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Astronomy Picture Of the Day (APOD)
Cocoon of a New White Dwarf
3.12.1996
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 ejected shell of gas would become the prettiest of all!
Orion's Star Colors
2.12.1996
What determines a star's color? Its temperature. Red stars are cool, with temperatures of around 3,000 degrees Kelvin (K), while blue stars are hotter and can have temperatures over 30,000 degrees K. Our own lovely yellow Sun's temperature is a comforting 6,000 degrees K.
Star Trails in Northern Skies
1.12.1996
As the Earth spins on its axis, the sky seems to rotate around us. This motion produces the beautiful concentric arcs traced out by the stars in this time exposure of the night sky.
Aurora Astern
30.11.1996
Sailing upside down, 115 nautical miles above Earth, the crew of the Space Shuttle Endeavour made this spectacular time exposure of the southern aurora (aurora australis) in October of 1994. The aurora, also known...
Io: The Fissure King?
29.11.1996
Is Io the solar system's Fissure King? Well, probably not ... but it is the most active volcanic moon. Active volcanoes on Jupiter's moon Io were a surprise discovery of the Voyager missions of the late 1970s.
Comet-like Clouds in the Cartwheel Galaxy
28.11.1996
In a cartwheel-shaped galaxy far, far away, huge comet-shaped clouds of gas have been discovered racing through the nucleus at about 700,000 miles per hour. The aptly named Cartwheel Galaxy is actually about 500 million light years distant, its suggestive shape created by a head-on collision with a smaller galaxy.
Storm Clouds Over Jupiter
27.11.1996
Storm clouds, similar to the familiar cumulonimbus thunderheads of Earth, appear to be present on Jupiter. The mosaic of images above shows the region near the raging edge of Jupiter's Great Red Spot, itself some 2 to 3 Earths wide, as observed by the Galileo spacecraft in June of this year.
The Radio Sky: Tuned to 408MHz
26.11.1996
Tune your radio telescope to 408MHz (408 million cycles per second) and check out the Radio Sky! You should find that frequency on your dial somewhere between US broadcast television channels 13 and 14.
A Quasar Portrait Gallery
25.11.1996
QUASARs (QUASi-stellAR objects) lie near the edge of the observable Universe. Discovered in 1963, astronomers were astounded - to be visible at such extreme distances of billions of light-years they must emit prodigious amounts of energy. Where does the energy come from?
Apollo 12 Visits Surveyor 3
24.11.1996
Apollo 12 was the second mission to land humans on the Moon. The landing site was picked to be near the location of Surveyor 3, a robot spacecraft that had landed on the moon three years earlier. Pictured above, Apollo 12 astronauts Conrad and Bean retrieve parts from the Surveyor.
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