If you stepped off a spacecraft onto the surface of Titan, you might experience a little dŽjˆ vu. Saturn’s largest moon has many of the same features as Earth. That includes rivers and seas, clouds, and even rainfall – it’s the only world in the solar system other than Earth with bodies of liquid on its surface.

What wouldn’t seem familiar is the temperature – almost 300 degrees below zero Fahrenheit. In that icebox, water is frozen as hard as granite. So Titan’s rivers and seas and clouds are made of liquid methane and ethane.

Titan is a large world – about half-again the diameter of our moon. And it has the densest atmosphere of any moon in the solar system; the surface pressure is equivalent to a depth of 50 feet in Earth’s oceans.

The methane and ethane are quickly broken apart by sunlight, so the supply in the air has to be renewed. The most likely source is cryo-volcanoes – volcanoes that belch frozen water. Methane mixed with the water would waft into the atmosphere.

The volcanoes could be fed by an ocean of liquid water below the surface – perhaps much more water than in all of Earth’s oceans combined. Both the ocean and the liquid bodies on the surface are possible homes for microscopic life – one more similarity to our own world.

Saturn looks like a bright star near the Moon this evening. Through good binoculars or a small telescope, Titan looks like a tiny star quite near the planet.

Script by Damond Benningfield