Scientists have used data from the Cassini radar mapper to map the global wind pattern on Saturn's moon Titan using data collected over a four-year period, as depicted in this image. The arrows indicate the direction in which sand is inferred to be transported along dunes observed in Titan radar data. Underlying the arrows is a base map from Cassini's imaging science subsystem. Many of the equatorial dark areas without arrows might have dunes but have not yet been imaged with radar. The dune orientations represent only the net effect of winds. It could be that sand transport only occurs on rare occasions, and winds from different directions can combine to yield the observed dune orientations.