A New Giant Planet In Our Solar System? Evidence Mounts | Video

Neptune’s existence was proposed before it was detected, based on how its mass affected the motion of Uranus. Now, a proposed planet – smaller than Neptune but larger than Earth – has been proposed to explain the configuration of Pluto-sized Kuiper Belt Objects. (Full Story)

Infographic: 'Planet Nine': Facts About the Mysterious Solar System World

Gallery: The Evidence for 'Planet Nine' in Our Solar System

credit : Science/AAAS