Re: Historical determination of the astronomical unit (again)

[DrArthurCarlson]

In einer eMail vom 13.6.2004 20:50:17 Westeuropäische Sommerzeit schreibt [EMAIL PROTECTED]: 1. How does it solve for the astronomical unit, the absolute distance from the earth to the sun? I understand that it solves for the ratio of the distances earth to sun and earth to moon, but not the absolute distance. There is no base line to triangulate for actual distance. Right. You still need to factor in the distance to the Moon. There is a baseline for that, namely the diameter of the Earth. I have to admit I'm not clear on the details, though, and it might prove as difficult in practice as the other problem, once you start thinking about it. 2. How does it demonstrate heliocentricity? The moon rotates around the earth but are not the triangles the same if the sun revolves around the earth or the earth resolves around the sun? It doesn't really, except very indirectly. If you argue (with Aristotle?) that the Earth is too big to move, then, if the sun is umpteen times bigger, then it must really not move. (Which is not such a bad argument, when you get down to it.)   --Art Carlson