Back to today’s briefing

Story perspectives

Astronomers Pursue Mysterious "Planet Nine" Beyond Neptune

6/21/2025

46 3

Summary

Story summary

Astronomers are on the hunt for a mysterious ninth planet, known as "Planet Nine," which could be 5-10 times the mass of Earth and lurks in the distant reaches beyond Neptune. Recent studies reveal that chaotic early planetary systems might have captured such giants, raising hopes of finding Planet Nine using cutting-edge heat signature detection techniques.

1 of 1

Story summary

Astronomers are on the hunt for a mysterious ninth planet, known as "Planet Nine," which could be 5-10 times the mass of Earth and lurks in the distant reaches beyond Neptune. Recent studies reveal that chaotic early planetary systems might have captured such giants, raising hopes of finding Planet Nine using cutting-edge heat signature detection techniques.