The mystery deepens with the unusual light and dark hemispheres of Iapetus. One side is as white as snow, and the other is as black as tar. With the new Cassini images, you can actually see where the different regions mix. On the dark side, you can see spots where there are patches of white ice on dark mountainsides. And then on the bright side, you can see blobs of dark material. This dark material forms a very thin coating; probably only a few metres deep, since there are regions where impact craters have punched right through it, revealing white material underneath.