Copernicus worked for years on his book describing his theory, and published it near the very end of his life. He entitled it, "De revolutionibus orbium coelestium" ("On the Revolutions of the Heavenly Spheres"), and published it in 1543. The major parts of Copernican theory are: | Copernicus worked for years on his book describing his theory, and published it near the very end of his life. He entitled it, "De revolutionibus orbium coelestium" ("On the Revolutions of the Heavenly Spheres"), and published it in 1543. The major parts of Copernican theory are: |