Pamela Rwanyarare in Uganda writes ‘Is it true that Jupiter is our friendliest planet because it is argued that there were asteroids and meteorites that could have hit us – but we have not been hit because, before they get to Earth, they are pulled in by Jupiter?’
Yes. Jupiter’s gravity does help protect Earth.
Jupiter is our solar system’s largest planet. And it creates both good and bad conditions for earthly life. On the one hand, Jupiter’s powerful gravity prevented space rocks orbiting near it from coalescing into a planet, and that’s why our solar system has an asteroid belt. Today, Jupiter’s gravity continues to affect the asteroids – only now it nudges them toward the sun, where they have the possibility of colliding with Earth.
On the other hand, Jupiter’s gravity also protects us. Long-period comets enter the solar system from its outer reaches. Jupiter’s gravity slings most of these fast-moving ice balls out of the solar system before they can get close to Earth. So long-period comets are thought to strike Earth only about every 30 million years. Without Jupiter nearby, long-period comets would collide with our planet up to 1000 times more frequently.