The development of world models
Geocentric model – 140 after Christ
The Greek astronomer Claudius Ptolemy (ca. 100-160 after Christ) took up the geocentric world model and tried to improve it. For this, he added additional auxiliary circles (epicycles) for explaining the visible loop movements of planets. The earth is in the centre. Sun, moon, planets and stars orbit them.
Heliocentric model – 1543
Nicolaus Copernicus (1473-1543) published the heliocentric world model already in 1543. He positioned the sun in the centre of the system while the planets and the earth with the moon orbit it in simple circular paths. Still, it was only by the end of the 17th century that the heliocentric world model became generally accepted.
Tychonic model – 1588
Tycho Brahe’s measurements (1546-1601) showed that planets moves around the sun. The starry sky may create new things. Comets do not belong to the atmosphere. He did not dare to change the position of the earth in the centre of the planetary system. Thus, the sun, together with the planets, orbits around the earth in his world model.