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 July 3
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Pelican Nebula Ionization Front
Credit: John Bally (U. Colorado), KPNO 0.9-m Telescope, NOAO, AURA, NSF

Explanation: The Pelican Nebula is slowly being transformed. IC 5070, the official designation, is divided from the larger North America Nebula by a molecular cloud filled with dark dust. The Pelican, however, receives much study because it is a particularly active mix of star formation and evolving gas clouds. The above picture was produced in two specific colors to better understand these interactions. Here, hot hydrogen gas glows in red, while cooler Sulfur glows blue-green. The light from young energetic stars is slowly transforming the cold gas to hot gas, with the advancing boundary between the two known as an ionization front. Particularly dense filaments of cold gas are seen to still remain. Millions of years from now this nebula might no longer be known as the Pelican, as the balance and placement of stars and gas will leave something that appears completely different.

Tomorrow's picture: Comet LINEAR Approaches

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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA)
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