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 ...

For the first time, scientists have created a detailed map showing huge, continent-sized river drainage systems on Mars. These ancient river networks date back billions of years, to a time when Mars ...

One of the great unsolved problems in modern planetary science is written on the surface of Mars. Mars has canyons that were carved by rivers, so it was once warm enough for liquid water. How—and ...

There might be a hidden ocean's worth of liquid water below the surface of Mars, seismic evidence suggests. According to a new paper published April 25 in the journal National Science Review, ...

Planetary scientists agree that Mars used to have liquid water on its surface and a water-rich atmosphere, far different from its current arid state. But an accounting of all the sources of water to ...