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.

2000 August 2
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At the Edge of the Crescent Nebula
Credit: Brian D. Moore (ASU) et al., WFPC2, HST, NASA

Explanation: The Crescent Nebula is a rapidly expanding shell of gas surrounding a dying star. In this recently released image by the Hubble Space Telescope, a bright dynamic part of the nebula three light-years across is shown in representative color. The Crescent Nebula began to form about 250,000 years ago as central Wolf-Rayet star WR 136 began to shed its outer envelope in a strong stellar wind, expelling the equivalent of our Sun's mass every 10,000 years. This wind has been impacting surrounding interstellar gas, compacting it into a series of complex shells, and lighting it up. The Crescent Nebula, also known as NGC 6888, lies about 4,700 light-years away in the constellation of Cygnus and can only be seen through a telescope. Star WR 136 will probably undergo a supernova explosion sometime in the next million years.

Tomorrow's picture: 22 Miles From Eros

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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA)
NASA Technical Rep.: Jay Norris. Specific rights apply.
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