Water on Mars: Scientists find strongest evidence yet

Space scientists have searched Mars for signs of water, the liquid generally believed to be essential for life. Now, they may well have found it.

Scientists announced Thursday that they had detected dozens of slopes across the southern hemisphere of the planet where previously undetected dark streaks come and go with the seasons. When the planet heats up, the streaks appear and expand downhill. When it gets cold, the streaks disappear.