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Monday, November 23, 2009

Photo: Moon Has Iron Core, Lunar-Rock Study Says


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How did the moon form? The "big whack" theory suggests that a Mars-size object slammed into the hot early Earth. The debris that was ejected went into Earth's orbit and gradually came together, forming the moon, the widely accepted theory says.

A new lunar-rock study suggests that the moon's insides are a lot like Earth's—new evidence that the theory of the big whack is on the right track.

Illustration courtesy NASA