Ancient Oceans on Mars
It is now widely accepted that Mars was once a very wet place. About four billion years ago Mars would have had enough water to cover its entire surface in a liquid layer about 140 metres deep. It is likely that the liquid would have pooled to form an ocean occupying almost half of Mars’s northern hemisphere, and in some regions reaching depths greater than 1.6 kilometres. This artist’s impression shows what the planet may have looked like with its ancient ocean. Imagine: could life have lived in such a place?
Credit: ESO/M. Kornmesser