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

But of these planets, which is nearest to the sun? Mercury is the closest planet to the sun, followed by Venus, Earth, Mars, ...

When you first learned about the Solar System, you probably saw diagrams that made it look orderly, with planets arranged in ...

The eight planets in our solar system orbit the sun in roughly the same plane, because they all originally formed from the ...

Ever since Isaac Newton famously talked about gravity, its dominance as a force in our solar system has been well known. It's ...

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

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

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

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.

A new study claims it is possible an "alien visitor" could have warped our solar system during its earliest years.