Astronomy Picture of the Day

🌌Orbits of Potentially Hazardous Asteroids 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 t ...

🌌Mars Rock Rochette Taken on mission sol 180 (August 22) this sharp image from a Hazard Camera on the Perseverance rover looks out across a rock strewn floor of Jezero crater on Mars. At 52.5 centimeters (21 inches) in diameter, one of the rover's steerable front wheels is at lower left in the frame. Near center is a large rock nicknamed Rochette. Mission planners don't want to avoid Rochette th ...

© Robert Eder

🌌Elephant's Trunk and Caravan Like an illustration in a galactic Just So Story, the Elephant's Trunk Nebula winds through the emission nebula and young star cluster complex IC 1396, in the high and far off constellation of Cepheus. Also known as vdB 142, seen on the left the cosmic elephant's trunk is over 20 light-years long. Removed by digital processing, no visible stars are in this detailed ...

© Giorgia Hofer

🌌A Blue Hour Full Moon Nature photographers and other fans of planet Earth always look forward to the blue hour. That's the transition in twilight, just before sunrise or after sunset, when the Sun is below the horizon but land and sky are still suffused with a beautiful blue light. After sunset on August 21, this blue hour snapshot captured the nearly full Moon as it rose opposite the Sun, abov ...

🌌Solar System Ball Drop Does a ball drop faster on Earth, Jupiter, or Uranus? The featured animation shows a ball dropping from one kilometer high toward the surfaces of famous solar system bodies, assuming no air resistance. The force of gravity depends on the mass of the attracting object, with higher masses pulling down with greater forces. But gravitational force also depends on distance fro ...

🌌PDS 70: Disk, Planets, and Moons It's not the big disk that's attracting the most attention. Although the big planet-forming disk around the star PDS 70 is clearly imaged and itself quite interesting. It's also not the planet on the right, just inside the big disk, that’s being talked about the most. Although the planet PDS 70c is a newly formed and, interestingly, similar in size and mass to J ...

🌌Abell 3827: Cannibal Cluster Gravitational Lens Is that one galaxy or three? Toward the right of the featured Hubble image of the massive galaxy cluster Abell 3827 is what appears to be a most unusual galaxy -- curved and with three centers. A detailed analysis, however, finds that these are three images of the same background galaxy -- and that there are at least four more images. Light we see ...

© David A. HardyPPARC

🌌Explosions from White Dwarf Star RS Oph Spectacular explosions keep occurring in the binary star system named RS Ophiuchi. Every 20 years or so, the red giant star dumps enough hydrogen gas onto its companion white dwarf star to set off a brilliant thermonuclear explosion on the white dwarf's surface. At about 5,000 light years distant, the resulting nova explosions cause the RS Oph system to b ...

© Christopher Go

🌌Triple Transit and Mutual Events These three panels feature the Solar System's ruling gas giant Jupiter on August 15 as seen from Cebu City, Phillipines, planet Earth. On that date the well-timed telescopic views detail some remarkable performances, transits and mutual events, by Jupiter's Galilean moons. In the top panel, Io is just disappearing into Jupiter's shadow at the far right, but the ...

© Balint Lengyel

🌌Three Perseid Nights Frames from a camera that spent three moonless nights under the stars create this composite night skyscape. They were recorded during August 11-13 while planet Earth was sweeping through the dusty trail of comet Swift-Tuttle. One long exposure, untracked for the foreground, and the many star tracking captures of Perseid shower meteors were taken from the village of Magyareg ...

© Miguel Claro

🌌Bright Meteor, Starry Sky Plowing through Earth's atmosphere at 60 kilometers per second, this bright perseid meteor streaks along a starry Milky Way. Captured in dark Portugal skies on August 12, it moves right to left through the frame. Its colorful trail starts near Deneb (alpha Cygni) and ends near Altair (alpha Aquilae), stars of the northern summer triangle. In fact this perseid meteor ve ...

© Robert Gendler

🌌Rings Around the Ring Nebula 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. Thi ...

🌌M57: The Ring Nebula from Hubble cept for the rings of Saturn, the Ring Nebula (M57) is probably the most famous celestial circle. Its classic appearance is understood to be due to our own perspective, though. The recent mapping of the expanding nebula's 3-D structure, based in part on this clear Hubble image,indicates that the nebula is a relatively dense, donut-like ring wrapped around the mi ...

© Daniel Korona

🌌Perseid Meteor, Red Sprites, and Nova RS Ophiuchus This was an unusual sky. It wasn't unusual because of the central band the Milky Way Galaxy, visible along the image left. Most dark skies show part of the Milky Way. It wasn't unusual because of the bright meteor visible on the upper right. Many images taken during last week's Perseid Meteor Shower show meteors, although this Perseid was parti ...

© Luo Hongyang

🌌Perseid Rain Comet dust rained down on planet Earth last week, streaking through dark skies in the annual Perseid meteor shower. The featured picture is a composite of many images taken from the same location over the peak night of the Perseids. The umbrella was not needed as a shield from meteors, since they almost entirely evaporate high in the Earth's atmosphere. Many of the component images ...

© Marzena Rogozinska

🌌Island Universe, Cosmic Sand Stars in our own Milky Way Galaxy are scattered through this eye-catching field of view. From the early hours after midnight on August 13, the 30 second exposure of the night sky over Busko-Zdroj, Poland records the colorful and bright trail of a Perseid meteor. Seen near the peak of the annual Perseid meteor shower it flashes from lower left to upper right. The hur ...

🌌A Perfect Spiral If not perfect then this spiral galaxy is at least one of the most photogenic. An island universe of about 100 billion stars, 32 million light-years away toward the constellation Pisces, M74 presents a gorgeous face-on view. Classified as an Sc galaxy, the grand design of M74's graceful spiral arms are traced by bright blue star clusters and dark cosmic dust lanes. This sharp c ...

© Mike Selby

🌌A Beautiful Trifid The beautiful Trifid Nebula is a cosmic study in contrasts. Also known as M20, it lies about 5,000 light-years away toward the nebula rich constellation Sagittarius. A star forming region in the plane of our galaxy, the Trifid does illustrate three different types of astronomical nebulae; red emission nebulae dominated by light from hydrogen atoms, blue reflection nebulae pro ...

© Michael F Johnston

🌌Mammatus Clouds over Saskatchewan When do cloud bottoms appear like bubbles? Normally, cloud bottoms are flat. This is because moist warm air that rises and cools will condense into water droplets at a specific temperature, which usually corresponds to a very specific height. As water droplets grow, an opaque cloud forms. Under some conditions, however, cloud pockets can develop that contain la ...

🌌Fire in Space What does fire look like in space? In the gravity on Earth, heated air rises and expands, causing flames to be teardrop shaped. In the microgravity of the air-filled International Space Station (ISS), however, flames are spheres. Fire is the rapid acquisition of oxygen, and space flames meet new oxygen molecules when they float by randomly from all directions -- creating the envel ...

© Tomas SlovinskySlovakiaPetr HoralekCzech RepublicInstitute of Physics in Opava

🌌Perseus and the Lost Meteors What's the best way to watch a meteor shower? This question might come up later this week when the annual Perseid Meteor Shower peaks. One thing that is helpful is a dark sky, as demonstrated in the featured composite image of last year's Perseids. Many more faint meteors are visible on the left image, taken through a very dark sky in Slovakia, than on the right ima ...

🌌A Perseid Below rthlings typically watch meteor showers by looking up. But this remarkable view, captured on August 13, 2011 by astronaut Ron Garan, caught a Perseid meteor by looking down. From Garan's perspective onboard the International Space Station orbiting at an altitude of about 380 kilometers, the Perseid meteors streak below, swept up dust left from comet Swift-Tuttle heated to incand ...

🌌Jezero Crater: Raised Ridges in 3D Get out your red-blue glasses and hover over the surface of Mars. Taken on July 24, the 3D color view is from the Mars Ingenuity Helicopter's 10th flight above the Red Planet. Two images from Ingenuity's color camera, both captured at an altitude of 12 meters (40 feet), but a few meters apart to provide a stereo perspective, were used to construct the color an ...

© Vikas Chander

🌌Stars and Dust Across Corona Australis Cosmic dust clouds cross a rich field of stars in this telescopic vista near the northern boundary of Corona Australis, the Southern Crown. Less than 500 light-years away the dust clouds effectively block light from more distant background stars in the Milky Way. Top to bottom the frame spans about 2 degrees or over 15 light-years at the clouds' estimated ...

© Eduardo Schaberger Poupeau

🌌Tycho and Clavius South is up in this detailed telescopic view across the Moon's rugged southern highlands. Captured on July 20, the lunar landscape features the Moon's young and old, the large craters Tycho and Clavius. About 100 million years young, Tycho is the sharp-walled 85 kilometer diameter crater near center, its 2 kilometer tall central peak in bright sunlight and dark shadow. Debris ...

🌌EHT Resolves Central Jet from Black Hole in Cen A How do supermassive black holes create powerful jets? To help find out, the Event Horizon Telescope (EHT) imaged the center of the nearby active galaxy Centaurus A. The cascade of featured inset images shows Cen A from it largest, taking up more sky than many moons, to its now finest, taking up only as much sky as an golf ball on the moon. The n ...