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This image is a schematic of a comet. The center part of the comet, or nucleus, is represented by the flame. The solar wind particles are shown as green dots with arrows. And the ionized particles are shown as green/red dots with arrows. Neutral particles are shown by the other dots (without arrows).
Click on image for full size
JPL

The Comet Coma

As the ices of the comet nucleus evaporate, they expand into a large cloud around the middle part of the comet.

This cloud, called the coma, is the atmosphere of the comet. It can extend for millions of miles. The cloud is very thin, 10,000 times thinner than a cloud in the Earth's atmosphere!

Last modified November 10, 2003 by Jennifer Bergman.

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Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA