Add Yahoo as a preferred source to see more of our stories on Google. Jupiter is already the biggest planet by far in our solar system, but new research suggests it was somehow once even larger than ...

An object eight times the mass of Jupiter may have swooped around the sun, coming superclose to Mars' present-day orbit before shoving four of the solar system's planets onto a different course. When ...

New research suggests the moons of Jupiter and Uranus may hint that our planetary neighborhood once had a third ice giant.

Our Solar System is plunging into chaos. Better hang on tight. The planets are getting knocked out of orbit. What could ...

Scientists have discovered a bizarre planetary system where a rocky world orbits farther out than giant gas planets, defying ...

An international team including astronomers from the Center for Astrophysics | Harvard & Smithsonian (CfA) has announced the discovery of a planet about twice the size of Earth orbiting its star ...

Seven planets are aligning in the night sky this week, creating a brief chance to see a "planetary parade." Worldwide, the best day to see the alignment is today, Feb. 28. Mercury, Venus, Mars, ...

Scientists may have discovered a dwarf planet far beyond Neptune — an unearthing that may disprove a longstanding theory about the possibility of a giant ninth planet. The dwarf planet's existence ...

The search for an unknown planet in our solar system has inspired astronomers for more than a century. Now, a recent study suggests a potential new candidate, which the paper’s authors have dubbed ...

Nearly all of the planets in the solar system are about to march through the night sky in a single-file line. This planetary alignment, sometimes called a planet parade, will include all of the solar ...