COULD blasts of gas from deep beneath the lunar surface be giving the moon a surprisingly fresh-faced look? If they are, our picture of the moon鈥檚 geological past will have to change just as dramatically.
The moon was thought to be geologically inactive. The last volcanoes erupted on it nearly a billion years ago, and meteor impacts were believed to be the only thing that could be altering its surface. That belief is set to change.
Carle Pieters of Brown University in Providence, Rhode Island, and her colleagues studied images from the Apollo missions of the 1960s and 鈥�70s along with spectrographic readings from more recent space probes.
Advertisement
The team focused on the Ina structure, an unusual-looking area nearly 3 kilometres in diameter near the moon鈥檚 equator. It has fewer craters, sharper topography, and is far brighter than the surrounding surface. This 鈥渇reshness鈥� suggests it has not been suffered many major impacts or much weathering by solar wind and microscopic meteors, which can dull and blunt surface features (Nature, vol 444, p 184).
The researchers think that the fresh features were created when gas emissions blew off a previous layer of rock to expose a fresh surface as recently as 10 million years ago 鈥� a phenomenon that could still be under way. 鈥淭he freshness of these surfaces is hard to account for in any other way,鈥� says Pieters.
