German scientists studied moon rocks gathered by astronauts nearly a half-century ago in the Apollo 11, 12 and 16 missions. They analyzed various kinds of oxygen atoms and found the moon rocks have a different makeup than Earth rocks do. That fits with the idea that the moon would contain material from the object that struck Earth.
The results also suggest that the moon may be a 50-50 mix of material from this object and from Earth.
The study was published Thursday by the journal Science.
Online: Science journal: http://www.sciencemag.org/
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