One of things I like to think about in science is "how do we know that?"  It is interesting how one thing builds on another. This is a story of how the Greeks estimated the distance from the Earth to the Sun (an important idea in the development of the model of the solar system).  I like this story because it is not too complicated.  In fact, one could easily reproduce these measurements themselves.  So, here is what I will talk about:
Measuring the size of the Earth.
Determining the distance from the Earth to the moon and the size of the moon.
Calculating the distance (and size) to the Sun…