Referring to the Figuring Physics “With Simply a Pair of Sticks” in the September 2018 issue of TPT (p. 361) and its answer in the October 2018 issue (p. 483), I hypothesized: The size of any spherical body in overhead sunlight can be calculated by the shadows cast by a pair of vertical sticks a known distance apart in any direction. A caveat in the Figuring Physics piece was that the shadow of one stick points to the other stick. This resulted in simple planar geometry, wherein the parallel shadow-casting sunbeams lie in the same plane as the two-sticks’ great circle. To calculate the circumference of the sphere, one only needs to know the angle of the vertex at the sphere’s center where vertical extensions of the sticks meet. Because of this coincidence of planes, the difference in shadow angles equals the vertex angle at the sphere’s center. (Or, if...

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