As the United States prepares to celebrate its 250th anniversary, the history of the solar system tells its own story of ...

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

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 ...

A Jupiter-size exoplanet orbiting a dead star baffled astronomers. But the planet named WD 1856 b could preview the fate of ...

The rusty world is full of mysteries—and some of the solar system's most extreme geology. Learn more about Earth's smaller, colder neighbor.

So far, humanity has yet to find its first "exomoon"—a moon orbiting a planet outside of the solar system. But that hasn't been for lack of trying. According to a new paper by Thomas Winterhalder of ...

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 ...

Researchers have discovered a planet which, by all intents and purposes, should not be there. The world, coined WD 1856 b, is slightly larger than Jupiter and circles a dead star only about the size ...