/learn/publications/b/blog/posts/nasa-says-liquid-flowing-water-exists-today-on-marsDark, narrow streaks on Martian slopes such as these at Hale Crater are believed to be formed by seasonal flow of water. The streaks are roughly the length of a football field. Photo courtesy of: NASA/JPL-Caltech/Univ. of Arizona.Scientists rep...en-USTelligent Community 12