Slide 20 of 49

The Solar System is unique in that the rocky inner planets are protected from cometary bombardment by two large gas giants. Scientists estimate that the Earth would receive approximately 10,000 times its current level of comet impacts if these planets were not where they are. So, instead of suffering catastrophic collisions every 100 million years, the earth would be suffering those collisions every 10,000 years in the absence of the planet Jupiter. Such a large number of collisions would have prevented the existence of life on the Earth.