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.
ROSAT Explores The X-Ray Sky
Launched in 1990, the orbiting ROSAT observatory explored the Universe by viewing the entire sky in x-rays -- photons with about 1,000 times more energy than visible light. This…
X-Rays From Antennae Galaxies
A bevy of black holes and neutron stars shine as bright, point-like sources against bubbles of million degree gas in this false-color x-ray image from the orbiting Chandra…
Mount Megantic Magnetic Storm
Plasma from the Sun and debris from a comet both collided with planet Earth last Saturday morning triggering magnetic storms and a meteor shower in a dazzling atmospheric…
Unusual Giant Galaxy NGC 1316
Can unusual giant galaxy NGC 1316 help calibrate the universe? Quite possibly -- if it turns out this atypical galaxy is composed of typical stars. NGC 1316, pictured above , is…
The Solar Spectrum
It is still not known why the Sun's light is missing some colors. Shown above are all the visible colors of the Sun , produced by passing the Sun's light through a prism -like…
Kemble's Cascade
A picturesque chain of unrelated stars is visible with strong binoculars towards the constellation of Camelopardalis . Known as Kemble's Cascade , the asterism contains about 20…
Doomed Star Eta Carinae
Eta Carinae may be about to explode. But no one knows when - it may be next year, it may be one million years from now. Eta Carinae 's mass - about 100 times greater than our Sun…
A Perseid Meteor
This weekend, the annual Perseid Meteor Shower reaches its maximum. Grains of cosmic sand and gravel shed from Comet Swift-Tuttle will streak across the sky as they vaporize…
Fragments of Comet LINEAR
What do you call a bunch of comet fragments anyway ... a flock, a covey, a swarm? The question is definitely relevant to comet LINEAR (C/1999 S4 LINEAR) whose nucleus apparently…
Other Worlds and HD 38529
After the latest round of discovery announcements , the list of known worlds of distant suns has grown to 50 . While extrasolar planet discoveries are sure to continue, none - so…
A Solar Filament Lifts Off
Hot gas frequently erupts from the Sun. One such eruption produced the glowing filament pictured above , which was captured on July 19 by the Earth-orbiting TRACE satellite . The…
Comet LINEAR Disperses
What's happened to the nucleus of Comet LINEAR? The brightest comet this year has unexpectedly broken up into many smaller pieces. The break-up occurred on or about July 25 and…
Nearby Star Episilon Eridani Has a Planet
A planet has been found orbiting a Sun-like star only 10 light-years away. No direct picture of the planet was taken - the planet was discovered by the gravitational wobble it…
The Coma Cluster of Galaxies
Almost every object in the above photograph is a galaxy. The Coma Cluster of Galaxies pictured above is one of the densest clusters known - it contains thousands of galaxies .…
Halley's Nucleus: An Orbiting Iceberg
What does a comet nucleus look like? Formed from the primordial stuff of the solar system, it is thought to resemble a very dirty iceberg. But for active comets, telescopic images…
M15: Dense Globular Star Cluster
Life might get dull at the core of M15 but the sky would always be bright with stars! In fact, only 40,000 light-years away in the constellation Pegasus, M15 is one of the most…
22 Miles From Eros
Last month the NEAR Shoemaker spacecraft swooped closer to Eros, orbiting only 22 miles (36 kilometers) from the center of the asteroid. These two images taken on July 19 (left)…
At the Edge of the Crescent Nebula
The Crescent Nebula is a rapidly expanding shell of gas surrounding a dying star. In this recently released image by the Hubble Space Telescope , a bright dynamic part of the…
X-Rays from Comet LINEAR
Why do comets emit X-rays? First discovered during the passing of Comet Hyakutake in 1996, the reason a cold comet would produce hot X-rays has since remained a mystery. On July…
Comet LINEAR Breaks Up
Unexpectedly, Comet LINEAR is breaking up . In retrospect, clues of its demise have been surfacing all month as the new comet has been approaching the Sun and brightening with…
NGC 2440: Cocoon of a New White Dwarf
Like a butterfly , a white dwarf star begins its life by casting off a cocoon that enclosed its former self. In this analogy, however, the Sun would be a caterpillar and the…
NGC1850: Star Cluster in the LMC
NGC1850 is a large cluster of stars located a mere 166,000 light-years from Earth in our neighboring galaxy the Large Magellanic Cloud (LMC). The colors in this beautiful Hubble…
Moon And Venus Share The Sky
July is drawing to a close and in the past few days, some early morning risers could have looked east and seen a crescent Moon sharing the pre-dawn skies with planets Jupiter and…
Tails Of Comet LINEAR
Comet C/1999 S4 LINEAR is only one of many comets discovered with the Lincoln Near Earth Asteroid Research (LINEAR) telescope operating near Soccoro, New Mexico, USA. Traveling…
Viewing discoveries from 19 August 2000 through 27 July 2000.