Biggest planet: Learn how big each planet

Learn how big each planet is compared to Earth and how far they orbit from the Sun. Jupiter is the largest planet, about 11 times wider than Earth, and Mercury is the smallest, about one-third the width of Earth. Prior to 1992, when the first exoplanet was discovered, the gas giant Jupiter, which is about 11 times as wide as Earth, held the title of the biggest known planet. But Jupiter is a pip-squeak... How much bigger? What is the biggest planet we know of? The answer depends on several factors, including how you define a planet. Even so, there are a few candidates for the largest known planet. Jupiter is the fifth planet from the Sun, and the largest in the solar system – more than twice as massive as the other planets combined.