1543: Heliocentrism - The book of science

Heliocentrism
Consistency
Without a center
Commentary

Heliocentrism

As Nicolaus Copernicus
said in his book
On the Revolutions
of the Celestial Spheres,
Moons and planets
orbit more than one center.
Only the moon
orbits the earth.
The celestial spheres
orbit the sun.
The firmament moves
because the earth turns.
The seasons change
because the earth wobbles
as it orbits the sun.
Planets sometimes appear
to move backwards
only because the earth moves.
Earth’s distance to the sun
is insignificant compared
to the sun’s distance to the stars.

Consistency

Copernicus changed the center of the universe
but otherwise retained Ptolemaic errors.
His celestial objects sit in crystalline spheres.
His orbits are circular or compounded of multiple circles.
His planets move at a uniform speeds.
Copernicus defended his system
because it was geometrically simpler.

Without a center

We may not have our planet
as the stationary center of an eternal universe.
Nor may we have our sun as such.
Our solar system is only part
of a Milky Way galaxy in flux,
and ours is only one of many galaxies
drifting without a center.
William Herschel thought the craters of the moon
were circular cities for a lunar race,
and ours was only one of many peopled worlds
in which, like ours, I say, every adult must act
as if he or she made his or her own decisions
according to his or her own sense of what is right.

Copernicus was not the first person to propose a heliocentric universe; however, Copernicus provided a predictive mathematical model.

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.