Hello, One or two years ago I had a mathematics lecture where one part of it was using basic formulae, a pendulum and the distance to the centre of the earth to find out what the distance to the sun was. Recently, I came across a question which asked me to figure out the distance to the sun however it was far more complicated and used more advanced theories than the example I was shown in the lecture. However, I can no longer precisely remember how to do it using the method in the lecture but I can remember that it involved finding the distance to the centre of the earth, how far the horizon of the earth was and a pendulum to find the distance to the sun. If you know of a method along these lines, please could you inform me? It would be greatly appreciated, thanks.