Liquid water once shaped the Martian landscape dramatically, carving valleys, filling lakes, and forming vast oceans. Billions of years ago, during Mars' early days known as the Noachian and Hesperian ...

Add Yahoo as a preferred source to see more of our stories on Google. Ground-penetrating radar reveals a long-lost river system hidden under the surface of Mars. (NASA/JPL/UCLA/UiO/ETH Zurich) Far ...

For years, scientists have been intrigued by mysterious dark streaks running down the slopes of Martian cliffs and craters. These marks, called slope streaks and recurring slope lineae (RSLs), have ...

Hundreds of thousands of dark streaks are crawling down Martian hillsides, vanishing, and reappearing with the seasons. Two ...

"This experiment's never been run before on another world," said Amy Williams, an astrobiologist working on the Curiosity ...