Johannes kepler, an apprentice of brahe, believed in the heliocentric universe but rejected past astronomers' belief in

So the question is in what did johannes Kepler reject since he believed in the heliocentric universe. So heliocentric system is a system where the sun is in the center of the Solar system. Geocentric system is the system where Earth, not Sun is in the center of our system. He was against Geocentric system.