News Focus

Impact Theory Gets Whacked

See allHide authors and affiliations

Science  11 Oct 2013:
Vol. 342, Issue 6155, pp. 183-185
DOI: 10.1126/science.342.6155.183

You are currently viewing the summary.

View Full Text

Log in to view the full text

Log in through your institution

Log in through your institution


Where did the moon come from? For 3 decades, planetary scientists have agreed that it happened something like this: While the solar system was still forming, a body the size of Mars struck Earth a glancing blow that reduced both to rubble. The cloud of debris reformed itself into the modern Earth and moon. This "giant impact" theory neatly explained why the rocks Apollo astronauts brought back from the moon closely resembled rocks on Earth—or so it seemed at first. Actually, recent computer models show, such a collision wouldn't have scrambled the two bodies together enough to explain the similarity. Meeting last month in London to discuss the problem, scientists agreed that the origin of the moon must have been messier and more complicated than anyone had assumed.