Scientists have found evidence of flowing water on Mars.
The Nasa space agency found frozen water on the planet 10 years ago, but this is the first time that they have discovered evidence of liquid water.
New images in the summer months highlight dark, finger-like formations that run down the red planet's slopes.
In winter, these lines fade away.
"The best explanation for these observations so far is the flow of briny water," said Alfred McEwen of the University of Arizona.
Following the discovery, NASA has said that the presence of the water could indicate that there is life on Mars.
NASA Administrator Charles Bolden said: "NASA's Mars Exploration Program keeps bringing us closer to determining whether the Red Planet could harbor life in some form… and it reaffirms Mars as an important future destination for human exploration."
Nasa is currently building a spacecraft to take humans to Mars by 2030.
