You can use the Sphere icon to measure the diameter, sphericity, and position of the center of a sphere.

To create a measured sphere you must take a minimum of four hits. The points to be picked must be uniformly distributed over the surface. The first four points picked must not lie on the same circumference. The first point should be taken on the pole of the sphere's cup. The other three points are taken on a circumference.

Example Sphere with 5 Points

Example Sphere with 9 Points

For information on the associated Edit window command, see the "Basic Measurement Format for a Sphere" topic in the "Creating Measured Features" chapter.