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.
Saturn's Hyperion: A Moon with Odd Craters
What lies at the bottom of Hyperion 's strange craters? Nobody's sure . To help find out, the robot Cassini spacecraft now orbiting Saturn swooped past the sponge-textured moon in…
Shell Galaxies in Pisces
This colorful cosmic skyscape features a peculiar system of galaxies cataloged as Arp 227 some 100 million light-years distant. Swimming within the boundaries of the constellation…
NGC 4449: Close-up of a Small Galaxy
Grand spiral galaxies often seem to get all the glory. Their young, blue star clusters and pink star forming regions along sweeping spiral arms are guaranteed to attract…
NGC 1999: South of Orion
South of the large star-forming region known as the Orion Nebula, lies bright blue reflection nebula NGC 1999 . Also at the edge of the Orion molecular cloud complex some 1,500…
The Solar System from MESSENGER
If you looked out from the center of the Solar System, what would you see? Nearly such a view was taken recently from the MESSENGER spacecraft currently orbiting the Sun from the…
Star Size Comparisons
How big is our Sun compared to other stars? In a dramatic and popular video featured on YouTube, the relative sizes of planets and stars are shown from smallest to largest. The…
Milky Way Over Switzerland
What's visible in the night sky during this time of year? To help illustrate the answer, a beautiful land, cloud, and skyscape was captured earlier this month over Neuchtel ,…
Mammatus Clouds Over Olympic Valley
What's happened to these clouds? Normal cloud bottoms are flat because moist warm air that rises and cools will condense into water droplets at a very specific temperature, which…
Spiral Galaxy NGC 2841 Close Up
A mere 46 million light-years distant, spiral galaxy NGC 2841 can be found in the northern constellation of Ursa Major . This sharp view of the gorgeous island universe shows off…
Planetary Nebula Project
Cast off by dying sunlike stars, planetary nebulae are a brief but glorious final phase of stellar evolution. The gaseous shrouds are ionized by an extremely hot central source,…
X-Class Flare
On Valentine's Day (ET) the Sun unleashed one of its most powerful explosions, an X-class flare . The blast was the largest so far in the new solar cycle. Erupting from active…
Comet Tempel 1 from Stardust-NeXT Spacecraft
No comet has ever been visited twice before. Therefore, the unprecedented pass of the Stardust-NeXT spacecraft near Comet Tempel 1 earlier this week gave humanity a unique…
The North America Nebula in Infrared
The North America Nebula can do what most North Americans cannot -- form stars. Precisely where in the nebula these stars are forming has been mostly obscured by some of the…
The Rosette Nebula
Would the Rosette Nebula by any other name look as sweet ? The bland New General Catalog designation of NGC 2237 doesn't appear to diminish the appearance of this flowery emission…
Ice Fishing for Cosmic Neutrinos
Scientists are melting holes in the bottom of the world. In fact, almost 100 holes melted near the South Pole are now being used as astronomical observatories. Astronomers with…
Simeis 147: Supernova Remnant
It's easy to get lost following the intricate filaments in this detailed mosaic image of faint supernova remnant Simeis 147. Also cataloged as Sh2-240 and seen towards the…
Star Colors in Orion
What determines a star's color ? Its temperature. Red stars are cool, with surface temperatures of around 3,000 kelvins (K) , while blue stars are hotter and can have temperatures…
Hanny's Voorwerp
Hanny's Voorwerp , Dutch for “Hanny's Object”, is enormous, about the size of our own Milky Way Galaxy. Glowing strongly in the greenish light produced by ionized oxygen atoms,…
NGC 2174: Stars Versus Mountains
It's stars versus gas mountains in NGC 2174 and the stars are winning. More precisely, the energetic light and winds from massive newly formed stars are evaporating and dispersing…
Iridescent Clouds from the Top of the World Highway
Why would a cloud appear to be different colors? A relatively rare phenomenon known as iridescent clouds can show unusual colors vividly or a whole spectrum of colors…
Sun 360: STEREO Captures Views of the Entire Sun
For the first time, the entire Sun is being imaged all at once. This has become possible because the two STEREO satellites orbiting and monitoring the Sun are now on opposite…
An Anomalous SETI Signal
No one knows for sure what caused this signal . There is a slight possibility that it just might originate from an extraterrestrial intelligence . The bright colors on the blue…
Apollo 14: A View from Antares
Forty years ago , while looking out the window of Apollo 14's Lunar Module Antares , astronaut Ed Mitchell snapped a series of photos of the lunar surface, assembled into this…
Zeta Oph: Runaway Star
Like a ship plowing through cosmic seas, runaway star Zeta Ophiuchi produces the arcing interstellar bow wave or bow shock seen in this stunning infrared portrait from the WISE…
Viewing discoveries from 27 February 2011 through 4 February 2011.