A bright river on Xanadu’s southwest: In this Cassini RADAR view captured on May 28, 2008, an unusually bright river valley exits the Xanadu region to the north. Credit: NASA / JPL
The Planetary Society blog reports that the NASA Cassini RADAR team has spotted some river channels on Titan that shine so brightly in radar images, there must be something special going on to explain that brightness.
What we’re seeing is the same phenomenon that makes reflective paint on street signs shine brightly in headlights. But instead of tiny plastic beads embedded in reflective paint, we’re seeing the internal reflections from pebbles and cobbles of ice, as big as tennis balls or even footballs, lining Titan’s river beds.