The Cassini orbiter has imaged a wierd hexogonal structure at Saturn's north pole.
In the new infrared images, the strong brightness of the hexagon feature indicates that it is primarily a clearing in the clouds, which extends deep into the atmosphere, at least some 75 kilometers (47 miles) underneath the typical upper hazes and clouds seen in the daytime imagery by Voyager. Thick clouds border both sides of the narrow feature, as indicated by the adjacent dark lanes paralleling the bright hexagon. This and other images acquired over a 12-day period between Oct. 30 and Nov. 11, 2006, show that the feature is nearly stationary, and likely is an unusually strong pole-encircling planetary wave that extends deep into the atmosphere.I looked up "planetary wave", also known as a Rossby wave, and found it is a type of inertial wave possible in rotating fluids. Unlike the waves we're familiar with at the beach, an inertial wave travels through the bulk of the fluid, not the surface. Cool.