The first (upper) model is geocentric system and the scientist is Ptolemy.
The second model is heliocentric system and the scientist is Copernicus.
<em>Ptolemy's model </em>( earth-centered) : all celestial objects including the planets, sun, moon and the stars orbited (rotated around) the earth. The earth was in the centre of the universe and it did not move at all. On this chart, the planets Uranus and Neptune are missing because they had not been discovered yet.
<em>Copernicus' model </em>( sun-centered) : All the planets orbited the sun and the moon orbited the earth. The sun was in the centre of the universe and did not move at all.
Both Ptolemy and Copernicus thought that the orbits of the planets were circular but, in fact, they are elliptical.
