Astronomy Picture of the Day
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
2003 October 16 
Posted on 10/16/2003 5:41:29 AM PDT by petuniasevan
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
2003 October 16
Explanation: NGC 6888, also known as the Crescent Nebula, is a cosmic bubble of interstellar gas about 25 light-years across. Created by winds from the bright, massive star seen near the center of this composite image, the shocked filaments of gas glowing at optical wavelengths are represented in green and yellowish hues. X-ray image data from a portion of the nebula viewed by the Chandra Observatory is overlaid in blue. Such isolated stellar wind bubbles are not usually seen to produce energetic x-rays, which require heating gas to a million degrees celsius. Still, NGC 6888 seems to have accomplished this as slow moving winds from the central star's initial transition to a red supergiant were overtaken and rammed by faster winds driven by the intense radiation from the star's exposed inner layers. Burning fuel at a prodigious rate and near the end of its stellar life, NGC 6888's central star should ultimately go out with a bang, creating a supernova explosion in 100,000 years or so. NGC 6888 is about 5,000 light-years close, toward the constellation Cygnus.
NGC 6888 the Crescent Nebula in Cygnus
| Right Ascension: | 20 : 12.0 (hours : minutes) |
|---|---|
| Declination: | +38 : 21 (degrees : minutes) |
| Apparent Magnitude: |
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| Apparent Diameter: | 20. (arc minutes) |
The central star is a Wolf-Rayet star, named for the discoverers of stars of this spectral type. They are VERY hot, blue, massive, and luminous. Instability and the shedding of stellar material are hallmarks. So is a Wolf-Rayet star's natural laser. What, you say? LASER stars??? Yes indeed. For more information (fascinating), visit THIS LINK.
Titan 2 rocket to launch military satellite Thursday
The final Titan 2 rocket will try again Thursday to launch the long-delayed Defense Meteorological Satellite Program F16 spacecraft on a $450 million mission to monitor weather conditions around the globe for U.S. military forces. Wednesday's launch attempt from Vandenberg Air Force Base in California was scrubbed. Check our status center for ongoing coverage.
MISSION STATUS CENTER - live updates!
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