Man in the Moon’s violent birth

Astronomers have discovered what caused the “man in the moon” – a collision with giant asteroids.

The space rocks smashed into the far side of the moon, which is never visible from Earth, billions of years ago. They left a huge dent and the shock waves pushed out a bulge in the side of the moon facing us.

Impact damage caused the moon’s surface to crack and molten lava flooded out to create the lunar seas – huge grey plains that form the familiar “face” on our natural satellite. Planet experts at Ohio State University discovered evidence for the collisions using data from two NASA satellites orbiting the moon, Clementine and Lunar Prospector.

Early Apollo missions had shown that the moon had an Earth-facing bulge plus a large depression on the far side. But previously they believed these were due to the Earth’s gravity tugging on the moon in the early days of the solar system.

The new research, published by Laramie Potts and Ralph von Frese in the journal Physics of the Earth and Planetary Interiors, shows that part of the moon’s crust still juts into its core, 700 miles below the surface, because of the catastrophic impacts.

Astronomers say the finding holds implications for lunar prospecting, and may solve a mystery about how past impacts on Earth affect its geology today.

© Paul Sutherland. Unauthorised reproduction forbidden.

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