Jupiter leads the Moon across the sky tonight like a dog on a leash. And it’s a dog with a big bite. The planet had a big influence on the formation of the other worlds of the solar system — perhaps even the Moon.

Jupiter is heavier than all the other planets and moons in the solar system combined. That gives it a strong gravitational pull. And that’s the key to its effect on other worlds.

When the solar system was young, Jupiter probably moved closer to the Sun, then back out again. Its gravity may have cleared out much of the planet-making material closer to the Sun. Studies say Jupiter could have pushed many asteroids out of the asteroid belt and stirred up the ones that remained, keeping them from forming a planet.

Jupiter also may have cleared out material in the region that was giving birth to Mars. That kept the planet small — about half the size of Earth.

And a recent study said that, although it’s unlikely, Jupiter could have helped create the Moon. It could have moved toward the Sun fairly quickly, pushing things around in the inner solar system. That could have caused a collision between Earth and another planet — perhaps one as big as the original Earth. The impact destroyed both planets. But the debris might have reassembled to form Earth and the Moon — part of the influence of a giant.

Jupiter stands to the upper right of the Moon at nightfall, and looks like a brilliant star.

Script by Damond Benningfield

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