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

The rover's 26th sample, known as "Silver Mountain," has textures "unlike anything we've seen before," NASA says.

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

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

Mars's moon Phobos is so strange that no one knows how it formed. But a forthcoming mission could solve this mystery - and a host of other puzzles connected to the solar system's deep past ...

Mars' southern hemisphere absorbs a lot of the sun's energy during the Red Planet's spring, and that may be causing Mars' ...

NASA has shared details of what to look out for in the night sky this month, with the moon appearing alongside a parade of planets.

A U.S. scientist searching for a civilization across 7 Earth clones circling the red dwarf star TRAPPIST-1 says its own alien ...

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

A new paper released today documents the first soil, airfall dust, and rock fragment samples collected by NASA for return ...

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