The earth was in the middle of the solar system. The stars, the moon, and the sun all revolving around it! But then unlike the other and previous geocentric model of the solar system, Tycho's model of the solar system had all the planets going around the sun, Tycho's observations had been the most accurate than any other ones made before he made his. The accuracy of his observations let Johannes Kepler deduce his three laws of planetary motion, without Tycho looking out into the sky and making accurate observations, Kepler would have never discovered that the planets move in an elliptical orbit.
