Jupiter
Jupiter is the largest planet in the Solar System, whose gravity shapes the asteroid belt and steers meteoroids towards Earth.
Jupiter is a giant planet made mostly of hydrogen and helium, more than 11 times Earth's width and over 300 times its mass. It orbits the Sun about every 12 years at roughly five times Earth's distance.
Its gravity has had a huge influence on the asteroid belt. Jupiter's pull probably stopped a planet from forming there and stirred up the asteroids so that they collide at high speed. Where an asteroid's orbit is in step with Jupiter's, called a resonance, repeated tugs stretch the orbit until it crosses the paths of Mars or Earth. This is how many meteorites are delivered: fragments drift into a resonance and are steered our way.
Jupiter may also have formed early and divided the young Solar System into inner and outer parts, explaining the isotopic dichotomy in meteorites. Its gravity both flings some comets towards the inner Solar System and captures or ejects others.
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Level: Beginner Ages 7 and up