Mars, Regulus, and Saturn

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Water is pretty common in our solar system. Icy comets contain lots of water. There's frozen water on Mars, too, and possible oceans of liquid water beneath the crusts of several moons of Jupiter. And liquid water squirts into space from the south pole of one of Saturn's moons.

And there may be an ocean below the crust of another of Saturn's moons, Titan.

Titan is one of the most intriguing bodies in the solar system. It has a thick, cold atmosphere that's topped by a sort of smog. Lakes of liquid methane and ethane appear to dot its surface, and volcanoes may belch more hydrocarbons into the sky.

The Cassini spacecraft has discovered many of these features. And its observations also hint at the subsurface ocean.

In particular, scientists looked at images of different regions of Titan snapped months or years apart. Over time, some distinctive features appeared to move many miles.

The best way to account for the moves is with an ocean about 60 miles below the surface. Different parts of the crust would float on top of the ocean like big rafts, allowing surface features to drift a good distance in a short time. It's just more evidence that water is sprinkled throughout the solar system.

Saturn is in good view tonight. It looks like a bright golden star not far to the upper left of the crescent Moon at nightfall. The true star Regulus is closer to the Moon, almost directly above it.

More about this lineup tomorrow.

Script by Damond Benningfield, Copyright 2008

For more skywatching tips, astronomy news, and much more, read StarDate magazine.