Copernicus was not the first person to propose a
heliocentric universe; however, Copernicus provided a predictive
Copernicus placed the center of the universe near but not at
the sun. Understanding how gravity controls the orbits of planets
and moons escaped him, as well as Kepler and Galileo.
Andreas Osiander wrote an preface for the first edition of De
revolutionibus orbium coelestium that stated that the Copernican
theory was not intended as a description of the literal truth but
only as a simpler mathematical description of astronomical
observations to improve the calendar.
See also in The book of science:
Readings on wikipedia: