Look similar?

The top image shows sand dunes in Africa's Namib Desert, and the bottom reveals similar dunes on Saturn's largest moon, Titan, in a photo taken last October by NASA's Cassini probe. According to this article in National Geographic, Titan's dunes came as somewhat of a surprise: Because solar energy drives wind and Titan gets one thousandth as much solar heat as Earth, no one expected to see evidence of such strong currents. So where'd they come from? Scientists think that Saturn's gravity creates tidal winds that do the job.