Scientific Colloquium
February 11, 2005
The Composite Infrared Spectrometer, on the Cassini orbiter, covers the thermal infrared from 7 mm to 1 mm.  This makes it a very good probe of temperatures (and by extension, of atmospheric winds) and of composition in the Saturn system.  Retrieved atmospheric temperatures on Saturn bear on the question of whether its equatorial winds have slowed down, as suggested by recent HST studies.  Temperatures in Saturn’s rings show structure down to the smallest scales resolved (~100 km) and may provide clues to the rotation rates of the individual particles.  The moons Phoebe and Iapetus have near-surface structure that is fluffier than that of Jupiter’s Galilean satellites.  Titan, with an atmosphere, has a complex chemistry that is perhaps reminiscent of the early earth, and atmospheric winds rotating 10 times faster than its surface.  Its winter pole, which is cold, isolated from low latitudes by a strong circumpolar vortex, and enhanced with organic compounds, may form an analog with the terrestrial Antarctic ozone hole.

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