For decades, 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 say they have found 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.
The best explanation they have so far is that those dark finger-like streaks are a kind of salty water that is running on or just below the Martian surface. At one location - Newton Crater - they have counted as many as 1000 of these possible streams flowing down the slopes and into a basin.