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

An object eight times the mass of Jupiter may have swooped around the sun, coming superclose to Mars' present-day orbit ...

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

Stargazers will be treated to a rare seven-planet alignment in February. This is what scientists hope to learn.

Six planets are parading across the sky, appearing as some of the night's brightest stars. A few easy tips can help you ...

Six of our cosmic neighbors are expected to line up across the night sky tonight, in what has been dubbed a "planetary parade ...

Stargazers will be treated to a dazzling six-planet "alignment" this January.

Starting at 12:30 p.m. ET (1730 GMT) on Saturday (Jan. 25), astrophysicist Gianluca Masi of the Virtual Telescope Project ...

Narrator: Serious scientists, like myself, believe our solar system was formed by the collapse of a giant cloud of gas and rock and is held together by the gravitational pull of the Sun.