Comet 67P/C-G’s coma fluctuates widely

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Climate change: Data from Rosetta has shown that the coma surrounding Comet 67P/C-G’s nucleus varies far more than had been expected by Earth-based observations.

“From a telescope, images of a comet’s atmosphere suggest that the coma is uniform and does not vary over short periods of hours or days. That’s what we were expecting as we approached the comet,” said Dr. Stephen Fuselier, a director in the SwRI Space Science and Engineering Division and the lead U.S. co-investigator for the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis Double Focusing Mass Spectrometer (ROSINA DFMS) instrument. “It was certainly a surprise when we saw time variations from 200 km away. More surprising was that the composition of the coma was also varying by very large amounts. We’re taught that comets are made mostly of water ice. For this comet, the coma sometimes contains much more carbon dioxide than water vapor.”

The variations might be seasonal, or even reflect a variation from day to night.

Expect more news stories about Comet 67P/C-G from Rosetta. The journal Science is today publishing a special section on results from Rosetta.


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