The Saturn hexagon is a persistent hexagonal cloud pattern at the north pole of Saturn. The radius of the hexagon is approximately 8,600 miles, with a rotation period of 10:39:24. While a variety of explanations have been offered for the hexagon, It is generally thought to be some sort of standing wave phenomenon generated by differences in wind speed around the pole.
Interesting article from Science's popular science outfit about the Saturnine hexagon. While it is certainly an intriguing development, and a step forward from the well-known "spinning bucket" experiments, they should get back to us when they've made a hexagon 15,000 miles wide that lasts for 30 years. (Which, for practical purposes, one wouldn't expect any time soon.) Fluid dynamics can be vastly different at different scales. I would also like to know what the viscosity is of this "water" they speak of relative to the atmosphere of Saturn.