Shifting dark streaks on Mars' surface imply that there is water flowing on the Red Planet. The discovery was announced Thursday at a NASA news conference in Washington. 

Lead author of the Science journal study, Alfred McEwen, made these observations using the HiRISE camera aboard NASA's Mars Reconnaissance Orbiter, which saw features on some of the planet's slopes that seemingly fade in the winter and reappear during springtime. 

The possible liquid (one of the four states of) water confirms speculation that Mars houses microbial organisms. The prerequisites for life are liquid water plus carbon-based molecules plus a source for energy.   

The liquid water flows occur near Mars' equator in the southern hemisphere, where temperatures are appropriate for water. The findings have discarded the theory that water only exists in the form of ice in the polar regions of Mars.

The liquid water is thought to be salty because a previous study found that Mars' surface is salty. The flows have been described as small and unlike those on Earth. The flows are also very narrow, 0.5 to 5 yards wide. 

Seven of these sites have been confirmed and 20 to 30 are possible, scientists said.