Browse NASA Astronomy Picture of the Day archive by date and media: Archive Discoveries
Browse the NASA APOD archive without needing the exact date first. Filter by media type and keep moving deeper into older images and videos.
Io's Sodium Cloud
Explanation : Io has its own cloud. Jupiter 's most active moon is visible on the left of the above false-color photograph , with its left side illuminated by sunlight. But what…
Sputnik: Traveling Companion Courtesy:
Explanation : Sputnik means “traveling companion”. Despite the innocuous sounding name, the launch of the Earth's first “artificial moon”, Sputnik 1 , by the Soviets on October 4,…
The Perseus Cluster of Galaxies
Explanation : Here is one of the largest objects that anyone will ever see on the sky. Each of the fuzzy blobs in the above picture is a galaxy , together making up the Perseus…
Hale-Bopp Polarized
Explanation : Light polarization is familiar to many outdoor enthusiasts who use polarizing sunglasses to cut the glare of reflected light. These two views of comet Hale-Bopp also…
The Frothy Milky Way
Explanation : Astronomers have recently discovered that looking at dust along the plane of our Milky Way Galaxy is a bit like looking into a frothy glass of beer. The dust between…
Antlia: A New Galactic Neighbor
Explanation : Meet Antlia, a newly discovered neighbor of our Milky Way Galaxy. Announced just last week, this faint member of our Local Group of Galaxies has only about one…
Historic Optical Flash Fades
Explanation : The largest telescopes in the world have scrambled to point toward this faint, fading object. Why? Because it may well be the first active optical counterpart ever…
Big Sky Comet
Explanation : On April 17 th , “Big Sky” country sure lived up to its name. The dark skies over the US states of Wyoming, Montana and the Dakotas were quite busy, as shown by this…
Moon Robot: Lunokhod 1
Explanation : On November 17, 1970 the Soviet Luna 17 spacecraft landed the first roving remote-controlled robot on the Moon . Known as Lunokhod 1, it weighed just under 2,000…
Spiral Galaxy M83
Explanation : The long winding arms of this nearby spiral galaxy define it as the “Southern Pinwheel.” But M83 is quite a typical spiral - much like our own Milky Way Galaxy.…
Solar Storm Causes X-Ray Aurora
Explanation : On April 7 , the SOHO spacecraft spotted a Solar Storm ejecting a cloud of energetic particles toward planet Earth. The plasma cloud's center missed Earth, but high…
Pwyll: Icy Crater of Europa
Explanation : The impact crater Pwyll ( a name from Celtic Mythology ) is thought to represent one of the youngest features on the surface of Jupiter's moon Europa . A combination…
A Star Cluster Through Hale-Bopp's Tail
Explanation : Comet Hale-Bopp continues to look impressive. The photograph above captured the comet on April 7 th passing nearly in front of M34 , a star cluster in the…
Hale-Bopp and the Plateau de Bure Interferometer
Explanation : Comet Hale-Bopp is being observed by many different telescopes. Here the comet is pictured behind the array of radio telescopes which compose the Plateau de Bure…
Hale-Bopp's Hoods
Explanation : Comet Hale-Bopp is spinning. The nucleus of the comet is a dirty snowball about 25 miles in diameter that spins about once every 12 hours . As Comet Hale-Bopp spins,…
Jets from SS433
Explanation : SS433 is one of the most exotic star systems known. Its unremarkable name stems from its inclusion in a catalog of stars which emit radiation characteristic of…
Arecibo: The Largest Telescope
Explanation : The Arecibo radio telescope is currently the largest single-dish telescope in the world. First opening in 1963, this 305 meter (1000 foot) radio telescope resides in…
The Sun Puffs
Explanation : The Earth has once again endured a burst of particles from the Sun. The latest storm , which began Monday, was one of the best documented solar storms to date. At 10…
Europa's Ice Rafts
Explanation : The surface of Jupiter 's moon Europa has shifted. Photographs released yesterday of Europa's surface taken by the spacecraft Galileo show that the smooth moon's icy…
Oceans Under Jupiter's Europa?
Explanation : Is there life beneath Europa? Today, new results are being announced (at about 2 pm EST) about the possibility of oceans under Jupiter 's moon Europa . The existence…
Comet Hale-Bopp Over New York City
Explanation : What's that point of light above the World Trade Center ? It's Comet Hale-Bopp ! Both faster than a speeding bullet and able to “leap” tall buildings in its single…
GRB970228: What's There?
Explanation : Could this fuzzy blob be the key to the whole gamma-ray burst (GRB) mystery ? Astronomers the world over are now scrambling to determine the true nature of the…
Mercury Astronauts and a Redstone
Explanation : Space suited project Mercury astronauts John H. Glenn , Virgil I. Grissom , and Alan B. Shepard Jr. (left to right) are pictured here posing in front of a Redstone…
A Black Hole in M87?
Explanation : The center of nearby giant galaxy M87 is a dense and violent place. In this 1994 photograph by the Hubble Space Telescope , a disk of hot gas was found to be…
Viewing discoveries from 28 April 1997 through 5 April 1997.