Two astronomers in Japan have recently uncovered possible evidence pointing to the existence of an Earth-like planet, referred to as “Planet Nine,” in the outer solar system behind Neptune.
“We predict the existence of an Earth-like planet and several TNOs [trans-Neptunian objects] on peculiar orbits in the outer solar system, which can serve as observationally testable signatures of the putative planet’s perturbations,” the scientists said.
The scientists projected that Planet Nine would have a mass between 1.5 and 3 times that of Earth, located at 500 astronomical units (AU) from the Sun, with an orbit inclination of 30 degrees, if it indeed existed.
They believe that the discovery of such a planet can help unravel fundamental properties of the Kuiper Belt, including “a prominent population of trans-Neptunian objects with orbits beyond Neptune’s gravitational influence, a significant population of high-inclination objects, and the existence of some extreme objects with peculiar orbits.”
“It is plausible that a primordial planetary body could survive in the distant Kuiper Belt as a KBP [Kuiper Belt planet], as many such bodies existed in the early solar system,” the researchers wrote in the study.
“More detailed knowledge of the orbital structure in the distant Kuiper Belt can reveal or rule out the existence of any hypothetical planet in the outer solar system,” they added.
“The existence of a Kuiper belt planet may also offer new constraints on planet formation and dynamical evolution in the trans-Jovian region.”
‘Bizarre, Highly Elongated Orbit’
In 2016, Caltech researchers found evidence of a planet “tracing a bizarre, highly elongated orbit” in the outer solar system, which has a mass about 10 times that of Earth and orbits about 20 times farther from the Sun on average than Neptune does.
The researchers, Konstantin Batygin and Mike Brown, estimated that this new planet would take between 10,000 and 20,000 years to make just one full orbit around the sun.
The planet has not been observed directly. The researchers discovered the planet’s existence through mathematical modeling and computer simulations.
“There have only been two true planets discovered since ancient times, and this would be a third. It’s a pretty substantial chunk of our solar system that’s still out there to be found, which is pretty exciting.”