The scientific theory or belief system that the sun is at the center of the universe, with planets and celestial bodies orbiting around it.
From heliocentric plus '-ism' suffix (creating abstract nouns for belief systems or theories), developed as a formal counterpart to geocentrism.
Heliocentricism was basically heresy in the 1500s—promoting it could get you in serious trouble with church authorities, which is why Copernicus waited until he was dying to publish!
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