)

Image credit: Robert Gendler
Comet, Planet, Moon (2024-04-29)

Three bright objects satisfied seasoned stargazers of the western sky just after sunset earlier this month. The most familiar was the Moon, seen on the upper left in a crescent phase. The rest of the Moon was faintly visible by sunlight first reflected by the Earth. The bright planet Jupiter, the largest planet in the Solar System, is seen to the upper left.  Most unusual was Comet 12P/Pons-Brooks, below the Moon and showing a stubby dust tail on the right but an impressive ion tail extending upwards.  The featured image, a composite of several images taken consecutively at the same location and with the same camera, was taken near the village of Llers, in Spain's Girona province.  Comet Pons-Brooks passed its closest to the Sun last week and is now dimming as it moves into southern skies and returns to the outer Solar System.   Almost Hyperspace: Random APOD Generator

Image credit: Juan Carlos Casado
GK Per: Nova and Planetary Nebula (2024-04-30)

The star system GK Per is known to be associated with only two of the three nebulas pictured.  At 1500 light years distant, Nova Persei 1901 (GK Persei) was the second closest nova yet recorded. At the very center is a white dwarf star, the surviving core of a former Sun-like star. It is surrounded by the circular Firework nebula, gas that was ejected by a thermonuclear explosion on the white dwarf's surface -- a nova -- as recorded in 1901. The red glowing gas surrounding the Firework nebula is the atmosphere that used to surround the central star. This gas was expelled before the nova and appears as a diffuse planetary nebula.  The faint gray gas running across is interstellar cirrus that seems to be just passing through coincidently. In 1901, GK Per's nova became brighter than Betelgeuse. Similarly, star system T CrB is expected to erupt in a nova later this year, but we don't know exactly when nor how bright it will become.

Image credit: Deep Sky Collective
IC 1795: The Fishhead Nebula (2024-05-01)

To some, this nebula looks like the head of a fish. However, this colorful cosmic portrait really features glowing gas and obscuring dust clouds in IC 1795, a star forming region in the northern constellation Cassiopeia. The nebula's colors were created by adopting the Hubble color palette for mapping narrowband emissions from oxygen, hydrogen, and sulfur atoms to blue, green and red colors, and further blending the data with images of the region recorded through broadband filters. Not far on the sky from the famous Double Star Cluster in Perseus, IC 1795 is itself located next to IC 1805, the Heart Nebula, as part of a complex of star forming regions that lie at the edge of a large molecular cloud. Located just over 6,000 light-years away, the larger star forming complex sprawls along the Perseus spiral arm of our Milky Way Galaxy. At that distance, IC 1795 would span about 70 light-years across.   Open Science: Browse 3,300+ codes in the Astrophysics Source Code Library

Image credit: Roberto Colombari & 
Mauro Narduzzi
M100: A Grand Design Spiral Galaxy (2024-05-02)

Majestic on a truly cosmic scale, M100 is appropriately known as a grand design spiral galaxy.  The large galaxy of over 100 billion stars has well-defined spiral arms, similar to our own Milky Way.  One of the brightest members of the Virgo Cluster of galaxies, M100, also known as NGC 4321 is 56 million light-years distant toward the well-groomed constellation Coma Berenices.  In this telescopic image, the face-on grand design spiral shares a nearly 1 degree wide field-of-view with slightly less conspicuous edge-on spiral NGC 4312 (at upper right). The 21 hour long equivalent exposure from a dark sky site near Flagstaff, Arizona, planet Earth, reveals M100's bright blue star clusters and intricate winding dust lanes which are hallmarks of this class of galaxies.  Measurements of variable stars in M100 have played an important role in determining the size and age of the Universe.

Image credit: Drew Evans
Temperatures on Exoplanet WASP-43b (2024-05-03)

A mere 280 light-years from Earth, tidally locked, Jupiter-sized exoplanet WASP-43b orbits its parent star once every 0.8 Earth days. That puts it about 2 million kilometers (less than 1/25th the orbital distance of Mercury) from a small, cool sun. Still, on a dayside always facing its parent star, temperatures approach a torrid 2,500 degrees F as measured at infrared wavelengths by the MIRI instrument on board the James Webb Space Telescope. In this illustration of the hot exoplanet's orbit, Webb measurements also show nightside temperatures remain above 1,000 degrees F. That suggests that strong equatorial winds circulate the dayside atmospheric gases to the nightside before they can completely cool off. Exoplanet WASP-43b is now formally known as Astrolábos, and its K-type parent star has been christened Gnomon. Webb's infrared spectra indicate water vapor is present on the nightside as well as the dayside of the planet, providing information about cloud cover on Astrolábos.
3 ATs (2024-05-04)

Despite their resemblance to R2D2, these three are not the droids you're looking for. Instead, the enclosures house 1.8 meter Auxiliary Telescopes (ATs) at Paranal Observatory in the Atacama Desert region of Chile. The ATs are designed to be used for interferometry, a technique for achieving extremely high resolution observations, in concert with the observatory's 8 meter Very Large Telescope units. A total of four ATs are operational, each fitted with a transporter that moves the telescope along a track allowing different arrays with the large unit telescopes. To work as an interferometer, the light from each telescope is brought to a common focal point by a system of mirrors in underground tunnels. Above these three ATs, the Large and Small Magellanic Clouds are the far, far away satellite galaxies of our own Milky Way. In the clear and otherwise dark southern skies, planet Earth's greenish atmospheric airglow stretches faintly along the horizon.

Image credit: Yuri Beletsky
A Black Hole Disrupts a Passing Star (2024-05-05)

What happens to a star that goes near a black hole? If the star directly impacts a massive black hole, then the star falls in completely -- and everything vanishes. More likely, though, the star goes close enough to have the black hole's gravity pull away its outer layers, or disrupt, the star. Then, most of the star's gas does not fall into the black hole.  These stellar tidal disruption events can be as bright as a supernova, and an increasing amount of them are being discovered by automated sky surveys. In the featured artist's illustration, a star has just passed a massive black hole and sheds gas that continues to orbit.  The inner edge of a disk of gas and dust surrounding the black hole is heated by the disruption event and may glow long after the star  is gone.    Hole New Worlds: It's Black Hole Week at NASA!
A Total Solar Eclipse from Sliver to Ring (2024-05-06)

This is how the Sun disappeared from the daytime sky last month. The featured time-lapse video was created from stills taken from Mountain View, Arkansas, USA on 2024 April 8. First, a small sliver of a normally spotted Sun went strangely dark. Within a few minutes, much of the background Sun was hidden behind the advancing foreground Moon. Within an hour, the only rays from the Sun passing the Moon appeared like a diamond ring. During totality, most of the surrounding sky went dark, making the bright pink prominences around the Sun's edge stand out, and making the amazing corona appear to spread into the surrounding sky.  The central view of the corona shows an accumulation of frames taken during complete totality. As the video ends, just a few minutes later, another diamond ring appeared -- this time on the other side of the Moon. Within the next hour, the sky returned to normal.   Celebrate the Voids: It's Black Hole Week at NASA!

Image credit: Reinhold Wittich;
Music: Sunrise from 
Also sprach Zarathusra 
(R. Strauss) 
by Sascha Ende
Black Hole Accreting with Jet (2024-05-07)

What happens when a black hole devours a star?  Many details remain unknown, but observations are providing new clues. In 2014, a powerful explosion was recorded by the ground-based robotic telescopes of the All Sky Automated Survey for SuperNovae (Project ASAS-SN), with followed-up observations by instruments including NASA's Earth-orbiting Swift satellite. Computer modeling of these emissions fit a star being ripped apart by a distant supermassive black hole.  The results of such a collision are portrayed in the featured artistic illustration. The black hole itself is a depicted as a tiny black dot in the center. As matter falls toward the hole, it collides with other matter and heats up. Surrounding the black hole is an accretion disk of hot matter that used to be the star, with a jet emanating from the black hole's spin axis.   Fall towards eternity: It's Black Hole Week at NASA!
Visualization: A Black Hole Accretion Disk (2024-05-08)

What would it look like to circle a black hole? If the black hole was surrounded by a swirling disk of glowing and accreting gas, then the great gravity of the black hole would deflect light emitted by the disk to make it look very unusual. The featured animated video gives a visualization. The video starts with you, the observer, looking toward the black hole from just above the plane of the accretion disk.  Surrounding the central black hole is a thin circular image of the orbiting disk that marks the position of the photon sphere -- inside of which lies the black hole's event horizon.  Toward the left, parts of the large main image of the disk appear brighter as they move toward you. As the video continues, you loop over the black hole, soon looking down from the top, then passing through the disk plane on the far side, then returning to your original vantage point. The accretion disk does some interesting image inversions -- but never appears flat. Visualizations such as this are particularly relevant today as black holes are being imaged in unprecedented detail by the Event Horizon Telescope.   Singularity Impressive: It's Black Hole Week at NASA!
The Galaxy, the Jet, and a Famous Black Hole (2024-05-09)

Bright elliptical galaxy Messier 87 (M87) is home to the supermassive black hole captured in 2017 by planet Earth's Event Horizon Telescope in the first ever image of a black hole. Giant of the Virgo galaxy cluster about 55 million light-years away, M87 is rendered in blue hues in this infrared image from the Spitzer Space telescope.  Though M87 appears mostly featureless and cloud-like, the Spitzer image does record details of relativistic jets blasting from the galaxy's central region. Shown in the inset at top right, the jets themselves span thousands of light-years. The brighter jet seen on the right is approaching and close to our line of sight. Opposite, the shock created by the otherwise unseen receding jet lights up a fainter arc of material. Inset at bottom right, the historic black hole image is shown in context at the center of giant galaxy, between the relativistic jets. Completely unresolved in the Spitzer image, the supermassive black hole surrounded by infalling material is the source of enormous energy driving the relativistic jets from the center of active galaxy M87. The Event Horizon Telescope image of M87 has been enhanced to reveal a sharper view of the famous supermassive black hole.   It's inescapable: Black Hole Week at NASA!
Simulation: Two Black Holes Merge (2024-05-10)

Relax and watch two black holes merge. Inspired by the first direct detection of gravitational waves in 2015, this simulation plays in slow motion but would take about one third of a second if run in real time. Set on a cosmic stage, the black holes are posed in front of stars, gas, and dust. Their extreme gravity lenses the light from behind them into Einstein rings as they spiral closer and finally merge into one. The otherwise invisible gravitational waves generated as the massive objects rapidly coalesce cause the visible image to ripple and slosh both inside and outside the Einstein rings even after the black holes have merged. Dubbed GW150914, the gravitational waves detected by LIGO are consistent with the merger of 36 and 31 solar mass black holes at a distance of 1.3 billion light-years. The final, single black hole has 63 times the mass of the Sun, with the remaining 3 solar masses converted into energy radiated in gravitational waves.   Today's Event Horizon: It's Black Hole Week at NASA!
AR 3664: Giant Sunspot Group (2024-05-11)

Right now, one of the largest sunspot groups in recent history is crossing the Sun. Active Region 3664 is not only big -- it's violent, throwing off clouds of particles into the Solar System. Some of these CMEs are already impacting the Earth, and others might follow.  At the extreme, these solar storms could cause some Earth-orbiting satellites to malfunction, the Earth's atmosphere to slightly distort, and electrical power grids to surge. When impacting Earth's upper atmosphere, these particles can produce beautiful auroras, with some auroras already being reported unusually far south.  Pictured here, AR3664 and its dark sunspots were captured yesterday in visible light from Rome, Italy. The AR3664 sunspot group is so large that it is visible just with glasses designed to view last month's total solar eclipse.  This weekend, skygazing enthusiasts will be keenly watching the night skies all over the globe for bright and unusual auroras.   Gallery: Active Region 3664 on the Sun and Associated Aurora

Image credit: Franco Fantasia & 
Guiseppe Conzo 
(Gruppo Astrofili Palidoro)