A planet that may have helped give the Moon a pummeling huddles close to the Moon tomorrow morning. Jupiter looks like a brilliant star to the lower left of the Moon. They climb into view by about 2 or 2:30, and are high in the sky at first light. And to spice things up a bit, the bright orange star Aldebaran is about the same distance to the lower right of Jupiter.
Earth, the Moon, and the other planets of the inner solar system took a beating from giant asteroids during the solar system’s first half-billion years or so. But a recent study by researchers at the NASA Lunar Science Institute found that it was especially intense at the end of that period — about four billion years ago.
The researchers studied the contours of craters around an ancient volcanic plain. The observations suggest the craters were formed by asteroids that were moving much faster than those that hit the Moon before or after.
The bombardment may have been triggered by changes in the orbits of Jupiter and Saturn. As their distance from the Sun changed, the gravity of the two planets — particularly Jupiter — kicked a group of large asteroids toward the inner solar system. Some of the asteroids then slammed into the Moon and Earth. Wind, rain, and the motions of the crust have erased any traces of this bombardment on Earth, but it’s preserved in the craters of the Moon — the scars of an ancient pummeling.
More about the Moon and its companions tomorrow.
Script by Damond Benningfield, Copyright 2012
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