Scientists have discovered a distant object at the edge of the solar system, which completes one orbit around the Sun every 40,000 years, a finding that supports the presence of Planet X. The newly found object, called 2015 TG387, was discovered about 80 astronomical units (AU) from the Sun. AU is a measurement defined as the distance between Earth and the Sun. For context, Pluto is around 34 AU, so 2015 TG387 is about two and a half times further away from the Sun than Pluto is right now.
Extremely distant solar system object discovered
The object is on a very elongated orbit and never comes closer to the Sun, a point called perihelion, than about 65 AU, according to researchers from the Carnegie Institution for Science in the US. Only 2012 VP113 and Sedna at 80 and 76 AU respectively have more-distant perihelia than 2015 TG387. Though 2015 TG387 has the third-most-distant perihelion, its orbital semi-major axis is larger than 2012 VP113 and Sedna's, meaning it travels much farther from the Sun than they do. At its furthest point, it reaches all the way out to about 2,300 AU. 2015 TG387 is one of the few known objects that never come close enough to the solar system's giant planets, like Neptune and Jupiter, to have significant gravitational interactions with them.
The discovery of 2012 VP113 led Sheppard and Trujillo to notice similarities of the orbits of several extremely distant solar system objects, and they proposed the presence of an unknown planet several times larger than Earth -- sometimes called Planet X or Planet 9 -- orbiting the Sun well beyond Pluto at hundreds of AUs.