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Astronomy Picture Of the Day (APOD)
IC 4406: A Seemingly Square Nebula
27.04.1998
How can a round star make a square nebula? This conundrum came to light with the discovery of planetary nebulae like IC 4406. IC 4406 is most probably cylindrical, with its square appearance the result of our vantage point in viewing the cylinder.
NGC 2440: Cocoon of a New White Dwarf
26.04.1998
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!
Supernova Remnant and Neutron Star
25.04.1998
A massive star ends life as a supernova, blasting its outer layers back to interstellar space. The spectacular death explosion is initiated by the collapse of what has become an impossibly dense stellar core. However, this core is not necessarily destroyed.
Infrared Saturn
24.04.1998
This delightfully detailed false color image of Saturn has been earmarked to celebrate the 8th anniversary of the orbiting Hubble Space Telescope. The picture is a combination of three images taken in January of this year with the Hubble's new NICMOS instrument and shows the lovely ringed planet in reflected infrared light.
Three Dusty Stars
23.04.1998
These separate radio images reveal three dusty debris disks surrounding three bright, young, nearby stars - evidence for solar systems in formation. From left to right are the stars Fomalhaut, Beta Pictoris, and Vega, their positions indicated by star symbols. The false color maps show the intensity of submillimeter radio emission from the surrounding dust.
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.
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