It is always cool to repeat classic experiments. How many of us know the radius of the Earth because we determined it on our own? I haven't done this, at least not yet. For all my life I have just ...

After 10 years I think my absence of a mathematical education has finally come to hurt me in a programming setting. I need to calculate the distance between two points on Earth using a Great Circle ...

I don't know where he got this idea (surely not from the internet), but Eratosthenes estimated the radius of the Earth by looking at two shadows at two different locations on the Earth. This diagram ...