Unfortunately, the system that was out there in Ptolemy’s time did not quite match observations, although it was considerably improved over Hipparchus’ system. Most noticeably the dimensions of a planet’s retrograde loop (especially that of Mars) can be smaller, and generally bigger, than anticipated, leading to positional errors of as a lot as 30 levels.

In the Copernican model, the Earth orbits the Sun together with all the other planets. Such a model can explain the retrograde motion of a planet without resorting to epicycles, and also can explain why Mercury and Venus by no means stray more than 28° and forty seven° from the Sun.

Meaning “earth centered,” it refers to orbits around the earth. In ancient instances, it meant that the earth was the center of the universe.

Ethnocentric, Geocentric, And Polycentric

He lived in Alexandria, Egypt which was a significant heart of knowlege of the traditional mediteranean. … Read More

Read More »