The number of planets that orbit the sun depends on what you mean by “planet,” and that’s not so easy to define ...

An object eight times the mass of Jupiter ... day orbit before shoving four of the solar system's planets onto a different course. A planet-size object that possibly once visited the solar system ...

Based on new simulations, scientists believe that giant gas planets across the ... "small" that means "closer to the size of Jupiter, which is still a giant planet" — could help Dong and her ...

Stargazers who have heard of an amazing planetary alignment coming later in January may be in for a letdown if they look up at the night sky expecting to be dazzled. Yes, six planets will be ...