Heliocentrism Consistency Without a center Commentary

Nicolaus Copernicus astronomy

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.