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.
Cas A Supernova Remnant in X-Rays
The complex shell of a star seen to explode 300 years ago is helping astronomers to understand how that star exploded. The above recently released image of supernova remnant…
The Largest Rock Known
There, that faint dot in the center - that's the largest rock known. It is larger than every known asteroid , moon , and comet nucleus . It is larger than any other rocky planet .…
The Millennium that Defines Universe
Welcome to the millennial year at the threshold of millennium three . During millennium two , humanity continually redefined its concept of “Universe”: first as spheres centered…
The Millennium that Defined Earth
When the second millennium began , people generally knew that the Earth was round , but few saw much of it beyond their local village. As the millennium progressed, humans mapped…
The Century that Defined Galaxy
As the twentieth century dawned a debate raged over whether the Milky Way was the entire universe. The 1920s brought observations of spiral-nebulae that housed familiar but faint…
The Decade that Defined Star System
As the 1990s began, the only planetary star system known was our own Solar System . The first extra-solar star system was discovered orbiting a pulsar in 1991. Slight changes in…
A Year Of New Perspectives
Fittingly, 1999 saw a decade of astronomical discoveries to an end with portents of things to come - embodied in new spacecraft, telescopes, and perspectives to explore the…
Solar Moss
Discovered in recent close-up pictures of the Sun from NASA's Transition Region And Coronal Explorer (TRACE) spacecraft, this spongy-looking stuff has a temperature of 2 million…
West Of The Great Red Spot
The turbulent region West of Jupiter's Great Red Spot is highlighted in this picture constructed from data recorded by the Galileo spacecraft . The image is color coded to show…
An Earth Ornament
The Apollo 8 astronauts spent the 1968 Christmas Season orbiting the Moon , returning with striking images of both Moon and Earth from space - pictures which inspired the world.…
Hubble Holiday
How would you like to spend your holiday in low earth orbit? That's what the crew of the space shuttle Discovery is doing as they deliver six new gyros and a faster main computer…
Unusual Aurora During Solar Wind Dropout
On May 10, for some unknown reason, the Solar Wind virtually stopped. Normally our Sun emits a wind of between five and ten energetic particles per cubic centimeter moving outward…
Perigee Moon, Apogee Moon
Tonight, those blessed with clear skies can enjoy a glorious full moon , the last full moon of the “Y1.9K”s. In fact, tonight's moon will be a full-perigee-solstice moon, reaching…
XMM Launched
X-ray astronomy entered a golden age earlier this month with the successful launch of the X-ray Multi-Mirror (XMM) satellite. XMM 's three huge telescope barrels each hold 58…
Lava Fountain on Jupiter's Io
A lava fountain shooting over a kilometer high has been discovered on Jupiter 's moon Io . The robot Galileo spacecraft orbiting Jupiter photographed the volcanic eruption during…
Accretion Disk Binary System
Our Sun is unusual in that it is alone - most stars occur in multiple or binary systems . In a binary system, the higher mass star will evolve faster and will eventually become a…
Irregular Galaxy Sextans A
Grand spiral galaxies often seem to get all the glory. Their newly formed, bright, blue star clusters found along beautiful, symmetric spiral arms are guaranteed to attract…
Hot Gas In Hydra A
The Hydra A galaxy cluster is really big. In fact, such clusters of galaxies are the largest gravitationally bound objects in the Universe. But individual galaxies are too cool to…
Supernova Remnant In M82
This false-color radio wavelength picture of an expanding stellar debris cloud is the product of one of the largest radio astronomy experiments ever. Combining the output of 20…
A Nova In Aquila
On December 1st , experienced observers patroling the night sky with binoculars noticed what seemed to be a new star in the constellation of Aquila (The Eagle) . It wasn't really…
High Velocity Clouds and the Milky Way
Where are these gas clouds going so quickly? High velocity clouds (HVCs) of gas have been seen for decades but their origins and destinations have remained mysterious. Recent…
A Magellanic Starfield
Stars of many types and colors are visible in this Hubble Space Telescope vista of the Large Magellanic Cloud (LMC). Over 10,000 stars are visible -- the brightest of which are…
NGC 4314: A Nuclear Starburst Ring
Is this old galaxy up to new tricks? The barred spiral galaxy NGC 4314 is billions of years old, but its appearance has changed markedly over just the past few millions of years.…
A Close Encounter Of The Stellar Kind
The unassuming star centered in this sky view will one day be our next door stellar neighbor . The faint 9th magnitude red dwarf , currently 63 light-years away in the…
Viewing discoveries from 3 January 2000 through 11 December 1999.