A type of natural gas in Titan's poles in Saturn

Scientists had already spotted lakes of methane, a type of natural gas in Titan's poles, but so far none had been found in its equatorial regions, which are mostly arid and vast expanses of dunes.

"It was totally unexpected, because the lakes are not stable in tropical latitudes," said Caitlin Griffith of the University of Arizona, director of the team responsible for the finding.

Thanks to the images provided by the Cassini spacecraft orbiting Saturn since 2004, the team was able to detect a black mark of 2,400 square kilometers, consisting of small dark ovals, which constitute a set of small lakes and swamps, scattered throughout the tropical surface of Titan. They said further analysis of the dark spot suggest the presence a hydrocarbon lake about 2,400 square kilometers. Also found evidence of four tropical lagoons near the lake.

Although in 2011 the camera sensitive to infrared allowed Cassini incorporates signs of methane rain on the dunes near the Ecuador of Titan, scientists do not believe that the origin of the lakes is this. Griffith and his colleagues believe that Titan's tropical lakes were formed by the existence of large underground reservoirs of liquid methane during the last 10,000 years would have expelled this material to the surface.