New Theory Says Planet 9 May Be a Captured Rogue Planet

Prior to becoming a political statement, the word “rogue” was used as far back as the 1830s as a way to describe a wild elephant (generally a male) that had become separated from its herd and as a result was “behaving in an erratic or dangerous fashion.” The same expression is now being used in a new theory that the still-unproven-yet-much-talked-about Planet 9 (or Nine or X) is a wild “rogue” planet, separated from its own solar system, that has joined up with ours and is possibly now or in the future behaving in an erratic and dangerous fashion. Should we start working on a giant elephant gun?

This “rogue planet” theory was presented at the recent meeting of the American Astronomical Society in Texas by astronomers James Vesper and Paul Mason from New Mexico State University. Rogue planets are known to exist and may outnumber standard orbiting planets in the Milky Way galaxy by at least 50 percent. When they get close to a new solar system, they can pass on by, enter a permanent or temporary orbit or just crash through, wreaking havoc and destroying everything in their path. One theory is that the behavior of a rogue planet depends on its size.

Vesper, a student and lead author of the study, and Mason, a math and physical science professor, modeled 156 different interactions between rogue planets of different sizes and our solar system. In about 60% of the simulations, the rogue was immediately flung back out into the galaxy to keep on roaming. In the next 30%, the rogue peacefully joined the solar system in what the researchers called a “soft capture.”

The last scenario, occurring in 10% of the simulations, showed the rogue planet performing a bocce ball move – banging into another planet and knocking it out of the solar system, thus turning it into a new rogue while taking its place. They called it the “kick and stay” maneuver and predicted it would require a massive planet and cause additional planetary collisions and asteroid-bouncing chaos in the solar system.

Fortunately, it doesn’t seem that kind of event has ever happened in our tightly-packed, orderly solar system, which means Planet 9 is probably about 10 times the size of Earth as many astronomers predict and is a “soft capture” rogue in a peaceful but long orbit around the Sun. If it ever gets close enough to study (which could happen next year, according to another Planet 9 “expert”), it could shed light on what planets from other solar systems look like and possibly tell us where it came from.

Or it could bocce ball us to Alpha Centauri.