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It's raining natural gas

Credit: NASA/JPL/Space Science Institute

On Saturn's biggest moon, infrequent but heavy downpours of liquid natural gas have created steep-sided valleys and flushed icy debris and dark goo into shallow lakes.

Scientists' understanding of these kinds of activities on this moon, Titan, took a giant leap forward after the European Space Agency's little explorer was ejected from the Cassini spacecraft and landed on this hazy moon, early in 2005.

This explorer, called the "Huygens" probe, detected canyons, riverbeds, plains, rocks and possible lakes and seas on the surface of Titan.

Later in 2005, scientists detected clouds around the moon's midsection popping up like smoke from a chimney and then raining out their liquid natural gas as they blow downwind, according to a news story in the journal Science.

These kinds of observations highlight interesting similarities between the water cycle that is so critical to life here on Earth and the liquid natural gas or "liquid methane" cycle on Titan.

In a new study in the 13 January 2006 issue of the journal Science, scientists describe a series of complex simulations or "models" whose cloud predictions are quite similar actual observations of clouds on Titan.

Unlike Earth's clouds, which are mostly made of water, the clouds on Titan are made of natural gas.

The fact that the new model and real-world observations match up is a good sign because it means that scientists' ideas about what causes the clouds to form seem to be getting more and more accurate.

These kinds of models may lead scientists to new discoveries about how clouds form on Titan, according to Pascal Rannou from Université de Versailles-St-Quentin in Verrieres le Buisson, France and his colleagues.