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Water Worlds: Titan

September 25, 2012

The deepest spot on Earth is the Challenger Deep — a part of the Mariana Trench that lies seven miles below the surface of the Pacific Ocean. But that’s just barely a wading pool compared to a possible ocean on Titan, the largest moon of Saturn. It could be up to 150 miles deep, and hold far more water than Earth’s oceans.

Titan is enveloped in a cold, thick atmosphere that’s topped with an organic haze — a sort of smog. Lakes of liquid methane and ethane dot its surface. But recent observations suggest there’s far more liquid beneath Titan’s crust, which is made largely of frozen water.

Over the last few years, scientists have used the Cassini spacecraft to measure how much the surface of Titan flexes — the result of tides caused by the gravitational pull of Saturn. They found that the tides are about 30 feet high — much higher than if Titan were made just of rock.

So instead, it must be made of about a 60-40 combination of rock and water. Some of the water makes up the frozen crust, but much of it must still be liquid — warmed by the energy of the tides and the decay of radioactive elements inside Titan.

The scientists haven’t measured the size of the ocean. But they suspect it begins perhaps 50 miles down, and could be 150 miles deep. If so, then it contains about four billion cubic miles of water — more than a dozen times more water than all of Earth’s oceans combined.

We’ll talk about another water world tomorrow.


Script by Damond Benningfield, Copyright 2012

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