Dear all!

I enjoy listenning to these lectures. I determined to watch all of them, watching the video file and the pps file simultaneously. Switching between them all the time. (Alt+tab)

I've just stuck here with counting...

In the 10th lecture you can see Kepler's laws. The third one is quite simple. (see: 14th pic or 22:09 in the vid) It is a simplification of the REAL Kepler's 3rd law (

http://en.wikipedia.org/wiki/Kepler%27s_laws_of_planetary_motion see Deriving Kepler's third law ). Still, it becomes fuzzy when Mr. Nemiroff starts to count. (25:57) Somehow it is not OK. Firstly you may think that because he misses the "/M" part of the formula. But the formula is actually wrong. "/M" needn't be there. And what's then? Still wrong result you get. Because the official radius is estimated from the Perihelion (closest to the Sun) and the Aphelion (furthest from the Sun). It is the mean of these numbers.

(Q + q)/2=r

r=(2.544+2.987)/2=2.7655

Mr. Nemiroff supposes, that the ellipticity (~excentricity) is the problem. So it is. But It wasn't so convincing...

I still enjoy this course, and looking forward for more "fun stuff" as he calls it. I mean counting.

Smallfish

from Hungary