On Monday, June 24, 2013 1:28:01 PM UTC+1, Martin Brown wrote:

And it took over 2000 years to get from the Greek philosophers rough and

ready explanations of the universe to where we are now.

You are thumbsucking Brown and your days dominating astronomy are numbered..The Greeks designated the name 'planet' to objects that wandered against the stellar background as opposed to the Sun and motion which appeared to travel in a straightforward path.One of those Greeks even came close to identifying the Earth double motion using declination as a basis for orbital motion and daily rotation to account for the noon cycle -

"Only,” replied Lucius laughing, “do not bring an action for impiety against us, just as Cleanthes thought it right that the Greeks collectively should impeach Aristagoras the Stoic, of impiety, for overthrowing the altar of earth, because the fellow attempted to account for visible phenomena by supposing that the sky remains fixed, and that the earth rolls round down an oblique circle, turning at the same time upon its own axis."

http://thriceholy.net/Texts/Moon.html


The great innovation of Copernicus was identifying what the wandering motions of the planets are however now you may appreciate the difference between retrogrades of the inner and outer planets and their separate cause seen from a moving Earth -

http://www.youtube.com/watch?feature...&v=MdFrE7hWj0A

http://www.masil-astro-imaging.com/S...age%20flat.jpg

A simple motion by turning your screen 90 degrees and watching Mercury swing out from behind the Sun and now traveling back in is how astronomy is appreciated and practised.

Carry on chanting voodoo of dark matter,string theory and big bang,genuine astronomy is about to make a comeback in the most spectacular fashion.