At the center is the sun, a yellow dwarf star that contains 99.8% of the solar system's mass. Everything else — from the eight major planets to dwarf planets, comets, asteroids, and icy objects ...

Our solar system may have a ninth planet after all, following the declassification of Pluto nearly two decades ago, ...

Astronomers have detected a promising sign of a ninth planet lurking at the the farthest reaches of the Solar System.