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The Hydrogen Clouds of Comets

Published online by Cambridge University Press:  12 April 2016

Mikio Shimizu
Mikio Shimizu*
Affiliation:
ISAS, Sagamihara Kanagawa 229, Japan

Abstract.

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In a cometary coma, various hydrogen compounds, especially water, that are photodissociated by solar ultraviolet radiation form a gigantic hydrogen cloud with a radius of several million kilometers around the cometary nucleus. These cometary hydrogen clouds have been observed by a number of spacecraft outside the terrestrial atmosphere and in interplanetary space. For instance, the hydrogen cloud of Comet Halley was a good target for the ultraviolet photometers and spectrometers on board the International Ultraviolet Explorer (IUE), Suisei, Pioneer Venus, DE-1, and sounding rockets. Hydrogen cloud activity could be used as a good measure of cometary activity, but some problems remain to be explored in the future.

Type
Section V: The Cometary Coma
Information
International Astronomical Union Colloquium , Volume 116 , Issue 2: Comets in the Post-Halley Era , 1991 , pp. 897 - 905
Copyright
Copyright © Kluwer 1991

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