Rain on Mars (Credit: NASA

Images of layered sedimentary deposits and deltas on Mars have provided evidence for lakes and flowing rivers that carried eroded material downstream. A team of researchers also believes there is evidence for precipitation in the Red Planet’s past. “For years scientists have been suspecting that the current appearance of the landscape has, in part, been shaped by rivers that cut into the surface,” said Ernst Hauber of the German Aerospace Center. “We can see layered sediments where these valleys open into impact craters. The shape of certain sediments is typical for deltas formed in standing water.” Hauber and his team also believe that surface runoff from rain or snowmelt completes the picture of past water on Mars.

There seems to be more and more evidense coming from NASA’s HiRISE that Mars was once very similar to Earth, in both it’s surface and it’s atmosphere. At some point however Mars has taken a very different tack and ended up as very cold, very dry and very barren. Other recent photographs from Mars show dried up lakes, river valleys, estuarys and other features associated with a once wet planet.

Whatever did happen was very brief in Mar’s overall history and any precipitation that did occur dried up around 3.5 to 3.8 billion years ago.

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