Astronomy Picture of the Day

© David Cruz

🌌Mu Cephei Mu Cephei is a very large star. An M-class supergiant some 1500 times the size of the Sun, it is one of the largest stars visible to the unaided eye, and even one of the largest in the entire Galaxy. If it replaced the Sun in our fair Solar System, Mu Cephei would easily engulf Mars and Jupiter. Historically known as Herschel's Garnet Star, Mu Cephei is extremely red. Approximately 28 ...

🌌NGC 1097: Spiral Galaxy with Supernova What's happening in the lower arm of this spiral galaxy? A supernova. Last month, supernova SN 2023rve was discovered with UAE's Al-Khatim Observatory and later found to be consistent with the death explosion of a massive star, possibly leaving behind a black hole. Spiral galaxy NGC 1097 is a relatively close 45 million light years away and visible with a ...

🌌Hidden Orion from Webb The Great Nebula in Orion has hidden stars. 🔗 https://apod.nasa.gov/apod/ap231010.html

© 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 a partial eclipse in 2019, 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 be ...

© Doyle and Shannon Slifer

🌌Plane, Clouds, Moon, Spots, Sun What's that in front of the Sun? The closest object is an airplane, visible just below the Sun's center and caught purely by chance. Next out are numerous clouds in Earth's atmosphere, creating a series of darkened horizontal streaks. Farther out is Earth's Moon, seen as the large dark circular bite on the upper right. Just above the airplane and just below the S ...

🌌The Once and Future Stars of Andromeda This picture of Andromeda shows not only where stars are now, but where stars will be. The big, beautiful Andromeda Galaxy, M31, is a spiral galaxy a mere 2.5 million light-years away. Image data from space-based and ground-based observatories have been combined here to produce this intriguing composite view of Andromeda at wavelengths both inside and outs ...

© Carnegie Institution for Science

🌌Edwin Hubble Discovers the Universe How big is our universe? This question, among others, was debated by two leading astronomers in 1920 in what has since become known as astronomy's Great Debate. Many astronomers then believed that our Milky Way Galaxy was the entire universe. Many others, though, believed that our galaxy was just one of many. In the Great Debate, each argument was detailed, b ...

© Tunc Tezel

🌌Ring of Fire over Monument Valley Tracking along a narrow path, the shadow of a new moon will race across North, Central, and South America, on October 14. When viewed from the shadow path the apparent size of the lunar disk will not quite completely cover the Sun though. Instead, the moon in silhouette will appear during the minutes of totality surrounded by a fiery ring, an annular solar ecli ...

© Abdullah Alharbi

🌌IC 2118: The Witch Head Nebula Does this nebula look like the head of a witch? The nebula is known popularly as the Witch Head Nebula because, it is said, the nebula's shape resembles a Halloween-style caricature of a witch's head. Exactly how, though, can be a topic of imaginative speculation. What is clear is that IC 2118 is about 50 light-years across and made of gas and dust that points to ...

© NASA, ESA, Hubble, HLA; Processing & Copyright: Harshwardhan Pathak

🌌MyCn 18: The Engraved Hourglass Planetary Nebula Do you see the hourglass shape -- or does it see you? If you can picture it, the rings of MyCn 18 trace the outline of an hourglass -- although one with an unusual eye in its center. Either way, the sands of time are running out for the central star of this hourglass-shaped planetary nebula. With its nuclear fuel exhausted, this brief, spectacula ...

© Nicolas Escurat

🌌Sprite Lightning in High Definition Sometimes lightning occurs out near space. One such lightning type is red sprite lightning, which has only been photographed and studied on Earth over the past 25 years. The origins of all types of lightning remain topics for research, and scientists are still trying to figure out why red sprite lightning occurs at all. Research has shown that following a pow ...

© Maxime Daviron

🌌A Desert Eclipse A good place to see a ring-of-fire eclipse, it seemed, would be from a desert. In a desert, there should be relatively few obscuring clouds and trees. Therefore late December of 2019, a group of photographers traveled to the United Arab Emirates and Rub al-Khali, the largest continuous sand desert in world, to capture clear images of an unusual eclipse that would be passing ove ...

© Antonio Tartarini

🌌A Harvest Moon over Tuscany For northern hemisphere dwellers, September's Full Moon was the Harvest Moon. Reflecting warm hues at sunset, it rises behind cypress trees huddled on a hill top in Tuscany, Italy in this telephoto view from September 28. Famed in festival, story, and song, Harvest Moon is just the traditional name of the full moon nearest the autumnal equinox. According to lore the ...

🌌Back from Bennu Back from asteroid 101955 Bennu, a 110-pound, 31-inch wide sample return capsule rests in a desert on planet Earth in this photo, taken at the Department of Defense Utah Test and Training Range near Salt Lake City last Sunday, September 24. Dropped off by the OSIRIS-Rex spacecraft, the capsule looks charred from the extreme temperatures experienced during its blistering descent ...

© Josep Drudis

🌌The Deep Lagoon Ridges of glowing interstellar gas and dark dust clouds inhabit the turbulent, cosmic depths of the Lagoon Nebula. Also known as M8, The bright star forming region is about 5,000 light-years distant. It makes for a popular stop on telescopic tours of the constellation Sagittarius toward the center of our Milky Way Galaxy. Dominated by the telltale red emission of ionized hydroge ...

© Theresa Clarke

🌌STEVE and Milky Way Cross over Rural Road Not every road ends in a STEVE. A week ago, a sky enthusiast's journey began with a goal: to photograph an aurora over Lake Huron. Driving through rural Ontario, Canada, the forecasted sky show started unexpectedly early, causing the photographer to stop before arriving at the scenic Great Lake. Aurora images were taken toward the north -- but over land ...

© Antoine & Dalia Grelin

🌌IC 4592: The Blue Horsehead Reflection Nebula Do you see the horse's head? 🔗 https://apod.nasa.gov/apod/ap230926.html

🌌Arp 142: The Hummingbird Galaxy What's happening to this spiral galaxy? Just a few hundred million years ago, NGC 2936, the upper of the two large galaxies shown at the bottom, was likely a normal spiral galaxy -- spinning, creating stars -- and minding its own business. But then it got too close to the massive elliptical galaxy NGC 2937, just below, and took a turn. Sometimes dubbed the Hummin ...

🌌A Ring of Fire Sunrise Solar Eclipse What's rising above the horizon behind those clouds? It's the Sun. Most sunrises don't look like this, though, because most sunrises don't include the Moon. In the early morning of 2013 May 10, however, from Western Australia, the Moon was between the Earth and the rising Sun. At times, it would be hard for the uninformed to understand what was happening. In ...

© Ian Griffin

🌌Afternoon Analemma An analemma is that figure-8 curve you get when you mark the position of the Sun at the same time each day for one year. To make this one, a 4x5 pinhole camera was set up looking north in southern New Zealand skies. The shutter was briefly opened each clear day in the afternoon at 4pm local time exposing the same photosensitized glass plate for the year spanning September 23, ...

© Jeff Dai

🌌Cosmos in Reflection During the day, over 12,000 large mirrors reflect sunlight at the 100-megawatt, molten-salt, solar thermal power plant at the western edge of the Gobi desert near Dunhuang, Gansu Province, China. Individual mirror panels turn to track the sun like sunflowers. They conspire to act as a single super mirror reflecting the sunlight toward a fixed position, the power station's c ...

🌌Tagging Bennu The OSIRIS-REx spacecraft's arm reached out and touched asteroid 101955 Bennu on October 20, 2020, after a careful approach to the small, near-Earth asteroid's boulder-strewn surface. Dubbed a Touch-And-Go (TAG) sampling event, the 30 centimeter wide sampling head (TAGSAM) appears to crush some of the rocks in this close-up recorded by the spacecraft's SamCam. The image was snappe ...

🌌Methane Discovered on Distant Exoplanet Where else might life exist? One of humanity's great outstanding questions, locating planets where extrasolar life might survive took a step forward in 2019 with the discovery of a significant amount of water vapor in the atmosphere of distant exoplanet K2-18b. The planet and its parent star, K2-18, lie about 124 light years away toward the constellation ...

🌌HH 211: Jets from a Forming Star Do stars always create jets as they form? No one is sure. As a gas cloud gravitationally contracts, it forms a disk that can spin too fast to continue contracting into a protostar. Theorists hypothesize that this spin can be reduced by expelling jets. This speculation coincides with known Herbig-Haro (HH) objects, young stellar objects seen to emit jets -- somet ...

© Maxime Villaeys

🌌The Red Sprite and the Tree The sprite and tree could hardly be more different. To start, the red sprite is an unusual form of lightning, while the tree is a common plant. The sprite is far away -- high in Earth's atmosphere, while the tree is nearby -- only about a football field away. The sprite is fast -- electrons streaming up and down at near light's speed, while the tree is slow -- wood a ...

© Wang Letian (Eyes at Night)