Natural Blogarithms

While substituting for a colleague in Modern Geometry, we were reviewing several theorems regarding circles and doing some constructions with compass and ruler. At one point I presented a theorem on the fact that a tangent line to a circle is perpendicular to the line passing through the center of the circle and the point of the tangent. We also demonstrated that the converse is true: any line that passes through a point on a circle that is perpendicular to the through that point and the center must be a tangent.[...]

This was fascinating: A photographic list of all the bodies in our solar system that are larger than 200 mi in diameter. By the way, I particularly like the name of the objects beyond Neptune: “Trans-Neptunion Object (TNOs)” [...]