Question

What evidence did copernicus use to explain that the sun is at the center of the solar system?

Answer 1

Copernicus used two main pieces of evidence to support his assertion that the sun is at the center of the solar system:

1. Retrograde motion: Copernicus observed that at certain times of the year, the outer planets (Jupiter, Saturn, etc.) appeared to move backward in the sky, known as retrograde motion. This motion was difficult to explain if one assumed that the Earth was the center of the universe, as the planets would need to move in complicated loops.

2. Relative brightness: Copernicus also noted that the planets appeared to vary in brightness throughout the year. This could be explained if the planets were revolving around the sun at varying distances, as they would appear brighter when they were closer to Earth and dimmer when they were farther away.

Using these observations, Copernicus proposed a heliocentric model of the solar system, in which the sun is at the center and the planets revolve around it in circular orbits.