Is Jupiter Earth's Friend or Foe?

Is Jupiter a friendly planet, Earth's enemy, or perhaps both? For decades, scientists have talked about how the giant gas planet keeps some asteroids from striking our small world, while others have pointed out that Jupiter's gravity could send some civilization-shattering asteroids our way.

While that debate goes on, a subtler question arises about how influential Jupiter was in the early Solar System. Jupiter is by far the heavyweight planet in the Solar System, weighing in at 320 Earth masses. Its gravity not only influences small asteroids that go by, but also tugs on other planets in the solar system – including our own. Read more...