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. Read more