Astronmy Essay Example | Topics and Well Written Essays - 500 words

Astronmy - Essay Example The planets appear to be varying in brightness since they are not always at the same distance from the earth Earth centered universe was proposed by ancient Greek philosophers, Aristotle and Ptolemy. All heavenly bodies are attached to 56 concentric spheres which rotate around the Earth. In their superseded theory of geocentric model, they assumed that earth is at the centre of universe and all planets and stars like sun revolves around the earth. The Greeks were also believed that the motion of the planets were circular and not elliptical. They also believed that the stars were circling around the poles and the stars near the equator rising and setting each day and circling back to their rising point. Polish astronomer Nicolas Copernicus was the first who put forward the sun centered universe theory which is known as heliocentric theory in the 1514. This theory assumes sun at the centre of the universe and all other planets revolving around it except moon. He was successful in predicting the earth’s third place in the solar system. He also believed that the shape of the orbit in which the planets revolving around the sun is not exactly circular. â€Å"Sometimes Mars went forward, other times it slowed down or went backwards. If the planets all revolved around the Earth, why didnt Mars orbit in a uniform way?† (Dean Regas) This idea actually questioned the authenticity of earth centered universe model and encouraged Copernicus to formulate his famous heliocentric theory. Earth centered universe concept was an ancient theory formulated mainly by some Greek philosophers like Aristotle, Ptolemy, Plato etc. Observations seem to reinforce this view. The Sun rises in the east and sets in the west. Stars in the north spin counterclockwise around the North Star. And the Earth appears to be the only thing that doesnt move. (Dean Regas) They argued that if the earth did move, then one