Wacky Planet Has 3 Sunrises, 3 Sunsets Each Day

Or else it spends 140 Earth-years in daylight
By Arden Dier,  Newser Staff
Posted Jul 8, 2016 11:13 AM CDT

Don't let aliens from HD 131399Ab hear you complaining about global warming. The newly discovered planet 340 light-years from Earth in the constellation Centaurus is the first found to be orbiting three suns and is scorching at 1,000 degrees—though that's mostly because of its gas formation. Discovered by astronomers using a special tool to detect the heat signatures of young planets, HD 131399Ab is actually twice as far from its sun as Pluto is from ours. Two other stars circling each other orbit the same sun from much farther away. That means that for about half of the planet's orbit, it enjoys three sunrises and sunsets on each of its days. But that's only part of why coming up with a calendar for the planet would be a real challenge, reports CNET. It takes 550 Earth-years for it to complete an orbit, so its seasons last longer than a human life.

"For much of the planet's year the stars appear close together, giving it a familiar night-side and day-side," researcher Kevin Wagner says in a release. "As the planet orbits and the stars grow further apart each day, they reach a point where the setting of one coincides with the rising of the other—at which point the planet is in near-constant daytime for about one-quarter of its orbit, or roughly 140 Earth-years." The planet is four times the size of Jupiter, orbits a star 80% bigger than our sun, and is one of the youngest exoplanets found so far at roughly 16 million years old. And though researchers still have lots to learn about HD 131399Ab, "it shows there is more variety out there than many would have deemed possible," Wagner says. "What we do know is that planets in multi-star systems are much less explored, and potentially just as numerous as planets in single-star systems." (More space stories.)

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