CAPE CANAVERAL, Fla. (AP) — Scientists say they finally have "solid evidence" for Planet X, a true ninth planet on the fringes of our solar system.

The gas giant is thought to be almost as big as Neptune and orbiting billions of miles beyond Neptune's path — distant enough to take 10,000 to 20,000 years to circle the sun. This Planet 9, as the two Caltech researchers call it, hasn't been spotted yet. They base their findings on mathematical and computer modeling, and anticipate its discovery via telescope within five years.

The two reported on their research Wednesday in the Astronomical Journal.

Once it's detected, the researchers insist there will be no Pluto-style planetary debate. They ought to know; one of them, Mike Brown, is the so-called Pluto killer.