The number of planets that orbit the sun depends on what you mean by “planet,” and that’s not so easy to define ...

All seven of the other planets in our solar system are about to become visible at once in a great planetary alignment – ...

Beyond Neptune lies the Kuiper Belt, a vast expanse of icy bodies that may hold clues to the solar system’s formation. These ...

"Our Sun (Sol) is marked by a black hexagon, and its orbital path is indicated by a grey solid line (top row only). Alpha Centauri's location and path are shown by a yellow star and a solid blue line ...

However, this year a powerful new telescope is coming online that could prove once and for all that there really is a ninth planet in our Solar System. The same year that Pluto was ignominiously ...

Plate tectonics give Earth its mountains, earthquakes, continental drift and maybe even helped give rise to life itself. But do other planets in the solar system have them too?

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.

On Feb. 24, from west to east, you can see Mercury, Saturn, Neptune, Venus, Uranus, Jupiter and Mars, all spanning 117.5°, ...