Yesterday, images of the Saturnian moon Titan taken by the Cassini orbiter revealed what may be a sea or ocean on the surface.  Not of water of course...

It's far too cold on Titan for there to be liquid water on the surface, but a sea of liquid methane is definitely a possibility.  Scientists are not jumping to any conclusions, saying only that there is a region of dark terrain on one side of what appears to be a continent, with a boundary "that resembles a terrestrial shoreline".  If indeed this is a sea of some sort, it would be big news.  I think to date, we've never imaged any sort of fluid on the surface of another world, unless you count lava on the Jovian satellite Io.

(false color image)

The bright colored region below and to the right of the dark region is thought to be a continent, which is informally being referred to as "Xanadu".  Olivia Newton John fans would probably be delighted.

The idea of any sort of ocean on Titan is very important to me in a rather personal way.  Once, when in college and listening to Van Morrison performing "An Evening Meditation", I had a daydream about walking with my future wife on a beach under the golden sky of Titan, with the distant sun reflecting off the strange glittering waves and huge plateaus of ice in the distance.  Since then I have always seen that breathtaking landscape in my mind whenever I think of Titan.

The scientists who are planning to drop the Huygens probe into Titan's atmosphere in January are also interested in the possibility of oceans on the moon's surface.  The Huygens probe is designed to float in fluid.  Discovery of a large body of liquid would be a boon to the team which has selected a landing site on the surface.  Apparently a fluid landing is preferred. The Huygens probe is more of an atmospheric probe than a surface probe, and therefore isn't designed to "touch down gently".  However the probe is expected to have 30 minutes of battery life upon reaching the surface, so if it does not crash, there is a chance that some science can be done before it goes offline.

Higher resolution images taken today reveal an even more tantalizing view of this region.  Streaks detected in the moon's surface material are described as possibly:

...caused by the movement of a fluid over the surface, such as wind, hydrocarbon liquids, or a migrating ice sheet, such as a glacier. The large-scale streaks are most easily explained by winds in Titan's massive atmosphere...

Up until recently, details of Titan's surface have been a mystery because the moon is shrouded in a thick yellow-brown haze.  No other moon in the solar system has such a thick atmosphere and in fact, most moons have no atmosphere at all.  Apparently, certain wavelengths of infrared light can pierce Titan's haze and reveal the surface, and Cassini is equipped with cameras capable of doing so.

Check out the Cassini Imaging Team's page covering the first closeups of Titan's surface for some truly breathtaking images.