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 ...

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

Planetary alignments aren't rare, but they can be when they involve six of the eight planets in our solar system.

creating an uncommon seven-planet alignment, which will not be seen again until 2040. The eight major planets in our Solar System orbit the sun on the same flat plane but at vastly different speeds.

Though the planets are always “aligned,” seeing more than four in the sky is more uncommon. February’s lineup is a chance to ...

When astronomers found a large world farther out than Pluto, it became one of the final nails in the coffin of our ninth ...

Known as the "Parade of Planets," the celestial event will feature appearances from Mars, Jupiter, Uranus, Venus, Neptune and ...

Mars, Venus, Jupiter and Saturn should be visible to the naked eye, but get a telescope and you can spot Neptune and Uranus.

Heads up! Four planets are visible in the evening sky this month, and another two planets can be found with a little help.