Researchers at the California Institute of Technology, NASA's
Jet Propulsion Laboratory, and other institutions suggest that
the eccentricity of Saturn's orbit around the sun may be
responsible for the unusually uneven distribution of lakes over
the northern and southern polar regions of the planet's largest
moon, Titan. A paper describing the theory appears in the Nov.
29 advance online edition of Nature Geoscience. Saturn's oblong
orbit around the sun exposes different parts of Titan to
different amounts of sunlight, which affect cycles of
precipitation and evaporation in those areas. Similar variations
in Earth's orbit also drive long-term ice-age cycles on our
planet. As revealed by Synthetic Aperture Radar imaging data
from NASA's Cassini spacecraft, liquid methane and ethane lakes
in Titan's northern high latitudes cover 20 times more area than
lakes in the southern high latitudes. The Cassini data also show
there are significantly more partially filled and now-empty
lakes in the north. (In the radar da