Mars

A low-density, weak-gravity region has been found below Olympus Mons and the Tharsis volcanoes, while Mars' northern hemisphere is littered with puzzling high-gravity structures beneath the surface.

Scientists at NASA's Jet Propulsion Laboratory have recreated spider-like araneiform terrain, a geologic formation found on Mars, in a lab on Earth.

The most comprehensive map of clouds on Mars includes a variety of cloud patterns, including some that are unlike anything seen on Earth.

NASA's Curiosity rover has captured a spectacular sight from the surface of Mars: The first-ever photo of Earth alongside the Red Planet's moon Phobos.

Newly released images of Mars reveal a "smiley" salt deposit on the Red Planet's surface. A related study suggests that similar deposits, which were left behind from ancient lakes, may be a good place to look for signs of former life on Mars.

The cause of mysterious methane spikes on Mars may be a strange form of alien life — or it may just be interesting chemistry. Either way, something odd is happening on the Red Planet.

A long-lost moon could explain why Mars is so different from the other rocky planets in the solar system.

NASA's MAVEN mission and the Hubble Space Telescope have teamed up to reveal new insights into how Mars' water is leaking into space.

As space agencies and private companies look toward sending human crews to Mars, they'll have to find ways to mitigate the dangers posed by high-energy radiation from solar storms.

Astronomers have traced the origins of 200 meteorites to five impact craters in two volcanic regions on Mars, known as Tharsis and Elysium.