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A glint of sunlight reflecting from the surface of Saturn's moon Titan indicates the presence of a lake filled with liquid. Earlier observations showed features that look like terrestrial lakes and seas in Titan's northern polar region, but the presence of liquid had not been confirmed. Stephan et al. report the first detection of a directly visible glint, also called a specular reflection.

A specular reflection occurs when sunlight reflects off a smooth, mirror-like liquid surface. Cassini captured an image of the glint on 8 July 2009, and the researchers determined that it came from Kraken Mare, a large basin near Titan's north pole. Until recently the northern polar regions of Titan had been in winter darkness since Cassini's arrival in 2004; the recent direct illumination by sunlight made it possible to observe these optical reflections for the first time. Titan is the only body other than Earth in the solar system known to have stable liquid on its surface.