Browse NASA Astronomy Picture of the Day archive by date and media: Archive Discoveries
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The Millennium that Defines Universe
Welcome to millennium three . During millennium two , humanity continually redefined its concept of “Universe”: first as spheres centered on the Earth , in mid-millennium as the…
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…
A Year of Resolving Backgrounds
No matter which direction you look, no matter what type of light you see, the sky glows - but why? The sources of many of these background radiations have remained long-standing…
The Dark Horsehead Nebula
While drifting through the cosmos this magnificent interstellar dust cloud, sculpted by stellar winds and radiation, has chanced to assume a recognizable shape. Fittingly named…
Moon Mare and Montes
This arresting image of the third quarter moon in the excellent skies above the Pine Crest Farm Observatory, Dell Prairie, Wisconsin, was recorded with a 24 inch telescope and…
The Dust and Ion Tales of Comet Hale-Bopp
In 1997, Comet Hale-Bopp 's intrinsic brightness exceeded any comet since 1811 . Since it peaked on the other side of the Earth's orbit, however, the comet appeared only brighter…
Jupiter, Io, and Shadow
Just as planets orbit our Sun, Jupiter's Moons orbit Jupiter. Pictured above is the closest of Jupiter's Galilean Satellites , Io , superposed in front of the giant planet it…
The Eclipse Tree
If you look closely at the shadow of this tree, you will see something quite unusual: it is composed of hundreds of images of a partially eclipsed Sun . Early today , trees across…
NGC 1850: Gas Clouds and Star Clusters
There's nothing like it in our own Galaxy . Globular clusters as young as NGC 1850 don't exist here. Globular clusters only 40 millions of years old can still be found in the…
Summer at the South Pole
The December solstice brings the beginning of Winter to Earth's Northern Hemisphere and Summer time to the South! This view of Earth's Southern Hemisphere near the beginning of…
Simulated Supergiant Star
Looking for that perfect holiday gift for an astronomer? Consider this “star in a box”. Of course, the box is actually a computational box consisting of a three dimensional grid…
Solstice And Season's Eclipse
Today the Sun reaches its southernmost point in planet Earth's sky at 13:37 UT . This celestial event is known as a solstice, marking the beginning of Summer in the Southern…
Sgr A*: Fast Stars Near the Galactic Center
Why are these stars moving so fast? Shown above is a time-lapse movie in infrared light detailing how stars in the central light-year of our Galaxy have moved over the past eight…
A Close-Up of Aurora on Jupiter
Jupiter has aurorae . Like Earth , the magnetic field of the gas giant funnels charged particles released from the Sun onto the poles. As these particles strike the atmosphere,…
Oceans Under Jupiter's Moon Ganymede?
The search for extraterrestrial life came back into our own Solar System last week with the announcement that there may be liquid oceans under the surface of Jupiter 's moon…
M2-9: Wings of a Butterfly Nebula
Are stars better appreciated for their art after they die? Actually, stars usually create their most artistic displays as they die. In the case of low-mass stars like our Sun and…
Degas Ray Crater on Mercury
Like the Earth's Moon, Mercury is scarred with craters testifying to an intense bombardment during the early history of the Solar System. In 1974, the Mariner 10 spacecraft…
IC443's Neutron Star
Using x-ray data from the orbiting Chandra Observatory along with radio data from the Very Large Array , a team of researchers has discovered evidence for a new example of one of…
International Space Station Trail
Still under construction, the International Space Station is becoming one of the brightest , fastest moving “stars” in the heavens. Despite illuminated clouds and bright light…
Manicouagan Impact Crater on Earth
The Manicouagan Crater in northern Canada is one of the oldest impact craters known. Formed during a surely tremendous impact about 200 million years ago, the present day terrain…
Jupiter Eyes Ganymede
Who keeps an eye on the largest moon in the Solar System ? This moon, visible on the lower right, is Ganymede , and the planet it orbits, Jupiter , seems to be keeping a watchful…
Composing the Omega Nebula
The Omega Nebula is a massive, complex cloud of dust and gas from which new stars are continually forming. The similarity to the Greek letter capital Omega gives the molecular…
Too Close to a Black Hole
What would you see if you went right up to a black hole ? Above are two computer generated images highlighting how strange things would look. On the left is a normal star field…
Apollo 17 Lunarscape: A Magnificent Desolation
Buzz Aldrin , Apollo 11 Lunar Module pilot and the second human to walk on the Moon , described the lunar landscape as “a magnificent desolation”. Dramatic pictures from the…
Viewing discoveries from 1 January 2001 through 9 December 2000.