More glints of sunlight from liquid lakes on Saturn’s moon Titan

Astronomers have confirmed sunlight glinting from liquid lakes on the surface of Saturn’s moon.

Liquid lakes on Saturn’s large moon Titan are becoming more and more real in astronomers’ eyes and apertures (holes in optical equipment through which light travels).

Since July of 2006, astronomers scrutinizing images from the Cassini spacecraft have contemplated possible lakes on Titan. By early January 2007, astronomers were even more confident. There appear to be not just lakebeds, but actual lakes containing liquid on Saturn’s moon. In December of 2009, Cassini seemed to detect a glint of sunlight, from a Titan lake. Now more astronomers have confirmed sunlight glinting from liquid lakes on the surface of Saturn’s moon.

Earlier observations showed features that look like terrestrial lakes and seas in Titan’s northern polar region, but the presence of liquid was not confirmed. Stephan Katrin of the Institute of Planetary Research and others report the first detection of a directly visible glint – also called a specular reflection – which 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, lake-shaped 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 largest moon of the planet Saturn.

Images from the Cassini spacecraft – which has been in orbit around Saturn since 2004 – indicate that some 75 lakes lie near Titan’s north pole. The lakes range in size from 3 to 60 kilometers – about 2 to 40 miles.

By the way, Titan’s lakes don’t have liquid water. They can’t because Titan is so far from the sun that any water on its surface would be solid ice. Instead of having liquid water, Titan’s lakes are thought to be filled with methane in a liquid form.

But because Titan is so cold, its methane can also become liquid and even solid. It probably rains and snows methane on Titan, just as it rains and snows water here on Earth. So, that means Titan – Saturn’s moon – is the only world we know besides Earth to have liquid lakes.

Deborah Byrd