Jupiter, often thought to protect the inner planets from space debris, may sometimes hurl material toward Earth.
According to a popular model of planetary interactions, Jupiter plays an entirely protective role in our solar system, shielding Earth and the other inner planets from space debris.
The long-accepted model indicates that the gravity and location of the giant body in the outer solar system deflects comets and other planetesimals — rubble left over from the planet-making process -- that might otherwise bombard Earth.
But a new set of more detailed simulations suggests that Jupiter can sometimes act like a sniper instead of a shield, hurling material toward Earth. Using a model of some 40,000 planetesimals, Kevin Grazier of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., and his colleagues found that debris in the outer solar system initially had circular orbits and posed no threat to Earth or the other inner planets early in the history of the solar system. But the researchers showed that, thr