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 – ...

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.

HELENA — The planets are aligned. Six planets, Mars, Jupiter, Uranus, Neptune, Venus and Saturn can be seen in the night sky.

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

To better understand why the planets have variable compositions ... to the formation of the gas and ice giants in the outer solar system. This first-order model of planetary growth in the solar ...

All of our solar system’s planets are lining up to parade through the night sky at once. This extraordinary celestial event will see the sky scattered with seven visible planets in what is known ...