space

Why This Scientist Says There's a ‘Planet 9' – Even Though He Hasn't Seen It

Michael Brown, best known as the Caltech scientist who “demoted” or “killed” Pluto, believes there is a ninth planet in the far reaches of the solar system that has not been discovered yet. The man whose team previously discovered dwarf planets Eris and Sedna explains his hunch about the next planet out there.