Photos suggest recent water on Mars

Gullies like this could have been cut by waterNasa says it has found "compelling" evidence that liquid water flowed recently on the surface of Mars. The finding adds further weight to the idea that Mars might harbour the right conditions for life.

From CNN:
Two craters in the southern hemisphere that were originally photographed in 1999 and 2001 were examined again in 2004 and 2005, and the images yielded changes consistent with water flowing down the crater walls, according to the study.

Gullies like this could have been cut by waterScientists said five to 10 pools of water rushed down the craters in each case. In both craters, scientists found bright, light-colored deposits several hundred yards long in gullies that were not present in the original photos. They concluded that the deposits -- possibly mud, salt or frost -- were left there when water recently cascaded through.

Edgett said a combination of factors, including the shape and color of the deposits, led the team to believe it was recent water action and not dust that slipped down the slope. He said dust would leave dark deposits.

Water cannot remain a liquid on Mars for long because of subzero surface temperatures and low atmospheric pressure that would turn water into ice or gas. But scientists theorize that liquid water is being shot up to the surface from an underground source, like geysers.

Source: Images: NASA
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