Scientists Find Evidence For A Giant 9th Planet Lurking In The Solar System

January 21, 2016

Caltech researchers have found evidence of a giant planet tracing a bizarre, highly elongated orbit in the outer solar system.

The object, which the researchers have nicknamed Planet Nine, has a mass about 10 times that of Earth and orbits about 20 times farther from the sun on average than does Neptune (which orbits the sun at an average distance of 2.8 billion miles). In fact, it would take this new planet between 10,000 and 20,000 years to make just one full orbit around the sun.

"There have only been two true planets discovered since ancient times, and this would be a third," says Mike Brown, the Richard and Barbara Rosenberg Professor of Planetary Astronomy. It's a pretty substantial chunk of our solar system that's still out there to be found, which is pretty exciting."

Artistic rendering / Credit: Caltech/R. Hurt (IPAC)

If this ninth large planet is out there, it's so distant and so dim that it isn't surprising the world hasn’t been detected yet. "This thing will be faint. Like, crazy faint," says Greg Laughlin of the University of California, Santa Cruz, who calculated that Pluto could be as much as 10,000 times brighter than the new planet. At such extreme distances, even a relatively large planet wouldn't have a heat signature detectable by current surveys, and it wouldn't reflect much sunlight. That means astronomers searching for it not only need to use incredibly powerful telescopes, they need to know where to look.

In other words, it's like looking for a single, moving speck of light in a vast and nearly impenetrable sea of stars.