The reason why copernicus' heliocentric theory soon came to be regarded as preferable to the geocentric theory of ptolemy is that the heliocentric theory

Copernicus's theory stated that the earth and other planets revolved around the sun while Ptolemy's theory said that the sun went around the earth. Copernicus's theory was further expanded when Newton discovered gravity and because of that a lot of pieces fell in place which is why the heliocentric theory was favored.