Titan's Dark Mirror
http://sciencenow.sciencemag.org/cgi/content/full/2007/218/2
SAN FRANCISCO, CALIFORNIA--What can Saturn's largest moon tell us
about our own planet's future? Quite a lot, apparently, researchers
told the annual meeting of the American Association for the
Advancement of Science (which publishes ScienceNOW) today. In a
presentation here, scientists poring over data from the Cassini
spacecraft and ground-based observations painted close parallels
between the evolution of Earth and the climate and geology of Titan.
For a body more than a billion kilometers away, Titan has a
surprisingly lot in common with Earth. Its atmosphere--while roughly
four times denser and 10 times thicker than Earth's--is dominated by
nitrogen, just like ours is. Instead of water vapor as an atmospheric
constituent, Titan has methane, but it behaves just as water vapor
does in Earth's air. Titan has weather, too. Planetary scientist
Jonathan Lunine of the University of Arizona in Tucson explains that
during a cycle taking up to 100 years, methane on Titan's surface
slowly evaporates into the atmosphere and migrates toward the polar
regions, where it falls in brief but torrential downpours, carving
deep channels into the moon's surface and filling lakes as wide as
100 kilometers.
See: http://sciencenow.sciencemag.org/cgi/content/full/2007/218/2
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