Ninth Planet in Solar System

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Credits: R. Hurt / Infrared Processing and Analysis Center / Courtesy of California Institute of Technology / AP

 
A planet larger than Earth could be hiding in the cold, dark depths of the solar system. The presence of the planet, which would lie far beyond Pluto, is betrayed by the curious orbits of a handful of distant icy worlds.

As described Wednesday in the Astronomical Journal, the gravitational signature of a large, lurking planet is written into the peculiar orbits of these farflung worlds. Called extreme Kuiper Belt Objects, the misbehaving bodies trace odd circles around the sun that have puzzled scientists for years.

It’s tantalizing evidence that a ninth large planet might live in the solar system, though the world hasn’t been detected yet.

“If there’s going to be another planet in the solar system, I think this is it,” says Greg Laughlin of the University of California, Santa Cruz. “It would be quite extraordinary if we had one. Fingers crossed. It would be amazing.”

The team calculated that the planet, if it’s there, would be about 10 times as massive as Earth, or roughly three times larger. That makes it a super-Earth or mini-Neptune—a type of planet the galaxy is incredibly efficient at assembling, but which has been conspicuously absent from our own neighborhood.

And it’s really far away. Simulations suggest that the planet’s closest approach to the sun would be roughly 200 to 300 times farther out than Earth’s. Its most distant point? That’s way out in the hinterlands, between 600 and 1,200 times farther than Earth.

“This thing is on an exceptionally frigid, long-period orbit, and probably takes on the order of 20,000 years to make one full revolution around the sun,” says Caltech’s Konstantin Batygin, who is one half of the planet-sleuthing team.

 

 

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