GOOD NIGHT, TWO MOONS?

EARTH'S LONELY SATELLITE MIGHT HAVE HAD A SISTER

The cow probably had a hard enough time jumping over one moon, never mind two. Yet there is a good chance, according to a new paper appearing in the journal Nature, that the moon we know so well once had a sister.

Astronomers are not sure how our moon was formed, but increasingly they have come to suspect it was born in violence, blasted away from Earth by a collision with a planet-like object at least as big as Mars. To test this theory, a research team from Tokyo University and the University of Colorado, Boulder, developed a computer program that...

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