Even though Jupiter is, on average, half a billion miles from Earth, its strong gravity may have played a profound role in the development of life on Earth. Jupiter pulls all kinds of matter toward itself with its gravity, including comets and asteroids. Had Earth been bombarded with too many comets and asteroids over the past four billion years, life on Earth might not have had a chance to develop and evolve as it has. Jupiter has acted like a gravitational shield, absorbing large numbers of cosmic projectiles that otherwise might have caused serious blows to life on Earth.