> -----Original Message-----
> From: Maser, Donna (SEA) [mailto:[EMAIL PROTECTED]]
>
> I am still waiting/hoping for an answer...
> Why IS there air?
The solar nebula which formed the solar system was composed of a gas cloud rich in volatiles (aka primordial gases). One portion of the this cloud became dense enough to attract by gravitation the particles around it, and hey presto, the sun was formed. As material in the gas cloud surrounding the sun cooled, chunks of rock formed the planets. These chunks of rock, if large enough, would accumulate an atmosphere if the volatile gases surrounding them were cool enough. The escape velocity for Earth is approximately 11 kilometres per second, so any gas molecules passing near the earth at a lower speed would have been captured and remained to form the earth's atmosphere. Additionally, some volatiles adhering to the surface of the solid particles gathering to form the Earth would have been incorporated into the solid planet, and those are occasionally released in the atmosphere by outgassing (e.g. volcanoes, submarine hydrothermal vents). Finally, some people propose that components of the Earth's atmosphere may have been delivered through impact with solid bodies (similar to comets) enriched in volatile materials.
That's only the tip of the iceberg. Should I continue? :-)
(thank you to my high school physics teacher and to Encylopedia Britannica)
------
Jacques R. Kilchoer
(949) 754-8816
Quest Software, Inc.
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Irvine, California 92618
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http://www.quest.com
