sun and moon scope
Arguments in the debate
Quite a few arguments were put forward:
This phenomenon can be seen everyday: see the animation to the right. When you move (like in a train), objects far away seem to move slower than objects nearer to you.
Stellar parallax can only be observed with good telescopes because of the distance of the stars. How it works is explained in the picture below to the right.
He was very good in math. Using the exact observations of Tycho he could not get his calculations right assuming planets were orbiting in circles - as was assumed to be perfect, divine movement (a Greek thought). He concluded the planets orbit the Sun in ellipses and proposed some famous laws (used by Newton for his laws). He is considered to be one of the founding fathers of modern science.
His contribution to the discussion seems to be vital. Two of his laws are essential:
Planets orbit around the Sun because of the law of gravity - the Sun being the largest.
You do not notice speed because of the law of inertia: nothing changes speed unless a new force is applied upon it. We experience this in a plane cruising over the Atlantic at 900 kms/h.