Researchers at the California Institute of Technology have found evidence in the outer solar system of an object that could be a real planet.

“This is the first serious claim for the existence of an additional planet in the solar system,” said planetary scientist Alessandro Morbidelli of France’s Observatory of the Cote d’Azur.

Nicknamed Planet Nine, it “has a mass about 10 times that of Earth and orbits about 20 times farther from the sun” than Neptune. That means “it would take this new planet between 10,000 and 20,000 years to make just one full orbit around the sun,” according to Caltech


“The existence of another planet has been spoken about 100 times before,” Brown says. “But this is the first time in 150 years that we can say we have convincing evidence that the census of the solar system is incomplete

Other researchers say the existence of so-called “Planet Nine,” while plausible, still needs to be confirmed. But experts also say the study laying out the case contains the most convincing evidence yet that a giant planet hovers much farther away than ever imagined.

Already, Caltech is pretty confident Planet Nine is large enough to rule out any debate about whether it’s a true planet.