Mars is a cold, dry, desert-like planet. But billions of years ago, scientific evidence suggests that it had a thick atmosphere, which kept it warm enough to support flowing water on its surface. So, ...

Ancient shoreline features hint that water on Mars once formed a vast ocean.

Mars keeps refusing to behave like the dead, simple world many scientists once imagined. Each new rover trench, fractured boulder and orbital scan is turning up stranger chemistry, unexpected ...

Using images from cameras on Mars orbiters, an international research team has discovered structures on Mars that are very similar to classic river deltas on Earth. These are traces of rivers that ...

The findings potentially solve the paradox of how liquid water seems to have persisted on Mars even when the climate grew too cold.

"Mars and its secrets have fascinated and mystified humans since ancient times. Its vivid color and visibility to the naked eye, its geologic kinship with Earth, its potential as our best hope for ...