Wearing of the Sphere

This is a kids' playground item at Wheaton Regional Park in Maryland. It's a toy/chair/apparatus that is basically a painted sphere on a pedestal. Children sit, slip off, or perhaps spin around, balancing on top of the sphere. This produces the wear pattern contours shown here. The central circular region has the most paint rubbed off, down to the metal interior. Around this is a ring of lesser wear. The circular nature of the contours indicates that the children don't seem favor one approach to sit, one method of sitting, or one direction of dismounting the sphere. No one direction of wear seems overly favored, or avoided, even though the light ring of lesser wear may not have exactly equal width around the contour. What remains are the circular contours of the frequency of use of a distribution defined on a sphere.