A giant, unknown planet might exist in our outer solar system

Astronomers at the California Institute of Technology announced on Wednesday they’d found evidence for a massive, faraway planet. If true, it would constitute the ninth planet in our solar system, an honor once bestowed on Pluto, which has since been demoted to dwarf-planet status. They’ve nicknamed the new object Planet Nine.

Planet Nine’s mass is believed to be about 10 times that of Earth, and it’s distance, 20 times farther away from the sun than Pluto. To put that in perspective, scientists say it would take Planet Nine between 10,000 and 20,000 years to make one full orbit around the sun, according to a press release on the finding. The paper was published on Wednesday in The Astronomical Journal.

READ MORE: How ‘killing’ Pluto redefined the solar system

As imagined, Planet Nine is so far away and reflects so little light that it’s difficult to see through even the most powerful telescopes. Evidence of its existence comes instead from dwarf planets and other icy objects around it, which, writes the Washington Post, “appear to be influenced by the gravity of a hidden planet .. a ‘massive perturber.’ The astronomers suggest it might have been flung into deep space long ago by the gravitational force of Jupiter or Saturn.”

The region that it gravitationally dominates, according to the Cal Tech release and researcher Mike Brown, “makes it ‘the most planet-y of the planets in the whole solar system.'”

Today’s announcement comes after an international team of researchers in 2014 announced that 13 of the objects in the Kuiper belt shared strange orbital patterns that could be explain by an unknown object — a planet.

“Although we were initially quite skeptical that this planet could exist, as we continued to investigate its orbit and what it would mean for the outer solar system, we become increasingly convinced that it is out there,” says Konstantin Batygin, an assistant professor of planetary science and one of the study authors, according to the CalTech release. “For the first time in over 150 years, there is solid evidence that the solar system’s planetary census is incomplete.”

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