Saturn's hexagon change in season. These changes were observed by the Cassini spacecraft. One hypothesis, developed at Oxford University, is that the hexagon forms where there is a steep latitudinal gradient in the speed of the atmospheric winds in Saturn's atmosphere. Similar regular shapes were created in the laboratory when a circular tank of liquid was rotated at different speeds at its centre and periphery. The most common shape was six sided, but shapes with three to eight sides were also produced. The shapes form in an area of turbulent flow between the two different rotating fluid bodies with dissimilar speeds. A
Shoulder plane for joinery. Unlike the rebate plane, the shoulder plane is intended to cut end grain. There are therefore differences between it and a rebate plane in the angles at which the iron (blade) is set. A shoulder plane also has a much finer set mouth, which allows finer shavings to be taken. Shoulder plane The shoulder plane (also bullnose plane) is a plane tool with a blade flush with the edges of the plane, allowing trimming right up to the edge of a workpiece. Like a rebate plane, the shoulder plane's blade extends, therefore cuts, to the full width of