...[the] moon actually prevents space collisions with the earth (Comins, 1991). Many space rocks that would otherwise hit the earth are instead drawn to the moon by its gravity attraction. The far side of the moon, exposed to incoming objects, is especially heavily cratered. Some of these lunar craters are over 150 miles (241 km) in diameter. Such large impacts on Earth could cause profound changes in the earth's atmosphere and climate.
On a larger scale, the planet Jupiter also protects the earth from collisions with asteroids and comets. Jupiter's mass is greater than the other eight planets combined. As a result, Jupiter has a large attractive gravity force for objects approaching the inner solar system.In 1994 astronomers watched fragments from Comet Shoemaker-Levy strike Jupiter. The approaching comet broke up when it crossed within Jupiter's Roche limit.... Two dozen separate impact collisions then occurred on Jupiter, each one much more energetic than a nuclear blast. Had any of the comet fragments hit the earth, a crater at least 50 miles in diameter would have resulted.
Friday, June 4, 2010
From Our Created Moon: Earth's Fascinating Neighbor by Don DeYoung & John Whitcomb (page 56):