Cassini Captures Pictures of Lakes on Titan  The Cassini
spacecraft has managed to grab some remarkable photographs of
tropical lakes on a moon of Saturn. We have known that Titan has
lakes, and even have some photos of a few, but it was believed
that liquid could only stan on the moon at the poles. Tropical
lakes were thought to be impossible.  The photographed lake is
about half the size of the Great Salt Lake in Utah and is at
least 3 feet deep. But it isn't like the lakes we have here on
earth: these are made of liquid methane. The question for
scientists now is, why does this lake exist? Everything that
they know of Titan suggests it shouldn't.  So far the dominant
theory is that the methane comes from an underground aquifer.
"In essence," said Caitlin Griffith, chief author of the paper,
"Titan may have oases."  "An aquifer could explain one of the
puzzling questions about the existence of methane, which is
continually depleted. Methane is a progenitor of Titan's organic
chemistry, which likely produces