Add Yahoo as a preferred source to see more of our stories on Google. (Ianm35/iStock/Getty Images Plus) The Solar System is one of the comforting constants of human existence. No matter what else we ...

Two massive planets may have once existed in early solar system before being ejected, leaving behind evidence in unusual ...

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 ...

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 ...

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 ...

On a clear night, it dominates the sky, bright enough to cast shadows and large enough for dark patches and surface features to be seen without any equipment. It appears close, almost familiar. For ...

On August 24, 2006, our solar system lost a planet. It wasn't by cataclysmic destruction, but rather by the vote of the International Astronomical Union, which declared that Pluto, considered the ...

"It’s incredible to think there was once a world this large." The post Scientists Find Chunk of Lost Planet in Desert ...

Our solar system is a smashing success. A new study suggests that from its earliest period — even before the last of its nebular gas had been consumed — Earth’s solar system and its planets looked ...