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
A Plane Is Born training at Staverton Airport in Gloucestershire with instructor Carl Bowen. - Building Begins Mark learns that before he starts to build his aeroplane he must attend a workshop on composite building techniques. His crash course is instructed by expert Neville Eyre. In part 2, back at the workshop, he begins work on his kit plane, starting with the Rudder. Some respite from plastics is provided at Gloucester airport where his flying training continues apace. In a regular feature, Dudley Pattison shows us the Isaac's Fury biplane he took fifteen years to build. - Wings Filming in the workshop, work begins