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 interesting molecules like amino acids, the building blocks of life."

Methane, when exposed to intense ultraviolet light like you would find high in the atmosphere of Titan, gets broken down into complex organic molecules. Molecules which might just form the basis for life, if the circumstances are right.

Current climate models show that the depleted methane evaporates in the tropical areas of the planet and are carried by circulation in the atmosphere to the poles. There it cools again and falls down to the surface as rain. In other words, Titan has an evaporation cycle eerily reminiscent to what we have with water. We once even managed to detect this rainfall.

These tropical lakes are likely short-lived, but the first lakes on Titan--first detected in 2004--still remain.

Science Daily Photo by : NASA