Basic objective of this lecture is to present on Geocentric vs. Heliocentric System. Geocentric System narrate: the Sun, stars, and planets on their spheres revolve around the earth: explains daily movement; to account for unusual planetary motion epicycles were introduced. Heliocentric System describe how moon orbited the earth, the earth orbited the sun as another planet; how Planets and stars still on fixed spheres, stars don’t move.