The Ptolemic model was not better at the time, but it wasn't really worse. The Copernican model provided roughly the same observational accuracy, and was very slightly simpler. Occam's razor would probably prefer the Copernican model in a vacuum, but the differences were too slight to prefer unseating the incumbent.
> Copernican model is also wrong, planets are orbiting around center of gravity, which is outside of sun..
Well, a bigger shortcoming is that Copernicus still insisted that orbits be circles instead of ellipses.
> Ptolemaic model with its epicycles provided better predictions.
Not only did the Copernican model include epicycles, it actually included more epicycles than the Ptolemic model (modern myth notwithstanding). Both models could improve accuracy by adding more epicycles, and for the same amount of computation, both models produced predictions of roughly equal accuracy.
The one improvement the Copernican model provided, was that it removed something called the equant (and replaced it with more epicycles). The equant allows for non-constant orbital velocity around an epicycle, by instead having constant angular velocity around a point that is not the center of the circle. When Copernicus' work was published, the removal of the equant was considered by many mathematicians to be the main argument in favor of heliocentrism (although some considered it just a computational model, with geocentrism still being correct with respect to reality).
> Copernican model is also wrong, planets are orbiting around center of gravity, which is outside of sun..
Well, a bigger shortcoming is that Copernicus still insisted that orbits be circles instead of ellipses.
> Ptolemaic model with its epicycles provided better predictions.
Not only did the Copernican model include epicycles, it actually included more epicycles than the Ptolemic model (modern myth notwithstanding). Both models could improve accuracy by adding more epicycles, and for the same amount of computation, both models produced predictions of roughly equal accuracy.
The one improvement the Copernican model provided, was that it removed something called the equant (and replaced it with more epicycles). The equant allows for non-constant orbital velocity around an epicycle, by instead having constant angular velocity around a point that is not the center of the circle. When Copernicus' work was published, the removal of the equant was considered by many mathematicians to be the main argument in favor of heliocentrism (although some considered it just a computational model, with geocentrism still being correct with respect to reality).