By Ron Cowen of Nature magazine A chemical analysis of lunar rocks may force scientists to revise the leading theory for the Moon's formation: that the satellite was born when a Mars-sized body smacked into the infant Earth some 4.5 billion years ago. If that were the case, the Moon ought to bear the chemical signature of both Earth and its proposed 'second' parent. [More]

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Question Arises over Theory that Moon Resulted from Collision with Earth