How do black holes create X-rays? Answering this long-standing question was significantly advanced recently with data taken by NASA’s IXPE satellite. X-rays cannot exit a black hole, but they can be created in the energetic environment nearby, in particular by a jet of particles moving outward. By observing X-ray light arriving from near the supermassive black hole at the center of galaxy BL Lac, called a blazar, it was discovered that these X-rays lacked significant polarization, which is expected when created more by energetic electrons than protons. In the featured artistic illustration, a powerful jet is depicted emanating from an orange-colored accretion disk circling the black hole. Understanding highly energetic processes across the universe helps humanity to understand similarprocesses that occur on or near our Earth.

https://apod.nasa.gov/apod/ap250509.html ( May 09, 2025)

M1: The Incredible Expanding Crab

Cataloged as M1, the Crab Nebula is the first on Charles Messier's famous list of things which are not comets. In fact, the Crab Nebula is now known to be a supernova remnant, an expanding cloud of debris from the death explosion of a massive star. The violent birth of the Crab was witnessed by astronomers in the year 1054. Roughly 10 light-years across, the nebula is still expanding at a rate of about 1,500 kilometers per second. You can see the expansion by comparing these sharp images from the Hubble Space Telescope and James Webb Space Telescope. The Crab's dynamic, fragmented filaments were captured in visible light by Hubble in 2005 and Webb in infrared light in 2023. This cosmic crustacean lies about 6,500 light-years away in the constellation Taurus.

https://apod.nasa.gov/apod/ap250508.html ( May 08, 2025)

In the upper left corner, surrounded by blue arms and dotted with red nebulas, is spiral galaxy M81. In the lower right corner, marked by a light central line and surrounded by red glowing gas, is irregular galaxy M82. This stunning vista shows these two mammoth galaxies locked in gravitational combat, as they have been for the past billion years. The gravity from each galaxy dramatically affects the other during each hundred-million-year pass. Last go-round, M82's gravity likely raised density waves rippling around M81, resulting in the richness of M81's spiral arms. But M81 left M82 with violent star forming regions and colliding gas clouds so energetic the galaxy glows in X-rays. This big battle is seen from Earth through the faint glow of an Integrated Flux Nebula, a little studied complex of diffuse gas and dust clouds in our Milky Way Galaxy. In a few billion years, only one galaxy will remain.

https://apod.nasa.gov/apod/ap250507.html ( May 07, 2025)

If one black hole looks strange, what about two? Light rays from accretion disks around a pair of orbiting supermassive black holes make their way through the warped space-time produced by extreme gravity in this detailed computer visualization. The simulated accretion disks have been given different false color schemes, red for the disk surrounding a 200-million-solar-mass black hole, and blue for the disk surrounding a 100-million-solar-mass black hole. For these masses, though, both accretion disks would actually emit most of their light in the ultraviolet. The video allows us to see both sides of each black hole at the same time. Red and blue light originating from both black holes can be seen in the innermost ring of light, called the photon sphere, near their event horizons. In the past decade, gravitational waves from black hole collisions have actually been detected, although the coalescence of supermassive black holes remains undiscovered.

https://apod.nasa.gov/apod/ap250506.html ( May 06, 2025)

What’s causing those lines? Objects in the sky sometimes appear reflected as lines across water — but why? If the water’s surface is smooth, then reflected objects would appear similarly -- as spots. But if the water is choppy, then there are many places where light from the object can reflect off the water and still come to you -- and so together form, typically, a line. The same effect is frequently seen for the Sun just before sunset and just after sunrise. Pictured about 10 days ago in Ibiza, Spain, images of the setting Moon, Venus (top), and Saturn (right, faint) were captured both directly and in line-reflected forms from the Mediterranean Sea. The other bright object on the right with a water-reflected line is a beacon on a rock to warn passing boats.

https://apod.nasa.gov/apod/ap250505.html ( May 05, 2025)

How fast can a black hole spin? If any object made of regular matter spins too fast -- it breaks apart. But a black hole might not be able to break apart -- and its maximum spin rate is really unknown. Theorists usually model rapidly rotating black holes with the Kerr solution to Einstein's General Theory of Relativity, which predicts several amazing and unusual things. Perhaps its most easily testable prediction, though, is that matter entering a maximally rotating black hole should be last seen orbiting at near the speed of light, as seen from far away. This prediction was tested by NASA's NuSTAR and ESA's XMM satellites by observing the supermassive black hole at the center of spiral galaxy NGC 1365. The near light-speed limit was confirmed by measuring the heating and spectral line broadening of nuclear emissions at the inner edge of the surrounding accretion disk. Pictured here is an artist's illustration depicting an accretion disk of normal matter swirling around a black hole, with a jet emanating from the top. Since matter randomly falling into the black hole should not spin up a black hole this much, the NuSTAR and XMM measurements also validate the existence of the surrounding accretion disk.

https://apod.nasa.gov/apod/ap250504.html ( May 04, 2025)

Titan: Moon over Saturn

Like Earth's moon, Saturn's largest moon Titan is locked in synchronous rotation with its planet. This mosaic of images recorded by the Cassini spacecraft in May of 2012 shows its anti-Saturn side, the side always facing away from the ringed gas giant. The only moon in the solar system with a dense atmosphere, Titan is the only solar system world besides Earth known to have standing bodies of liquid on its surface and an earthlike cycle of liquid rain and evaporation. Its high altitude layer of atmospheric haze is evident in the Cassini view of the 5,000 kilometer diameter moon over Saturn's rings and cloud tops. Near center is the dark dune-filled region known as Shangri-La. The Cassini-delivered Huygens probe rests below and left of center, after the most distant landing for a spacecraft from Earth.

https://apod.nasa.gov/apod/ap250503.html ( May 03, 2025)

Young Star Cluster NGC 346

The most massive young star cluster in the Small Magellanic Cloud is NGC 346, embedded in our small satellite galaxy's largest star forming region some 210,000 light-years distant. Of course the massive stars of NGC 346 are short lived, but very energetic. Their winds and radiation sculpt the edges of the region's dusty molecular cloud triggering star-formation within. The star forming region also appears to contain a large population of infant stars. A mere 3 to 5 million years old and not yet burning hydrogen in their cores, the infant stars are strewn about the embedded star cluster. This spectacular infrared view of NGC 346 is from the James Webb Space Telescope's NIRcam. Emission from atomic hydrogen ionized by the massive stars' energetic radiation as well as molecular hydrogen and dust in the star-forming molecular cloud is detailed in pink and orange hues. Webb's sharp image of the young star-forming region spans 240 light-years at the distance of the Small Magellanic Cloud.

https://apod.nasa.gov/apod/ap250502.html ( May 02, 2025)

MESSENGER s Last Day on Mercury

The first to orbit inner planet Mercury, the MESSENGER spacecraft came to rest on this region of Mercury's surface on April 30, 2015. Constructed from MESSENGER image and laser altimeter data, the projected scene looks north over the northeastern rim of the broad, lava filled Shakespeare basin. The large, 48 kilometer (30 mile) wide crater Janacek is near the upper left edge. Terrain height is color coded with red regions about 3 kilometers above blue ones. MESSENGER'S final orbit was predicted to end near the center, with the spacecraft impacting the surface at nearly 4 kilometers per second (over 8,700 miles per hour) and creating a new crater about 16 meters (52 feet) in diameter. The impact on the far side of Mercury was not observed by telescopes, but confirmed when no signal was detected from the spacecraft given time to emerge from behind the planet. Launched in 2004, the MErcury Surface, Space ENvironment, GEochemisty and Ranging spacecraft completed over 4,000 orbits after reaching the Solar System's innermost planet in 2011.

https://apod.nasa.gov/apod/ap250501.html ( May 01, 2025)

Sometimes, the sky itself seems to smile. A few days ago, visible over much of the world, an unusual superposition of our Moon with the planets Venus and Saturn created just such an iconic facial expression. Specifically, a crescent Moon appeared to make a happy face on the night sky when paired with seemingly nearby planets. Pictured is the scene as it appeared over Zacatecas, México, with distinctive Bufa Hill in the foreground. On the far right and farthest in the distance is the planet Saturn. Significantly closer and visible to Saturn's upper left is Venus, the brightest planet on the sky. Just above the central horizon is Earth's Moon in a waning crescent phase. To create this gigantic icon, the crescent moon phase must be smiling in the correct direction.

https://apod.nasa.gov/apod/ap250430.html ( April 30, 2025)

Where are Saturn's ears? Galileo is credited, in 1610, as the first person to see Saturn's rings. Testing out Lipperhey's recently co-invented telescope, Galileo did not know what they were and so called them "ears". The mystery deepened in 1612, when Saturn's ears mysteriously disappeared. Today we know exactly what happened: from the perspective of the Earth, Saturn's rings had become too thin to see. The same drama plays out every 15 years because Saturn, like Earth, undergoes tilt-driven seasons. This means that as Saturn goes around the Sun, its equator and rings can tilt noticeably toward the Sun and inner Solar System, making them easily visible, but from other orbital locations will appear almost not at all. The featured picture from Brasilia, Brazil shows a modern version of this sequence: the top ring-dominated image was taken in 2020, while the bottom ring-obscure image taken earlier in 2025.

https://apod.nasa.gov/apod/ap250429.html ( April 29, 2025)

This cosmic skyscape features glowing gas and dark dust clouds alongside the young stars of NGC 3572. A beautiful emission nebula and star cluster, it sails far southern skies within the nautical constellation Carina. Stars from NGC 3572 are toward top center in the telescopic frame that would measure about 100 light-years across at the cluster's estimated distance of 9,000 light-years. The visible interstellar gas and dust, shown in colors of the Hubble palette, is part of the star cluster's natal molecular cloud, itself cataloged as Gum 37. Dense streamers of material within the nebula, eroded by stellar winds and radiation, clearly trail away from the energetic young stars. They are likely sites of ongoing star formation with shapes reminiscent of the Tadpoles of IC 410 -- better known to northern skygazers. In the coming tens to hundreds of millions of years, gas and stars in the cluster will be dispersed though, by gravitational tides and by violent supernova explosions that end the short lives of the massive cluster stars.

https://apod.nasa.gov/apod/ap250428.html ( April 28, 2025)

What is creating the strange texture of IC 418? Dubbed the Spirograph Nebula for its resemblance to drawings from a cyclical drawing tool, planetary nebula IC 418 shows patterns that are not well understood. Perhaps they are related to chaotic winds from the variable central star, which changes brightness unpredictably in just a few hours. By contrast, evidence indicates that only a few million years ago, IC 418 was probably a well-understood star similar to our Sun. Only a few thousand years ago, IC 418 was probably a common red giant star. Since running out of nuclear fuel, though, the outer envelope has begun expanding outward leaving a hot remnant core destined to become a white-dwarf star, visible in the image center. The light from the central core excites surrounding atoms in the nebula causing them to glow. IC 418 lies about 2000 light-years away and spans 0.3 light-years across. This false-color image taken from the Hubble Space Telescope reveals the unusual details.

https://apod.nasa.gov/apod/ap250427.html ( April 27, 2025)

Barred Spiral Galaxy NGC 5335

This stunning portrait of NGC 5335 was captured by the Hubble Space Telescope. Some 170,000 light-years across and over 200 million light-years away toward the constellation Virgo, the magnificent spiral galaxy is seen face-on in Hubble's view. Within the galactic disk, loose streamers of star forming regions lie along the galaxy's flocculent spiral arms. But the most striking feature of NGC 5335 is its prominent central bar. Seen in about 30 percent of galaxies, including our Milky Way, bar structures are understood to channel material inward toward the galactic center, fueling star formation. Of course, distant background galaxies are easy to spot, scattered around the sharp Hubble image. Launched in 1990, Hubble is now celebrating its 35th year exploring the cosmos from orbit around planet Earth.

https://apod.nasa.gov/apod/ap250426.html ( April 26, 2025)

Asteroid Donaldjohanson

Main belt asteroid52246 Donaldjohanson is about 8 kilometers long and 3.5 kilometers across. On April 20, this sharp close-up of the asteroid was captured at a distance of about 1100 kilometers by the Lucy spacecraft's long range camera during its second asteroid encounter. Named after American paleoanthropologist Donald Johanson, discoverer of the Lucy hominid fossil, the elongated asteroid was likely formed about 150 million years ago from a gentle collision of two smaller bodies creating its characteristic contact binary shape. Launched in October of 2021, the Lucy spacecraft will continue its travels through the main asteroid belt in 2025, but is on its way to explore Jupiter's swarm of Trojan asteroids. Lucy is expected to encounter its first Trojan asteroid target, 3548 Eurybates, in August 2027.

https://apod.nasa.gov/apod/ap250425.html ( April 25, 2025)

NGC 6164: A Dragon s Egg

Beautiful emission nebula NGC 6164 was created by a rare, hot, luminous O-type star, some 40 times as massive as the Sun. Seen at the center of the cosmic cloud, the star is a mere 3 to 4 million years old. In another three to four million years the massive star will end its life in a supernova explosion. Spanning around 4 light-years, the nebula itself has a bipolar symmetry. That makes it similar in appearance to more common and familiar planetary nebulae - the gaseous shrouds surrounding dying sun-like stars. Also like many planetary nebulae, NGC 6164 has been found to have an extensive, faint halo, revealed in this deep image of the region. Expanding into the surrounding interstellar medium, the material in the halo is likely from an earlier active phase of the O star. This gorgeous telescopic view is a composite of extensive narrow-band image data, highlighting glowing atomic hydrogen gas in red and oxygen in greenish hues, with broad-band data for the surrounding starfield. Also known as the Dragon's Egg nebula, NGC 6164 is 4,200 light-years away in the right-angled southern constellation of Norma.

https://apod.nasa.gov/apod/ap250424.html ( April 24, 2025)

This surprising sky has almost everything. First, slanting down from the upper left and far in the distance is the central band of our Milky Way Galaxy. More modestly, slanting down from the upper right and high in Earth's atmosphere is a bright meteor. The dim band of light across the central diagonal is zodiacal light: sunlight reflected from dust in the inner Solar System. The green glow on the far right is aurora high in Earth's atmosphere. The bright zigzagging bright line near the bottom is just a light that was held by the scene-planning astrophotographer. This "almost everything" sky was captured over rocks on Castle Hill, New Zealand late last month. The featured finished frame is a combination of 10 exposures all taken with the same camera and from the same location. But what about the astrophotographer himself? He's pictured too -- can you find him?

https://apod.nasa.gov/apod/ap250423.html ( April 23, 2025)

What's different about this Moon? It's the terminators. In the featured image, you can't directly see any terminator -- the line that divides the light of day from the dark of night. That's because the featured image is a digital composite of many near-terminator lunar strips over a full Moon. Terminator regions show the longest and most prominent shadows -- shadows which, by their contrast and length, allow a flat photograph to appear three-dimensional. The overlay images were taken over two weeks in early April. Many of the Moon's craters stand out because of the shadows they all cast to the right. The image shows in graphic detail that the darker regions known as maria are not just darker than the rest of the Moon -- they are also flatter.

https://apod.nasa.gov/apod/ap250422.html ( April 22, 2025)

Is this one galaxy or two? Although it looks like one, the answer is two. One path to this happening is when a small galaxy collides with a larger galaxy and ends up in the center. But in the featured image, something more rare is going on. Here, the central light-colored elliptical galaxy is much closer than the blue and red-colored spiral galaxy that surrounds it. This can happen when near and far galaxies are exactly aligned, causing the gravity of the near galaxy to pull the light from the far galaxy around it in an effect called gravitational lensing. The featured galaxy double was taken by the Webb Space Telescope and shows a complete Einstein ring, with great detail visible for both galaxies. Galaxy lenses like this can reveal new information about the mass distribution of the foreground lens and the light distribution of the background source.

https://apod.nasa.gov/apod/ap250421.html ( April 21, 2025)

The Great Nebula in Orion is a colorful place. Visible to the unaided eye, it appears as a small fuzzy patch in the constellation of Orion. Long exposure, multi-wavelength images like this, however, show the Orion Nebula to be a busy neighborhood of young stars, hot gas, and dark dust. This digital composite features not only three colors of visible light but four colors of infrared light taken by NASA's orbiting Spitzer Space Telescope as well. The power behind much of the Orion Nebula (M42) is the Trapezium - four of the brightest stars in the nebula. Many of the filamentary structures visible are actually shock waves - fronts where fast moving material encounters slow moving gas. The Orion Nebula spans about 40 light years and is located about 1500 light years away in the same spiral arm of our Galaxy as the Sun.

https://apod.nasa.gov/apod/ap250420.html ( April 20, 2025)

Painting with Jupiter

In digital brush strokes, Jupiter's signature atmospheric bands and vortices were used to form this interplanetary post-impressionist work of art. The creative image from citizen scientist Rick Lundh uses data from the Juno spacecraft's JunoCam. To paint on the digital canvas, a JunoCam image with contrasting light and dark tones was chosen for processing and an oil-painting software filter applied. The image data was captured during perijove 10. That was Juno's December 16, 2017 close encounter with the solar system's ruling gas giant. At the time the spacecraft was cruising about 13,000 kilometers above northern Jovian cloud tops. Now in an extended mission, Juno has explored Jupiter and its moons since entering orbit around Jupiter in July of 2016.

https://apod.nasa.gov/apod/ap250419.html ( April 19, 2025)

Comet C/2025 F2 SWAN

In late March, the comet now designated C/2025 F2 SWAN was found independently by citizen scientists Vladimir Bezugly, Michael Mattiazzo, and Rob Matson while examining publicly available image data from the Solar Wind ANisotropies (SWAN) camera on the sun-staring SOHO spacecraft. Comet SWAN's coma, its greenish color a signature of diatomic carbon molecules fluorescing in sunlight, is at lower left in this telescopic image. SWAN's faint ion tail extends nearly two degrees toward the upper right across the field of view. The interplanetary scene was captured in clear but moonlit skies from June Lake, California on April 14. Seen against background of stars toward the constellation Andromeda, the comet was then some 10 light-minutes from our fair planet. Now a target for binoculars and small telescopes in northern hemisphere morning skies this comet SWAN is headed for a perihelion, its closest approach to the Sun, on May 1. That will bring this visitor from the distant Oort cloud almost as close to the Sun as the orbit of inner planet Mercury.

https://apod.nasa.gov/apod/ap250418.html ( April 18, 2025)

Virgo Cluster Galaxies

Galaxies of the Virgo Cluster are scattered across this nearly 4 degree wide telescopic field of view. About 50 million light-years distant, the Virgo Cluster is the closest large galaxy cluster to our own local galaxy group. Prominent here are Virgo's bright elliptical galaxies from the Messier catalog, M87 at bottom left, and M86 and M84 near center right. M86 and M84 are recognized as part of Markarian's Chain, the visually striking line-up of galaxies on the that runs through the upper portion of this frame. Near the middle of the chain lies an intriguing interacting pair of galaxies, NGC 4438 and NGC 4435, known to some as Markarian's Eyes. Still, giant elliptical galaxy M87 dominates the Virgo cluster. It's the home of a super massive black hole, the first black hole ever imaged by planet Earth's Event Horizon Telescope.

https://apod.nasa.gov/apod/ap250417.html ( April 17, 2025)

What created the unusual halo around the Cat's Eye Nebula? No one is sure. What is sure is that the Cat's Eye Nebula (NGC 6543) is one of the best known planetary nebulae on the sky. Although haunting symmetries are seen in the bright central region, this image was taken to feature its intricately structured outer halo, which spans over three light-years across. Planetary nebulae have long been appreciated as a final phase in the life of a Sun-like star. Only recently however, have some planetaries been found to have expansive halos, likely formed from material shrugged off during earlier puzzling episodes in the star's evolution. While the planetary nebula phase is thought to last for around 10,000 years, astronomers estimate the age of the outer filamentary portions of the Cat's Eye Nebula's halo to be 50,000 to 90,000 years.

https://apod.nasa.gov/apod/ap250416.html ( April 16, 2025)

What happens when a star runs out of nuclear fuel? For stars like our Sun, the center condenses into a white dwarf while the outer atmosphere is expelled into space to appear as a planetary nebula. The expelled outer atmosphere of planetary nebula NGC 1514 appears to be a jumble of bubbles -- when seen in visible light. But the view from the James Webb Space Telescope in infrared, as featured here, confirms a different story: in this light the nebula shows a distinct hourglass shape, which is interpreted as a cylinder seen along a diagonal. If you look closely at the center of the nebula, you can also see a bright central star that is part of a binary system. More observations might better reveal how this nebula is evolving and how the central stars are working together to produce the interesting cylinder and bubbles observed.

https://apod.nasa.gov/apod/ap250415.html ( April 15, 2025)

What's happening at the center of our galaxy? It's hard to tell with optical telescopes since visible light is blocked by intervening interstellar dust. In other bands of light, though, such as radio, the galactic center can be imaged and shows itself to be quite an interesting and active place. The featured picture shows an image of our Milky Way's center by the MeerKAT array of 64 radio dishes in South Africa. Spanning four times the angular size of the Moon (2 degrees), the image is impressively vast, deep, and detailed. Many known sources are shown in clear detail, including many with a prefix of Sgr, since the galactic center is in the direction of the constellation Sagittarius. In our galaxy's center lies Sgr A, found here in the image center, which houses the Milky Way's central supermassive black hole. Other sources in the image are not as well understood, including the Arc, just to the left of Sgr A, and numerous filamentary threads. The inset image shows a small patch recently imaged in infrared light with the James Webb Space Telescope to investigate the effects of magnetic fields on star formation.

https://apod.nasa.gov/apod/ap250414.html ( April 14, 2025)

What created this unusual hole in Mars? Actually, there are numerous holes pictured in this Swiss cheese-like landscape, with all-but-one of them showing a dusty, dark, Martian terrain beneath evaporating, light, carbon dioxide ice. The most unusual hole is on the upper right, spans about 100 meters, and seems to punch through to a lower level. Why this hole exists and why it is surrounded by a circular crater remains a topic of speculation, although a leading hypothesis is that it was created by a meteor impact. Holes such as this are of particular interest because they might be portals to lower levels that extend into expansive underground caves. If so, these naturally occurring tunnels are relatively protected from the harsh surface of Mars, making them relatively good candidates to contain Martian life. These pits are therefore also prime targets for possible future spacecraft, robots, and even human interplanetary explorers.

https://apod.nasa.gov/apod/ap250413.html ( April 13, 2025)

Moon Near the Edge

Most of us watch the Moon at night. But the Moon spends nearly as many daylight hours above our horizon, though in bright daytime skies the lunar disk looks pale and can be a little harder to see. Of course in daytime skies the Moon also appears to cycle through its phases, shining by reflected sunlight as it orbits our fair planet. For daytime moonwatchers, the Moon is probably easier to spot when the visible sunlit portion of the lunar disk is large and waxing following first quarter or waning approaching its third quarter phase. And though it might look unusual, a daytime moon is often seen even in urban skies. Captured here in a telephoto snapshot taken on March 12, a waxing daytime Moon is aligned near the edge of a popular observation deck that overlooks New York City's borough of Manahattan.

https://apod.nasa.gov/apod/ap250412.html ( April 12, 2025)

The ISS Meets Venus

Made with a telescope shaded from bright sunlight by an umbrella, on April 5 a well-planned video captured a crescent Venus shining in clear daytime skies from Shoreline, Washington, USA at 11:57AM Pacific Time. It also caught the International Space Station in this single video frame. In close conjunction with the bright planet, the faint outline of the orbital outpost seen at a range of about 400 kilometers appears to be similar in size to the slender planetary crescent. Of course the ISS is much smaller than Venus. Now appearing as planet Earth's brilliant morning star and climbing above the eastern horizon in predawn skies, inner planet Venus was nearly 45 million kilometers from Shoreline.

https://apod.nasa.gov/apod/ap250411.html ( April 11, 2025)

38 Hours in the M81 Group

From a garden on planet Earth, 38 hours of exposure with a camera and small telescope produced this cosmic photo of the M81 galaxy group. In fact, the group's dominant galaxy M81 is near the center of the frame sporting grand spiral arms and a bright yellow core. Also known as Bode's galaxy, M81 itself spans some 100,000 light-years. Near the top is cigar-shaped irregular galaxy M82. The pair have been locked in gravitational combat for a billion years. Gravity from each galaxy has profoundly affected the other during a series of cosmic close encounters. Their last go-round lasted about 100 million years and likely raised density waves rippling around M81, resulting in massive star forming regions arrayed along M81's spiral arms. M82 was left with violent star forming regions too, and colliding gas clouds so energetic that the galaxy glows in X-rays. In the next few billion years, their continuing gravitational encounters will result in a merger, and a single galaxy will remain. Another group member, NGC 3077 is below and left of the large spiral M81. Far far away, about 12 million light-years distant the M81 group galaxies are seen toward the northern constellation Ursa Major (the Great Bear). But in the closer foreground the wide-field image is filled with integrated flux nebulae whose faint, dusty interstellar clouds reflect starlight above the plane of our own Milky Way galaxy.

https://apod.nasa.gov/apod/ap250410.html ( April 10, 2025)

What's at the tip of this interstellar jet? First let's consider the jet: it is being expelled by a star system just forming and is cataloged as Herbig-Haro 49 (HH 49). The star system expelling this jet is not visible -- it is off to the lower right. The complex conical structure featured in this infrared image by the James Webb Space Telescope also includes another jet cataloged as HH 50. The fast jet particles impact the surrounding interstellar gas and form shock waves that glow prominently in infrared light -- shown here as reddish-brown ridges. This JWST image also resolved the mystery of the unusual object at HH 49's tip: it is a spiral galaxy far in the distance. The blue center is therefore not one star but many, and the surrounding circular rings are actually spiral arms.

https://apod.nasa.gov/apod/ap250409.html ( April 09, 2025)

Sometimes, the Moon visits the Pleiades. Technically, this means that the orbit of our Moon takes it directly in front of the famous Pleiades star cluster, which is far in the distance. The technical term for the event is an occultation, and the Moon is famous for its rare occultations ofallplanets and several well-known bright stars. The Moon's tilted and precessing orbit makes its occultations of the Seven Sisters star cluster bunchy, with the current epoch starting in 2023 continuing monthly until 2029. After that, though, the next occultation won't occur until 2042. Taken from Cantabria, Spain on April 1, the featured image is a composite where previous exposures of the Pleiades from the same camera and location were digitally added to the last image to bring up the star cluster's iconic blue glow.

https://apod.nasa.gov/apod/ap250408.html ( April 08, 2025)

How much mass do flocculent spirals hide? The featured image of flocculent spiral galaxy NGC 4414 was taken with the Hubble Space Telescope to help answer this question. Flocculent spirals -- galaxies without well-defined spiral arms -- are a quite common form of galaxy, and NGC 4414 is one of the closest. Stars and gas near the visible edge of spiral galaxies orbit the center so fast that the gravity from a large amount of unseen dark matter must be present to hold them together. Understanding the matter and dark matter distribution of NGC 4414 helps humanity calibrate the rest of the galaxy and, by deduction, flocculent spirals in general. Further, calibrating the distance to NGC 4414 helps humanity calibrate the cosmological distance scale of the entire visible universe.

https://apod.nasa.gov/apod/ap250407.html ( April 07, 2025)

Why are there so many moonquakes? Analyses of seismometers left on the moon during the Apollo moon landings reveal a surprising number of moonquakes occurring within 100 kilometers of the surface. In fact, 62 moonquakes were detected in data recorded between 1972 and 1977. Many of these moonquakes are not only strong enough to move furniture in a lunar apartment, but the stiff rock of the moon continues to vibrate for many minutes, significantly longer than the softer rock earthquakes on Earth. The cause of the moonquakes remains unknown, but a leading hypothesis include tidal gravity from -- and relative heating by -- our Earth. Regardless of the source, future moon dwellings need to be built to withstand the frequent shakings. Pictured here, Apollo 11 astronaut Buzz Aldrin stands beside a recently deployed lunar seismometer, looking back toward the lunar landing module.

https://apod.nasa.gov/apod/ap250406.html ( April 06, 2025)

A Gargoyles Eclipse

In dramatic silhouette against a cloudy daytime sky over Paris, France, gargoyles cast their monstrous gaze outward from the west facade of Notre Dame Cathedral. Taken on March 29, this telephoto snapshot also captures the dramatic silhouette of a New Moon against the bright solar disk in a partial solar eclipse. Happening high in Parisian skies, the partial eclipse was close to its maximum phase of about 23 percent. Occurring near the end of the first eclipse season of 2025, this partial solar eclipse followed the total eclipse of the Full Moon on March 13/14. The upcoming second eclipse season of 2025 will see a total lunar eclipse on September 7/8 and partial solar eclipse on September 21. The partial solar eclipse will be seen only from locations in planet Earth's southern hemisphere.

https://apod.nasa.gov/apod/ap250405.html ( April 05, 2025)

Hickson 44 in Leo

Scanning the skies for galaxies, Canadian astronomer Paul Hickson and colleagues identified some 100 compact groups of galaxies, now appropriately called Hickson Compact Groups. The four prominent galaxies seen in this intriguing telescopic skyscape are one such group, Hickson 44. The galaxy group is about 100 million light-years distant, far beyond the spiky foreground Milky Way stars, toward the constellation Leo. The two spiral galaxies in the center of the image are edge-on NGC 3190 with its distinctive, warped dust lanes, and S-shaped NGC 3187. Along with the bright elliptical, NGC 3193 (above and left) they are also known as Arp 316. The spiral toward the lower right corner is NGC 3185, the 4th member of the Hickson group. Like other galaxies in Hickson groups, these show signs of distortion and enhanced star formation, evidence of a gravitational tug of war that will eventually result in galaxy mergers on a cosmic timescale. The merger process is now understood to be a normal part of the evolution of galaxies, including our own Milky Way. For scale, NGC 3190 is about 75,000 light-years across at the estimated distance of Hickson 44.

https://apod.nasa.gov/apod/ap250404.html ( April 04, 2025)

The Da Vinci Glow

A 26 hour old Moon poses behind the craggy outline of the Italian Dolomites in this twilight mountain and skyscape. The one second long exposure was captured near moonset on March 30. And while only a a sliver of its sunlit surface is visible, most of the Moon's disk can be seen by earthshine as light reflected from a bright planet Earth illuminates the lunar nearside. Also known as the Moon's ashen glow, a description of earthshine in terms of sunlight reflected by Earth's oceans illuminating the Moon's dark surface was written over 500 years ago by Leonardo da Vinci. Of course earthshine is just the most familiar example of planetshine, the faint illumination of the dark portion of a moon by light reflected from its planet.

https://apod.nasa.gov/apod/ap250403.html ( April 03, 2025)

Why does Jupiter have rings? Jupiter's main ring was discovered in 1979 by NASA's passing Voyager 1 spacecraft, but its origin was then a mystery. Data from NASA's Galileo spacecraft that orbited Jupiter from 1995 to 2003, however, confirmed the hypothesis that this ring was created by meteoroid impacts on small nearby moons. As a small meteoroid strikes tiny Metis, for example, it will bore into the moon, vaporize, and explode dirt and dust off into a Jovian orbit. The featured image of Jupiter in infrared light by the James Webb Space Telescope shows not only Jupiter and its clouds, but this ring as well. Jupiter's Great Red Spot (GRS) -- in comparatively light color on the right, Jupiter's large moon Europa -- in the center of diffraction spikes on the left, and Europa's shadow -- next to the GRS -- are also visible. Several features in the image are not yet well understood, including the seemingly separated cloud layer on Jupiter's right limb.

https://apod.nasa.gov/apod/ap250402.html ( April 02, 2025)

Can the Sun appear to rise twice at the same time? This was just the case a few days ago from Les Escoumins, Quebec, Canada as our Solar System's bright central orb rose just as it was being partially eclipsed by the Moon. The featured video shows this unusual double-sunrise in real time and being reflected by the St. Lawrence River. Soon after the initial two spots of light appear over distant clouds, what appears to be bright horns become visible -- which are really just parts of the Sun not being eclipsed. Soon, the entire eclipsed Sun is visible above the horizon. In all, this broken sunrise took less than two minutes during a partial eclipse that lasted many times longer. Although the Moon circles the Earth once a month (moon-th), it does not always eclipse the Sun because its tilted orbit usually takes it above or below.

https://apod.nasa.gov/apod/ap250401.html ( April 01, 2025)

If you watch long enough, a comet will appear. Before then, you will see our Solar System from inside the orbit of Mercury as recorded by NASA's Parker Solar Probe looping around the Sun. The video captures coronal streamers into the solar wind, a small Coronal Mass Ejection, and planets including, in order of appearance, Mercury, Venus, Saturn, Earth, Mars, and Jupiter. Between the emergence of Earth and Mars, Comet Tempel 1 appears with a distinctive tail. The continuous fleeting streaks are high energy particles from the Sun impacting Parker's sideways looking camera. The featured time-lapse video was taken last year during Encounter 21, Parker's 21st close approach to the Sun. Studying data and images from Parker are delivering a better understanding of the dynamic Sun's effects on Earth's space weather as well as humanity's power grids, spacecraft, and space-faring astronauts.

https://apod.nasa.gov/apod/ap250331.html ( March 31, 2025)

What if the Sun and Moon rose together? That happened yesterday over some northern parts of planet Earth as a partial solar eclipse occurred shortly after sunrise. Regions that experienced the Moon blocking part of the Sun included northeastern parts of North America and northwestern parts of Europe, Asia, and Africa. The featured image was captured yesterday over the Grábrók volcanic crater in Iceland where much of the Sun became momentarily hidden behind the Moon. The image was taken through a cloudy sky but so well planned that the photographer's friend appeared to be pulling the Sun out from behind the Moon. No part of the Earth experienced a total solar eclipse this time. In the distant past, some of humanity was so surprised when an eclipse occurred that ongoing battles suddenly stopped. Today, eclipses are not a surprise and are predicted with an accuracy of seconds.

https://apod.nasa.gov/apod/ap250330.html ( March 30, 2025)

Stereo Helene

Get out your red/blue glasses and float next to Helene, small, icy moon of Saturn. Appropriately named, Helene is a Trojan moon, so called because it orbits at a Lagrange point. A Lagrange point is a gravitationally stable position near two massive bodies, in this case Saturn and larger moon Dione. In fact, irregularly shaped ( about 36 by 32 by 30 kilometers) Helene orbits at Dione's leading Lagrange point while brotherly ice moon Polydeuces follows at Dione's trailing Lagrange point. The sharp stereo anaglyph was constructed from two Cassini images captured during a close flyby in 2011. It shows part of the Saturn-facing hemisphere of Helene mottled with craters and gully-like features.

https://apod.nasa.gov/apod/ap250329.html ( March 29, 2025)

Lunar Dust and Duct Tape

Why is the Moon so dusty? On Earth, rocks are weathered by wind and water, creating soil and sand. On the Moon, eons of constant micrometeorite bombardment have blasted away at the rocky surface creating a layer of powdery lunar soil or regolith. For the Apollo astronauts and their equipment, the pervasive, fine, gritty dust was definitely a problem. On the lunar surface in December 1972, Apollo 17 astronauts Harrison Schmitt and Eugene Cernan needed to repair one of their rover's fenders in an effort to keep the rooster tails of dust away from themselves and their gear. This picture reveals the wheel and fender of their dust covered rover along with the ingenious application of spare maps, clamps, and a grey strip of "duct tape".

https://apod.nasa.gov/apod/ap250328.html ( March 28, 2025)

Messier 81

One of the brightest galaxies in planet Earth's sky is similar in size to our Milky Way Galaxy: big, beautiful Messier 81. Also known as NGC 3031 or Bode's galaxy for its 18th century discoverer, this grand spiral can be found toward the northern constellation of Ursa Major, the Great Bear. The sharp, detailed telescopic view reveals M81's bright yellow nucleus, blue spiral arms, pinkish starforming regions, and sweeping cosmic dust lanes. But some dust lanes actually run through the galactic disk (left of center), contrary to other prominent spiral features. The errant dust lanes may be the lingering result of a close encounter between M81 and the nearby galaxy M82 lurking outside of this frame. Scrutiny of variable stars in M81 has yielded a well-determined distance for an external galaxy -- 11.8 million light-years.

https://apod.nasa.gov/apod/ap250327.html ( March 27, 2025)

You'd think the Pacman Nebula would be eating stars, but actually it is forming them. Within the nebula, a cluster's young, massive stars are powering the pervasive nebular glow. The eye-catching shapes looming in the featured portrait of NGC 281 are sculpted dusty columns and dense Bok globules seen in silhouette, eroded by intense, energetic winds and radiation from the hot cluster stars. If they survive long enough, the dusty structures could also be sites of future star formation. Playfully called the Pacman Nebula because of its overall shape, NGC 281 is about 10,000 light-years away in the constellation Cassiopeia. This sharp composite image was made through narrow-band filters in Spain in mid 2024. It combines emissions from the nebula's hydrogen and oxygen atoms to synthesize red, green, and blue colors. The scene spans well over 80 light-years at the estimated distance of NGC 281.

https://apod.nasa.gov/apod/ap250326.html ( March 26, 2025)

What causes a blue band to cross the Moon during a lunar eclipse? The blue band is real but usually quite hard to see. The featured HDR image of last week's lunar eclipse, however -- taken from Norman, Oklahoma (USA) -- has been digitally processed to exaggerate the colors. The gray color on the upper right of the top lunar image is the Moon's natural color, directly illuminated by sunlight. The lower parts of the Moon on all three images are not directly lit by the Sun since it is being eclipsed -- it is in the Earth's shadow. It is faintly lit, though, by sunlight that has passed deep through Earth's atmosphere. This part of the Moon is red -- and called a blood Moon -- for the same reason that Earth's sunsets are red: because air scatters away more blue light than red. The unusual purple-blue band visible on the upper right of the top and middle images is different -- its color is augmented by sunlight that has passed high through Earth's atmosphere, where red light is better absorbed by ozone than blue.

https://apod.nasa.gov/apod/ap250325.html ( March 25, 2025)

This was once a beach -- on ancient Mars. The featured 360-degree panorama, horizontally compressed, was taken in 2017 by the robotic Curiosity rover that explored the red planet. Named Ogunquit Beach after its terrestrial counterpart, evidence shows that at times long ago the area was underwater, while at other times it was at the edge of an ancient lake. The light peak in the central background is the top of Mount Sharp, the central feature in Gale Crater where Curiosity explored. Portions of the dark sands in the foreground were scooped up for analysis. The light colored bedrock is composed of sediment that likely settled at the bottom of the now-dried lakebed. The featured panorama (interactive version here) was created from over 100 images and seemingly signed by the rover on the lower left.

https://apod.nasa.gov/apod/ap250323.html ( March 23, 2025)

SuperCam Target on Maaz

What's the sound of one laser zapping? There's no need to consult a Zen master to find out, just listen to the first acoustic recording of laser shots on Mars. On Mars Rover Perseverance mission sol 12 (March 2, 2021) the SuperCam instrument atop the rover's mast zapped a rock dubbed Ma'az 30 times from a range of about 3.1 meters. Its microphone recorded the soft staccato popping sounds of the rapid series of SuperCam laser zaps. Shockwaves created in the thin Martian atmosphere as bits of rock are vaporized by the laser shots make the popping sounds, sounds that offer clues to the physical structure of the target. This SuperCam close-up of the Ma'az target region is 6 centimeters (2.3 inches) across. Ma'az means Mars in the Navajo language.

https://apod.nasa.gov/apod/ap250322.html ( March 22, 2025)

The Leo Trio

This popular group leaps into the early evening sky around the March equinox and the northern hemisphere spring. Famous as the Leo Triplet, the three magnificent galaxies found in the prominent constellation Leo gather here in one astronomical field of view. Crowd pleasers when imaged with even modest telescopes, they can be introduced individually as NGC 3628 (bottom left), M66 (middle right), and M65 (top center). All three are large spiral galaxies but tend to look dissimilar, because their galactic disks are tilted at different angles to our line of sight. NGC 3628, also known as the Hamburger Galaxy, is temptingly seen edge-on, with obscuring dust lanes cutting across its puffy galactic plane. The disks of M66 and M65 are both inclined enough to show off their spiral structure. Gravitational interactions between galaxies in the group have left telltale signs, including the tidal tails and warped, inflated disk of NGC 3628 and the drawn out spiral arms of M66. This gorgeous view of the region spans over 1 degree (two full moons) on the sky. Captured with a telescope from Sawda Natheel, Qatar, planet Earth, the frame covers over half a million light-years at the Leo Trio's estimated 30 million light-year distance.

https://apod.nasa.gov/apod/ap250321.html ( March 21, 2025)

The Solar Eclipse Analemma Project

Recorded from 2024 March 10, to 2025 March 1, this composited series of images reveals a pattern in the seasonal drift of the Sun's daily motion through planet Earth's sky. Known to some as an analemma, the figure-eight curve was captured in exposures taken on the indicated dates only at 18:38 UTC from the exact same location south of Stephenville, Texas. The Sun's position on the 2024 solstice dates of June 20 and December 21 would be at the top and bottom of the curve and correspond to the astronomical beginning of summer and winter in the north. Points that lie along the curve half-way between the solstices would mark the equinoxes. The 2024 equinox on September 22, and in 2025 the equinox on March 20 (today) are the start of northern fall and spring. And since one of the exposures was made on 2024 April 8 from the Stephenville location at 18:38:40 UTC, this analemma project also reveals the solar corona in planet Earth's sky during a total solar eclipse.

https://apod.nasa.gov/apod/ap250320.html ( March 20, 2025)