Overview
- A team led by Princeton astrophysicist Amir Siraj analyzed 154 Kuiper Belt objects and found systematic orbital tilts beyond about 80 AU that known planets do not explain.
- Computer simulations reproduce the pattern if a slightly inclined planet orbits at roughly 100–200 astronomical units from the Sun.
- Press accounts describe the candidate’s mass between Mercury and Earth or between Mars and Earth, reflecting uncertainty in the estimate.
- The hypothesized body, informally dubbed Planet Y, is presented as distinct from prior Planet Nine proposals affecting a different region.
- The object has not been directly observed, and researchers point to the Vera C. Rubin Observatory’s wide-field surveys as the most likely route to confirmation or refutation.