An artist’s conception of Planet 9, or Planet X, which scientists theorize orbits in the distant solar system.  (Robin Dienel/ Carnegie Institution of Washington)

The race is on to find the giant planet that several teams of astronomers are convinced orbits far out beyond Pluto, but is nonetheless still part of our solar system.  Proving the existence of what has become known as Planet X, or Planet 9, would be a discovery for the textbooks and would inevitably change our understanding of how our solar system was formed.

The technology and luck needed to image the planet (if it truly is there) has thus far fallen short, but the discovery of another set of distant solar system objects traveling in surprising orbits has added to the indirect findings that point to a substantial, and perhaps giant planet in the general vicinity.

The new findings come from Scott Sheppard of the Carnegie Institution for Science and Chadwick Trujillo of Northern Arizona University, who two years ago provided some of the first intriguing inklings that this distant planet might exist in our solar system.  That information was subsequently modified and broadened by a California Institute of Technology team, but with the same conclusion that a substantial Planet 9 appeared to be present in the outer solar system.

“What we’ve just released is data on the first extreme objects since the {2014 and 2016} reports of a theorized Planet 9,  and they show the same clustering and orbiting patterns that we think are likely caused by a major planet,” Sheppard said.

“This continues the trend of finding these objects — small dwarf planets or maybe icy objects — that were pushed into similar orbits in ways we think only planets can do.”

“We need more,” he said, “but the evidence is mounting, and at this point I’d say there’s an 80 percent likelihood that the planet is there.”

An illustration of the orbits of newly-discovered small, trans-Neptune objects 2013 FT28, 2014 SR349, and previously known extremely distant Solar System objects. The clustering of most of their orbits indicates that they are likely be influenced by something massive and very distant, the proposed Planet 9 . (Carnegie Institution of Washington, Robin Dienel)

Some call the potential celestial object Planet X and some call it Planet 9 — as in, the ninth planet in our solar system now that Pluto has been demoted to a dwarf planet. … Read more