Five years ago scientists proposed the hypothetical existence of a large world tens of millions of miles from the Sun, which has come to be known as "Planet Nine."
Scientists have previously predicted the existence of a large planet lurking in the farthest reaches of the Solar System. However, no observational evidence for this world has been found to date.
2015 TG387 has a weird elongated orbit and appears to be under the influence of a yet-to-be discovered planet.
Some researchers think that a hypothetical ninth planet exists in the furthest reaches of the Solar System.
The discovery of a small, icy world is raising questions about the entire prospect of a ninth planet.
The planet is believed to be 5,000 times the mass of Pluto.