General objective of this lecture is to present on the Copernican Revolution. In the heliocentric or copernican model, apparent retrograde motion of the planets is a direct consequence of the Earth’s motion. The story of Copernican Revolution is the classic example of a major shift in worldview. In a book called On the Revolutions of the Heavenly Bodies, Copernicus proposed that the Sun, not the Earth, was the center of the Solar System. Such a model is called a heliocentric system.