Scientists still believed that liquid ethane and methane would be found near Titan's poles, where they expected to find lots of liquid. At Titan's south pole, a large dark area named Ontario Lacus was the first lake identified, possibly created by rain as clouds are often seen in the area. A possible shoreline was also identified at the pole in radar images. As the Huygens-Cassini probe flew by on July 22, 2006, its radar took pictures of the northern part of the planet (which was in its winter), a number of large, smooth areas were found on the surface near the northern pole. Based on this data, scientists announced "definitive evidence of lakes filled with methane on Saturn's moon Titan" in January 2007. The "Cassini–Huygens" team decided that the smooth areas are the hydrocarbon lakes they had been searching for, the first lakes found off Earth. Some valleys appear to have rivers.