Mars may have been a "blue planet" with an ocean the size of today's Arctic Ocean, a new study suggests.

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 ...

Mars, now a dusty world of rusted rock and thin air, once carried enough water to transform its face into something far more ...

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

Long before Mars turned into the frozen desert you see today, water shaped its surface in dramatic ways. Rivers cut through highlands, lakes pooled inside craters, and floods tore open canyon walls.

New research suggests Mars was once a blue planet, as scientists identify river deltas and signs of a vast ancient ocean on ...

Three billion years ago, you could have stood on Mars and watched a river spill into a sea. That picture is still speculative ...

Mars is absolutely dripping with evidence that the red planet was once a striking blue, complete with glistening lakes, ...

Scientists have traced ancient Martian shorelines inside a giant canyon, revealing where a vast ocean once stood and why ...

Billions of years ago, it rained on Mars. The water collected in valleys and rivers, filled and spilled over the rims of craters, and was funneled into canyons, perhaps even making its way to a large ...