For a moment if I assume that I know nothing about the universe, and I set in to observing what’s happening around me. Definitely I would get the following observations:
1) Everyday the sun rises from a particular direction and it sets in a particular direction.
2) Night sky has some pattern for the stars and their motion is similar to that of sun.
The natural thought that would be striking one’s mind is that the sun is coming back and forth everyday and thus, it should be revolving around Earth. In ancient times, sun was a symbol of god i.e. it stands for immense power and it seemed valid to those people to hear that the god is around us. Some of you might be aware with the name of Ptolemy. He was a brilliant astronomer of his time and he believed in this theory based on the observations I just talked about.
This belief was never questioned till Nicholas Copernicus. He explained the planetary motion like Ptolemy did. However the big difference in his hypothesis was, he placed sun at the center instead of Earth. This daring conclusion of his, annoyed many people as he had placed their god at rest. The kind of mindset, which had been developed by Ptolemy for so many years, was hard to swept away in a moment. It took many years for people to understand that Earth was just a planet like the Mercury, Venus, Mars and Jupiter (only 5 were known at that time). However, it was unfortunate for Copernicus that his hypothesis was not accepted by people at his time. Later on, it was Kepler who proved these facts along with his laws of planetary motion. This was certainly an achievement of science and observation that without going into outer space, we had decoded it.