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.

July 21, 1999
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Galactic Supernova Remnant IC 443
Credit: 2MASS Collaboration, U. Mass., IPAC

Explanation: About 8000 years ago, a star in our Galaxy exploded. Ancient humans might have noticed the supernova as a temporary star, but modern humans can see the expanding shell of gas even today. In the above false-color infrared image of supernova remnant IC 443, blue denotes expanding gas where emission is dominated by excited iron atoms. Of particular interest, though, are the wisps of IC 443 colored red, as they are impacting an otherwise normal molecular cloud. Here emission from shock-excited molecular hydrogen is allowing astronomers to study how fast moving supernova gas affects star formation in the cloud. Additionally, astronomers theorize that the impact accelerates some particles to velocities near the speed of light. The horizontal line across the image is not part of the nebula.

Tomorrow's picture: Cosmic Collisions

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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA)
NASA Technical Rep.: Jay Norris. Specific rights apply.
A service of: LHEA at NASA/ GSFC
& Michigan Tech. U.