These side-by-side false-color images show Saturn's heat emission. The
data were taken on Feb. 4, 2004, from the W. M. Keck I Observatory, Mauna
Kea, Hawaii. Both images were taken with infrared radiation. The image on
the left was taken at a wavelength near 17.65 microns and is sensitive to
temperatures in Saturn's upper troposphere. The image on the right was
taken at a wavelength of 8 microns and is sensitive to temperatures in
Saturn's stratosphere. The prominent hot spot at the bottom of each image
is at Saturn's south pole. The warming of the southern hemisphere was
expected, as Saturn was just past southern summer solstice, but the abrupt
changes in temperature with latitude were not expected.
The troposphere temperature increases toward the pole abruptly near 70
degrees latitude from 88 to 89 Kelvin (-301 to -299 degrees Fahrenheit)
and then to 91 Kelvin (-296 degrees Fahrenheit) right at the pole. Near
70 degrees latitude, the stratospheric temperature increases even more
abruptly from 146 to 150 Kelvin (-197 to -189 degrees Fahrenheit) and
then again to 151 Kelvin (-188 degrees Fahrenheit) right at the pole.
While the rings are too faint to be detected at 8 microns (right), they
show up at 17.65 microns. The ring particles are orbiting Saturn to the
left on the bottom and to the right on the top. The lower left ring is
colder than the lower right ring, because the particles are just moving
out of Saturn's shadow where they have cooled off. As they orbit Saturn,
they warm up to a maximum just before passing behind Saturn again in
shadow.
