A hypothesised planet of five to ten Earth masses at hundreds of astronomical units, proposed by Konstantin Batygin and Michael E. Brown in the Astronomical Journal in January 2016 to account for the clustered orbits of distant Kuiper belt objects. Its period runs to many thousands of years and it never enters the inner solar system, which is the whole of the difference from Nibiru, with which it is routinely conflated online. It remains unconfirmed. Phan and colleagues, in Publications of the Astronomical Society of Australia in 2025, cross-matched the IRAS far-infrared survey of 1983 against AKARI’s of 2006, found thirteen candidate pairs and one that survived image inspection at 500 to 700 astronomical units and seven to seventeen Earth masses, and proposed Dark Energy Camera follow-up. The authors note that two detections cannot fix a Keplerian orbit, and Brown has observed that if the candidate is real its orbit is inconsistent with the clustering Planet Nine was proposed to explain. The Vera Rubin Observatory survey is the expected decider. The entry is kept here because it is the falsifiable neighbour of an unfalsifiable claim, and because the same 1983 dataset turns up on both sides of that comparison.
Connections
Nibiru · Zecharia Sitchin · Ancient Astronaut Hypothesis · Cydonia · The Wars of Gods and Men