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Astronomy Picture Of the Day (APOD)
HR 4796A: A Recipe for Planets
22.04.1998
Two hundred and twenty light years from Earth, planets are forming. Recent observations of the binary star system HR 4796 have shown that one of the stars is surrounded by a dusty gaseous disk. This disk is of the right size, age, and density for dust pellets to accrete surrounding matter.
Water From Orion
21.04.1998
Is Orion all wet? Recent observations have confirmed that water molecules now exist in the famous Orion Nebula, and are still forming. The Orion Nebula (M42, shown above) is known to be composed mostly of hydrogen gas, with all other atoms and molecules being comparatively rare.
Name This Satellite
20.04.1998
Can you name this satellite? In December, NASA's third Great Observatory is planned for launch. The two NASA Great Observatories currently in orbit are the Hubble Space Telescope and the Compton Gamma-Ray Observatory, both now named for famous scientists. But after whom should the Advanced X-ray Astrophysics Facility (AXAF) be named?
Betelgeuse
19.04.1998
Here is the first direct picture of the surface of a star other than our Sun. Taken by the Hubble Space Telescope in 1995, the atmosphere of Betelgeuse reveals some unexpected features, including a large bright hotspot visible below the center.
Star Wars in NGC 664
18.04.1998
Long ago in a galaxy far, far away, locked in their final desperate struggle against the force of gravity ... two stars exploded! stellar explosions - Supernovae - are among the most powerful events in the Universe, estimated to release an equivalent energy of up to 1 million trillion trillion (1 followed by 30 zeros) megatons of TNT.
Mars: Looking For Viking
17.04.1998
On July 20, 1976, the Viking 1 lander touched down on the Martian Chryse Planitia. Its exact landing site is somewhere in the white rectangle above. Unfortunately, this wide angle Mars Global Surveyor image...
Mars: Cydonia Close Up
16.04.1998
The Mars Global Surveyor spacecraft has returned another close-up of the Cydonia region on Mars. Orbiting over clear Martian skies at a range of about 200 miles, the Mars Orbiter Camera looked down...
NGC 1818: Pick A Star
15.04.1998
This is NGC 1818, a youthful, glittering cluster of 20,000 stars residing in the Large Magellanic Cloud, 164,000 light-years away. Pick a star. Any star. Astronomers might pick the unassuming bluish-white one (circled) which appears to be a hot newly formed white dwarf star. What makes it so interesting?
Starlight Reflections
14.04.1998
Wisps of dust fill the space between the stars. This dust is usually invisible, subtly acting to dim the light of more distant stars. Sometimes this dust is thick and prominent as dark patches on otherwise bright emission nebulae. Other times this dust may show itself by reflecting the light of bright, nearby stars.
The Sun Changes
13.04.1998
Our Sun changes every day. This recent picture was taken in a very specific red color called Hydrogen-Alpha. Dark spots that might appear on the image are usually sunspots, dark magnetic depressions that are slightly cooler than the rest of the Sun's surface.
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