Venusian Volcanoes

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[SFX: volcano; low rumbling; steam hiss]

Venus is a world shaped by volcanoes. Thousands of them cover its surface, and there's evidence that the entire planet was repaved by volcanic eruptions several hundred million years ago. But scientists aren't sure if the ground still moves on Venus today, or if the volcanoes are all extinct.

A spacecraft that's orbiting Venus has found evidence that the volcanoes may still be rumblin'. We can't be sure, though, because no one has ever actually seen an eruption.

The problem is that we can't see the surface of Venus through its unbroken cloud cover. Several orbiting probes have used radar to peer through the clouds and map the surface. But they saw only a tiny piece of the planet at a time.

The new probe, called Venus Express, is studying Venus's atmosphere. And it's seen sharp spikes in the amount of sulfur dioxide -- a gas that's released from volcanoes.

The spikes could mean that volcanoes are erupting on Venus even now. But the sulfur dioxide can remain in the atmosphere for millions of years, so the eruptions could have happened a long time ago. But if that's so, then the sulfur dioxide should be spread pretty evenly, with no big spikes like those observed by Venus Express.

The craft is using other techniques to sniff out volcanoes. Scientists hope that it'll soon let us know whether the ground still moves on our sister world.

More about Venus tomorrow.

Script by Damond Benningfield, Copyright 2008

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