The giant volcano Sapas Mons sprawls across hundreds of square miles of Venus in this false-color view from the Magellan orbiter, which used radar to peer through the planet's clouds. The volcano is about 250 miles wide and one mile tall. Lava flows coat its flanks, including the relatively smooth dark patch to the lower right of its summit, and rougher, lighter flows all around it. There's evidence that some of Venus's volcanoes could be active today, although none has ever been seen erupting. [NASA/JPL]
Two worlds that are coated with volcanic rock huddle close together in the western sky after sunset. Venus, the “evening star,” stands just to the left of the crescent Moon.
The Moon’s volcanic rock is easily visible — it forms the dark features known as mare. These features all formed about four billion years ago, when giant asteroids slammed into the lunar surface, gouging out wide, deep basins. Molten rock bubbled up from below the surface to fill them.
There are no active volcanoes on the Moon, although there are some extinct ones. There are hints of some volcanic activity, though. Faint flashes of light and haziness have been reported around some features — possible outbursts of gas from beneath the lunar surface.
Venus is coated with volcanic rock as well, but it’s much younger. There’s evidence that the surface was completely repaved by molten rock about 700 million years ago. So far, though, no one is sure why that happened.
And no one has seen an active volcano on Venus, either. In part, that may be because we can’t see the surface through the planet’s thick clouds. The only good views have come from spacecraft in orbit around Venus that use radar to peer through the clouds.
There’s some evidence that Venus could still have active volcanoes, though. There are traces of volcanic gases in the atmosphere, and some of the volcanoes seen with radar are coated with fairly fresh material — possible outflows of new volcanic rock.
Script by Damond Benningfield, Copyright 2013
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