Question

How would Ptolemy explain the rising of the Sun? Contrast this to Copernicus's explanation of the same event.

Answer 1

According to Ptolemy, earth stayed stationary while the Sun revolved around the earth from east to west. This is why he thought Sun rises in the east and sets in the west. Ptolemy's model is also known as the geocentric model and he thought that all celestial bodies, e.g. the sun and the moon orbited the stationary earth.

But now we know the above explanation to be incorrect. Copernicus explained correctly that in our solar system the Sun remains stationary while all the planets, including Earth, revolves around the Sun. Hence this model is also known as heliocentric. In addition to the revolution around the Sun, Earth also rotates eastward about its axis once a day. Because of this, the Sun appears to move from east to west from the point of view of an observer on Earth.