There have been questions about a mysterious ninth planet in our solar system for nearly a decade. Pluto was unseated as number nine in 2006. Now, a group of international researchers say they may ...

The Ghost of the Solar System: Why Can't We Find Planet 9? Deep in the outer reaches of our solar system, far beyond Neptune ...

A recent research paper suggests that a planet may exist far beyond Neptune — less than 20 years after the previous ninth planet, Pluto, was demoted. That research paper, accepted last month for ...

When the object now known as 1I/ʻOumuamua streaked through the inner Solar System in 2017, it instantly rewrote the playbook ...

Scientists may have discovered a dwarf planet far beyond Neptune — an unearthing that may disprove a longstanding theory about the possibility of a giant ninth planet. The dwarf planet's existence ...

A rare discovery beyond Neptune is forcing scientists to rethink early solar system dynamics and the forces that shaped ...

After studying thousands of computer simulations of the solar system, researchers at Rice University and the Planetary Science Institute think there’s a 40% chance an elusive “Planet Nine” or “Planet ...

Earth has a newly-discovered neighbor in the solar system. But the heavenly body – possibly a dwarf planet à la Pluto – isn't a frequent visitor. Located beyond Neptune, its extreme orbit ...

Pluto, once considered the ninth planet, was reclassified as a dwarf planet in 2006 because it shares its orbital path with ...