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.
Cassini Approaches Saturn
Cassini, a robot spacecraft launched in 1997 by NASA , is close enough now to resolve many rings and moons of its destination planet: Saturn . The spacecraft has closed to about…
The International Space Station Expands Again
The developing International Space Station (ISS) has changed its appearance yet again. Last month the Space Shuttle Atlantis visited the ISS and installed the third of eleven…
NGC 604: Giant Stellar Nursery
Scattered within this cavernous nebula , cataloged as NGC 604 , are over 200 newly formed hot, massive, stars. At 1,500 light-years across, this expansive cloud of interstellar…
Europa's Freckles
Europa , one of Jupiter's large Galilean moons , may well possess an ocean of liquid water hidden beneath its icy surface -- and so holds the tantalizing possibility of life. In…
Aurora in the Night
For much of the month of October, traveling shock waves from the Sun and solar wind gusts have buffeted planet Earth's magnetosphere . As a result, skywatchers at high latitudes…
Leonids Over Uluru
Will this year's Leonid meteor shower be as good as last year 's? No one knows for sure. Possibly, however, in the waning nighttime hours of November 18 and lasting throughout…
A Lunar Rille
What could cause a long indentation on the Moon ? First discovered over 200 years ago with a small telescope, rilles (rhymes with pills) appear all over the Moon . Three types of…
Earth's Richat Structure
What on Earth is that? The Richat Structure in the Sahara Desert of Mauritania is easily visible from space because it is nearly 50 kilometers across. Once thought to be an impact…
Asteroid Gaspra's Best Face
Asteroid 951 Gaspra is a huge rock tumbling in space. Gaspra became one of the best-studied asteroids in 1991 when the spacecraft Galileo flew by. In the above photograph , subtle…
Dark Matter, X-rays, and NGC 720
Elliptical galaxy NGC 720 is enveloped in a cosmic cloud of x-ray emitting gas. Seen in this false color image from the Chandra X-ray Observatory , the extreme temperature of the…
Journey to the Center of the Galaxy
In Jules Verne 's science fiction classic A Journey to the Center of the Earth , Professor Hardwigg and his fellow explorers encounter many strange and exciting wonders. What…
Gullies on Mars
The Gullies of Mars would probably not have been sensational enough for the title of a vintage Edgar Rice Burroughs story about the Red Planet. But it would get the attention of…
Liftoff With the Space Shuttle
What would it look like to see a Space Shuttle liftoff from just above the shuttle? Because the answer has value in assessing spacecraft performance, NASA attached a small…
A Small Double Ozone Hole in 2002
As expected, the ozone hole near Earth's South Pole is back again this year. This time, however, it's smaller than the past two years, and has an unusual double lobe structure.…
M31: The Andromeda Galaxy
Andromeda is the nearest major galaxy to our own Milky Way Galaxy . Our Galaxy is thought to look much like Andromeda . Together these two galaxies dominate the Local Group of…
The Space Shuttle Docked with Mir
Before there was the International Space Station , the reigning orbiting spaceport was Russia's Mir. Pictured above in 1995, the United States Space Shuttle Atlantis docked with…
Io's Surface: Under Construction
Like the downtown area of your favorite city, the roads you drive to work on, and any self-respecting web site ... Io's surface is constantly under construction . This moon of…
At the Center of the Milky Way
At the center of our Milky Way Galaxy lies a black hole with over 2 million times the mass of the Sun. Once a controversial claim, this astounding conclusion is now virtually…
Centaurus A: Young Blue Star Stream
Almost lost in this cosmic jumble of stars, gas and dust is a faint but definite blue arc -- a stream of young stars whose formation was probably triggered as a small dwarf galaxy…
Oklo: Ancient African Nuclear Reactors
The remnants of nuclear reactors nearly two billion years old were found in the 1970s in Africa. These reactors are thought to have occurred naturally. No natural reactors exist…
Aurora's Ring
Gusting solar winds and blasts of charged particles from the Sun made the early days of October rewarding ones for those anticipating auroras . While out enjoying the stormy space…
IC 5146: The Cocoon Nebula
How did this nebula get created? The Cocoon Nebula , cataloged as IC 5146, is a strikingly beautiful nebula located about 4,000 light years away toward the constellation of Cygnus…
CG4: A Ruptured Cometary Globule
The odd looking “creature” to the right of center in the above photo is a gas cloud known as a cometary globule . This globule, however, has ruptured. Cometary globules are…
Chandra Deep Field
Officially the Chandra Deep Field - South , this picture represents the deepest ever x-ray image of the Universe. One million seconds of accumulated exposure time with the…
Viewing discoveries from 4 November 2002 through 12 October 2002.