Nucleus - Coma Gas and dust pouring out from the nucleus...

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Nucleus The Deep Impact spacecraft has been renamed the EPOXI mission . It flew by comet Hartley 2 on November 4, 2010. Hartley 2 is about a quarter the size of Tempel 1. Its two ends are rough and knobbly from which spew jets of carbon dioxide ("dry ice") and a smooth region between the two ends from which frozen water sublimates through the dust. The images were clear enough that astronomers could see jets spewing out from specific surface features and even the "snow" particles in the jets the size of golf balls to basketballs . This is the first comet for which frozen carbon dioxide has provided the jets---usually the jets are made from the sublimation of frozen water. Select the images to go to the websites from where these images came (both images courtesy of NASA/JPL/UMD). The last image in the set compares the sizes of all five of the comet nuclei that have been visited by spacecraft (as of 2010).
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Unformatted text preview: Coma Gas and dust pouring out from the nucleus forms a huge atmosphere around the nucleus. This is the bright core, called a coma , you can see when you observe a comet from the Earth. It is 100,000's of kilometers across. Because the nucleus has such low gravity (you could jump off it!), it cannot hang onto the escaping dust and gas. NASA's StarDust mission captured material from Comet Wild's coma in early Janurary 2004 and returned the microscopic dust grains embedded in aerogel to Earth in mid-January 2006. It found that Comet Wild like Comet Tempel is also made of a mixture of materials with high and low melting temperatures. This may be the result of material originally forming near the Sun that got ejected to the outer parts of the solar system nebula via the bipolar jets we see in many young, forming stars . Further analysis of the Comet Wild material has uncovered Glycine , an amino acid....
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Nucleus - Coma Gas and dust pouring out from the nucleus...

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