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.

2005 September 15
See Explanation.  Clicking on the picture will download
 the highest resolution version available.

The Nucleus of Comet Tempel 1
Credit: Univ. Maryland, JPL-Caltech, NASA

Explanation: Approaching the nucleus of comet Tempel 1 at ten kilometers per second, the Deep Impact probe's targeting camera recorded a truly dramatic series of images. Successive pictures improve in resolution and have been composited here at a scale of 5 meters per pixel -- including images taken within a few meters of the surface moments before the July 4th impact. Analyzing the resulting cloud of debris, researchers are directly exploring the makeup of a comet, a primordial chunk of solar system material. Described as a recipe for primordial soup, the list of Tempel 1's ingredients - tiny grains of silicates, iron compounds, complex hydrocarbons, and clay and carbonates thought to require liquid water to form - might be more appropriate for a cosmic souffle, as the nucleus is apparently porous and fluffy. Seen here, Tempel 1's nucleus is about five kilometers long, with the impact site between the two large craters near the bottom.

Tomorrow's picture: pixels in space

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