Evidence for Earth Orbit about Sun
What evidence was used to prove Earth revolves around the sun?
Historically, there were two opposing theories: a heliocentric system (the
Sun at the center of the universe) and a geocentric system (the Earth at the
center of the universe). The geocentric theory was slowly eroded by many
different observations: Mars and Jupiter were shown to have moons - and so
the Earth was really not the true center if moons revolve around other planets;
the planets themselves (meaning "wandering") could not be placed in any kind of
circular or elliptical orbit - they seemed to move back and forth in the night
sky (hence the name); Venus was observed to have a full set of phases just like
the moon - which was a strong argument against Venus revolving around the Earth.
Ultimately, when physics united with astronomy, it could be shown that the
mathematical predictions closely followed celestial observations - and this
fit more with the ideas of heliocentricity.
Greg (Roberto Gregorius)
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Update: June 2012