# Kindai University simulations point to an unseen planet of about 2 Earth masses in the outer Solar System

- Published: 2026-11-05 14:51 UTC
- Section: Sky & Space › Astronomy
- Tags: unknown planet outer Solar System, Kindai University, trans-Neptunian objects, Sedna orbit, planet of two Earth masses, Neptune migration, Vera C. Rubin Observatory
- URL: https://realtech.media/news/rt-5fba93df970f85fe75b01ec6_kindai_university_simulations/

**Orbits of small bodies beyond Neptune fit a model with a distant planet of 1–2 Earth masses; the planet itself has not been observed.**

![Kindai University simulations point to an unseen planet of about 2 Earth masses in the outer Solar System](https://sgzwpqqelzmajkcubgkl.supabase.co/storage/v1/object/public/rt-media/2026/11/ef9bc985bb399a1d.jpg)
*CactiStaccingCrane, Wikimedia Commons, CC BY-SA 4.0*

A research team at Kindai University and other institutions reports that an unknown planet about twice the mass of Earth may exist in the outer Solar System, newssalt.com writes. [1] The study was published on October 28 in Monthly Notices of the Royal Astronomical Society. [1]

Some small bodies beyond Neptune stay far from its orbit even at closest approach to the Sun, have orbits inclined 45 degrees or more, or move on extremely elongated paths. Sedna stays about 76 astronomical units away at closest approach. [1]

The team simulated the motion of bodies since the Solar System formed, including Neptune's migration. Protoplanets of Mars to Earth mass were ejected and did not reproduce the observed distribution, while a distant planet of 1–2 Earth masses did. A planet of about twice Earth's mass, with a semi-major axis of 350–500 astronomical units and perihelion near 200 astronomical units, also explained Sedna-like orbits. [1]

This is a simulation result: the planet has not been found. Vera C. Rubin Observatory observations may test it. [1]

## Sources

1. [newssalt.com](https://www.newssalt.com/40717)

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Source: RealTech, realtech.media — https://realtech.media/news/rt-5fba93df970f85fe75b01ec6_kindai_university_simulations/