The "hot Jupiter" planet Wasp 18 orbits its parent star in this artist's concept. Hot Jupiters are giant worlds similar to Jupiter, the largest planet in our own solar system, but much closer to their parent stars, so they are extremely hot. Such planets probably were born much farther out, then migrated inward to their current positions. [NASA/CXC/SAO/I.Pillitteri et al]
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Moon and Jupiter
“Hot Jupiters” aren’t very friendly. Few of the giant planets have nearby companion planets. That could mean that the hot Jupiters have kicked other planets away.
Hot Jupiters were the first planets discovered in other star systems. They’re big, heavy balls of gas, like Jupiter, the giant of our own solar system. But while Jupiter is far from the Sun, hot Jupiters are quite close in, so they’re heated to hundreds or thousands of degrees.
Such planets can’t form that close to a star — it’s just too hot. They must have been born farther out, then moved inward. The question is whether that’s a gentle process, allowing the Jupiter to co-exist with other planets, or a more violent one that boots the other planets out of its way. And so far, the “violent” scenario has been the most likely, because astronomers have found few close companion planets.
But in a recent study, about one in eight hot Jupiters did have a nearby companion. Those Jupiter-like worlds must have migrated inward in the gentler process, sparing their sibling worlds. And warm Jupiters — those that are a little farther out — were more hospitable: about two-thirds had close companions. So there may be more than one way for a Jupiter to fall toward its parent star.
Our own Jupiter teams up with the Moon the next few nights. It looks like a brilliant star. It’s well to the lower left of the Moon tonight, but will huddle much closer tomorrow night.
Script by Damond Benningfield