THE fiery and turbulent surface of Venus calmed down 750 million years ago, according to a re-analysis of data from the Magellan space probe.
Radar images collected by the orbiter in the early 鈥�90s show several different terrains, but how they formed was unclear. Jim Head of Brown University in Rhode Island and his team focused on meteor craters as a measure of age 鈥� the more pockmarks, the older the terrain.
They conclude that the crust was originally far more mobile, with about a cubic kilometre of lava erupting per year. This is close to the rate at Earth鈥檚 mid-ocean ridges. But about 750 million years ago the crust locked up and eruption volume dropped by a factor of 50 (Geology, vol 30, p 1015).
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