Wednesday, 12 August 2009

Another moon/Earth encounter

Many many many years ago - before I started moonwalking - an earth-shattering explosion occured between two celestial bodies, shattering a young earth and creating a young moon. Earth's Moon.

Well, NASA's Spitzer Space Telescope's infrared detectors have recorded a similar collision between two young planets orbiting a young star.

Four billion years ago, a Mars-sized object bashed into Earth, vaporising rock and melting the Earth's surface. A chunk of rock broke away and got caught in orbit around Earth. It became our moon. Today's discovery mimics the Earth/moon encounter - this time one body the size of our moon, the other the size of Mercury. And it all happened just a few thousand years ago!

"The collision that formed our Moon would have been tremendous, enough to melt the surface of Earth," says co-author Geoff Bryden of Nasa's Jet Propulsion Laboratory (JPL) in Pasadena, California.

"Debris from the collision most likely settled into a disc around Earth that eventually coalesced to make the Moon. This is about the same scale of impact we're seeing with Spitzer."

I've decided that if a moon forms this time, I'll head up there and do a moonwalk. Here's hoping.

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