Earth vaporised and the moon then sprang out

摘要

A SHAPE-SHIFTING Earth might have formed the moon. Roughly 4.5 billion years ago, a collision made our planet mushroom outward into a spinning cloud of vaporised rock resembling a squished jam doughnut. At its puffy edges the moon formed, suggests new work on a model of early Earth. Scientists have long suspected that a Mars-sized body known as Theia struck the young Earth, throwing molten rock into orbit. It would have coalesced into a moon mostly made of material from Theia, but Apollo moon rocks suggest that its make-up is almost identical to Earth's.