Tropical' lake possible on Saturn moon

A long-lasting "tropical" lake of liquid methane on Saturn's moon Titan may be replenished by underground wells of hydrocarbons, U.S. astronomers report. While the Cassini spacecraft confirmed the presence of such lakes in Titan's polar regions in 2004, it had been unknown whether similar bodies could survive in the moon's marginally warmer lower latitudes -- its "tropics" -- without evaporating, they said. Researchers at the University of Arizona in Tucson analyzed Cassini data on sunlight reflected from Titan's tropical regions and found a highly reflective oval-shaped black feature almost a thousand square miles in area, NewScientist.com reported Wednesday. Its shape and color is consistent with a liquid methane lake, they said. If it is in fact a lake, it is long-lived, having persisted since at least 2004 through both rainy and dry seasons, suggesting it's unlikely to be just a big rain puddle but rather could be fed by hydrocarbon wells, the researchers said.