NASA says that at least one of the large lakes on Titan, a moon of Saturn, consists of liquid hydrocarbons. The hydrocarbon ethane has been positively spotted, making Titan the only other object besides Earth known to hold liquid on its surface.

Thanks to the Cassini mission and the data provided by numerous flybys of Titan, analysis of light absorption and reflectivity in infrared light helped confirm the existence of the liquid lake. Scientists have seen hundreds of dark, lake-like features on Titan but did not know whether these features were liquid or merely dark rock or other dark material.

The hydrocarbon lake is called Ontario Lacus in the south polar region of Titan, and slightly largely that Lake Ontario between Canada and the United States. Titan’s surface temperatures approximate 300 degrees Fahrenheit below zero, yet shows evidence of evaporation, rain and fluid eroded and fluid carved channels draining into the hydrocarbon lake bed.

Earth has a hydrological cycle based on water but Titan has a cycle based on methane. Scientists have ruled out the presence of water ice, ammonia, ammonia hydrate and carbon dioxide in Ontario Lacus while observations also suggest the lake is evaporating as mentioned above. The lake is ringed by a dark beach. A black lake merges with the bright shoreline. Cassini observed a shelf and beach being exposed as the liquid in the lake evaporates.

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