Astronomy Picture of the Day

🌌Ganymede from Juno What does the largest moon in the Solar System look like? Jupiter's moon Ganymede, larger than even Mercury and Pluto, has an icy surface speckled with bright young craters overlying a mixture of older, darker, more cratered terrain laced with grooves and ridges. The cause of the grooved terrain remains a topic of research, with a leading hypothesis relating it to shifting ic ...

🌌A Supercell Thunderstorm Over Texas Is that a cloud or an alien spaceship? It's an unusual and sometimes dangerous type of thunderstorm cloud called a supercell. Supercells may spawn damaging tornados, hail, downbursts of air, or drenching rain. Or they may just look impressive. A supercell harbors a mesocyclone -- a rising column of air surrounded by drafts of falling air. Supercells could occ ...

© Elliot Severn

🌌Eclipse on the Water clipses tend to come in pairs. Twice a year, during an eclipse season that lasts about 34 days, Sun, Moon, and Earth can nearly align. Then the full and new phases of the Moon separated by just over 14 days create a lunar and a solar eclipse. Often partial eclipses are part of any eclipse season. But sometimes the alignment at both new moon and full moon phases during a sin ...

© Zev Hoover

🌌Eclipse Flyby On June 10 a New Moon passed in front of the Sun. In silhouette only two days after reaching apogee, the most distant point in its elliptical orbit, the Moon's small apparent size helped create an annular solar eclipse. The brief but spectacular annular phase of the eclipse shows a bright solar disk as a ring of fire when viewed along its narrow, northerly shadow track across plan ...

© Vincenzo Mirabella

🌌Circular Sun Halo Want to see a ring around the Sun? It's easy to do in daytime skies around the world. Created by randomly oriented ice crystals in thin high cirrus clouds, circular 22 degree halos are visible much more often than rainbows. This one was captured by smart phone photography on May 29 near Rome, Italy. Carefully blocking the Sun, for example with a finger tip, is usually all that ...

© Helmut Eder

🌌A Total Lunar Eclipse Corona This moon appears multiply strange. This moon was a full moon, specifically called a Flower Moon at this time of the year. But that didn't make it strange -- full moons occur once a month (moon-th). This moon was a supermoon, meaning that it reached its full phase near its closest approach to the Earth in its slightly elliptical orbit. Somewhat strange, a supermoon ...

🌌A Face in the Clouds of Jupiter from Juno What do you see in the clouds of Jupiter? On the largest scale, circling the planet, Jupiter has alternating light zones and reddish-brown belts. Rising zone gas, mostly hydrogen and helium, usually swirls around regions of high pressure. Conversely, falling belt gas usually whirls around regions of low pressure, like cyclones and hurricanes on Earth. B ...

© Chuck Ayoub

🌌A Bright Nova in Cassiopeia What’s that new spot of light in Cassiopeia? A nova. Although novas occur frequently throughout the universe, this nova, known as Nova Cas 2021 or V1405 Cas, became so unusually bright in the skies of Earth last month that it was visible to the unaided eye. Nova Cas 2021 first brightened in mid-March but then, unexpectedly, became even brighter in mid-May and remaine ...

© Elias Chasiotis

🌌A Distorted Sunrise Eclipse Yes, but have you ever seen a sunrise like this? Here, after initial cloudiness, the Sun appeared to rise in two pieces and during partial eclipse, causing the photographer to describe it as the most stunning sunrise of his life. The dark circle near the top of the atmospherically-reddened Sun is the Moon -- but so is the dark peak just below it. This is because alon ...

🌌The Shining Clouds of Mars The weathered and layered face of Mount Mercou looms in the foreground of this mosaic from the Curiosity Mars rover's Mast Camera. Made up of 21 individual images the scene was recorded just after sunset on March 19, the 3,063rd martian day of Curiosity's on going exploration of the Red Planet. In the martian twilight high altitude clouds still shine above, reflecting ...

© Chirag Upreti

🌌Blood Monster Moon On May 26, the Full Flower Moon was caught in this single exposure as it emerged from Earth's shadow and morning twilight began to wash over the western sky. Posing close to the horizon near the end of totality, an eclipsed lunar disk is framed against bare oak trees at Pinnacles National Park in central California. The Earth's shadow isn't completely dark though. Faintly suf ...

© Ignacio Diaz Bobillo

🌌Millions of Stars in Omega Centauri Globular star cluster Omega Centauri, also known as NGC 5139, is some 15,000 light-years away. The cluster is packed with about 10 million stars much older than the Sun within a volume about 150 light-years in diameter. It's the largest and brightest of 200 or so known globular clusters that roam the halo of our Milky Way galaxy. Though most star clusters con ...

🌌The Galactic Center in Stars, Gas, and Magnetism What's going on near the center of our galaxy? To help find out, a newly detailed panorama has been composed that explores regions just above and below the galactic plane in radio and X-ray light. X-ray light taken by the orbiting Chandra Observatory is shown in orange (hot), green (hotter), and purple (hottest) and superposed with a highly detai ...

🌌Starlink over Orion What are those streaks across Orion? Most are reflections of sunlight from numerous Earth-orbiting Starlink satellites. Appearing by eye as a series of successive points floating across a twilight sky, the increasing number of SpaceX Starlink communication satellites are causing concern among many astronomers. On the positive side, Starlink and similar constellations make th ...

© NASAJPL-CaltechSpace Science InstituteCassini

🌌Mimas: Small Moon with a Big Crater Whatever hit Mimas nearly destroyed it. What remains is one of the largest impact craters on one of Saturn's smallest round moons. Analysis indicates that a slightly larger impact would have destroyed Mimas entirely. The huge crater, named Herschel after the 1789 discoverer of Mimas, Sir William Herschel, spans about 130 kilometers and is featured here. Mimas ...

© Daniele Boffelli

🌌Aurora over Clouds Auroras usually occur high above the clouds. The auroral glow is created when fast-moving particles ejected from the Sun impact the Earth's magnetosphere, from which charged particles spiral along the Earth's magnetic field to strike atoms and molecules high in the Earth's atmosphere. An oxygen atom, for example, will glow in the green light commonly emitted by an aurora afte ...

🌌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, the history of constant micrometeorite bombardment has 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 ...

© Barden Ridge Observatory

🌌Total Lunar Eclipse from Sydney The reddened shadow of planet Earth plays across the lunar disk in this telescopic image taken on May 26 near Sydney, New South Wales, Australia. On that crisp, clear autumn night a Perigee Full Moon slid through the northern edge of the shadow's dark central umbra. Short for a lunar eclipse, its total phase lasted only about 14 minutes. The Earth's shadow was no ...

© John Kraus

🌌Mid-Eclipse and Milky Way May's perigee Full Moon slid through Earth's shadow yesterday entertaining night skygazers in regions around the Pacific. Seen from western North America, it sinks toward the rugged Sierra Nevada mountain range in this time-lapse series of the total lunar eclipse. Low on the western horizon the Moon was captured at mid-eclipse with two separate exposures. Combined they ...

🌌The Outburst Clouds of Star AG Car What created these unusual clouds? At the center of this 2021 Hubble image sits AG Carinae, a supergiant star located about 20,000 light-years away in the southern constellation Carina. The star's emitted power is over a million times that of the Sun, making AG Carinae one of the most luminous stars in our Milky Way galaxy. AG Carinae and its neighbor Eta Cari ...

🌌The Moon During a Total Lunar Eclipse How does the Moon's appearance change during a total lunar eclipse? The featured time-lapse video was digitally processed to keep the Moon bright and centered during the 5-hour eclipse of 2018 January 31. At first the full moon is visible because only a full moon can undergo a lunar eclipse. Stars move by in the background because the Moon orbits the Earth ...

© Chris KotsiopoulosGreekSky

🌌Lightning Eclipse from the Planet of the Goats Thunderstorms almost spoiled this view of the spectacular 2011 June 15 total lunar eclipse. Instead, storm clouds parted for 10 minutes during the total eclipse phase and lightning bolts contributed to the dramatic sky. Captured with a 30-second exposure the scene also inspired one of the more memorable titles (thanks to the astrophotographer) in A ...

© César Vega Toledano Rollover Annotation: Judy Schmidt

🌌The Galaxy Tree First came the trees. In the town of Salamanca, Spain, the photographer noticed how distinctive a grove of oak trees looked after being pruned. Next came the galaxy. The photographer stayed up until 2 am, waiting until the Milky Way Galaxy rose above the level of a majestic looking oak. From this carefully chosen perspective, dust lanes in the galaxy appear to be natural continu ...

© Ginge Anvik

🌌Markarian's Chain Near the heart of the Virgo Galaxy Cluster the string of galaxies known as Markarian's Chain stretches across this deep telescopic field of view. Anchored in the frame at bottom center by prominent lenticular galaxies, M84 (bottom) and M86, you can follow the chain up and to the right. Near center you'll spot the pair of interacting galaxies NGC 4438 and NGC 4435, known to som ...

🌌Utopia on Mars sive Utopia Planitia on Mars is strewn with rocks and boulders in this 1976 image. Constructed from the Viking 2 lander's color and black and white image data, the scene approximates the appearance of the high northern martian plain to the human eye. For scale, the prominent rounded rock near center is about 20 centimeters (just under 8 inches) across. Farther back on the right s ...

© Martin Dufour

🌌M13: The Great Globular Cluster in Hercules In 1716, English astronomer Edmond Halley noted, "This is but a little Patch, but it shews itself to the naked Eye, when the Sky is serene and the Moon absent." Of course, M13 is now less modestly recognized as the Great Globular Cluster in Hercules, one of the brightest globular star clusters in the northern sky. Sharp telescopic views like this one ...