Our solar system is a smashing success. A new study suggests that from its earliest period—even before the last of its ...

Is there a massive undiscovered planet on the outer reaches of the solar system? The idea has been around since before the discovery of Pluto in the 1930s. Labeled as planet X, prominent astronomers ...

With a diameter of 88,846 miles at its equator, Jupiter is the biggest planet in our solar system. It’s eleven times larger than Earth, so big in fact that its gravitational forces are thought to be ...