Animation of a flight around Planet Nine. In a paper released on 20th January, 2016 in the Astronomical Journal, the possible existence of what has been called Planet Nine was theorised. The paper suggested that the known motions of some Kuiper Belt bodies could be explained by the presence of this theorised planet, which would orbit some twenty times further out than Neptune, and be approximately ten times the mass of the Earth. At two to four times the diameter of Earth, it is speculated to be an ejected ice giant, similar to Uranus and Neptune, with a shallow gas envelope. Its orbital period is reckoned to be between 10, 000 and 20, 000 years. In this depiction, the planet is imagined as having a thin rope-like ring system and a small moon.