Planet Nine

Astronomers hypothesize that a massive planet orbits our sun, unseen.

Planet Nine: Researchers Find Evidence of a Giant Planet Beyond Pluto

This artist's conception illustrates a Jupiter-like planet alone in the dark of space, floating freely without a parent star.

Its orbit is so large it would take nearly 20,000 years to go around the sun once.

Massive Shadowy Planet May Lurk Beyond Pluto

Artist's impression of Sedna, dwarf planet in the Kuiper Belt

A curious orbital pattern among objects in the Kuiper Belt points to the presence of a hidden planet at the very edge of the solar system, too far for us to detect but large enough to exert strong gravitational effects on surrounding celestial...