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 – ...

The enormous visitor to our solar system may have been about 8 times the mass of Jupiter, and come nearly as close to the sun ...

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

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

Baker said that there are other astronomical events that may be more interesting than the parade of planets. Baker said Mars ...