I was thumbing through the remarkable observations set down by Nicolaus Copernicus in his book On the Revolutions of Heavenly Spheres in the 1400s.  You may recall that Copernicus abandoned the long-held Ptolemaic system, where the Earth was seen as being fixed in the center of the universe (geocentric) in favor of his mathematical proof that it in fact moved around the sun (heliocentric).    …

Continue reading On the Revolutions of Heavenly Spheres by Nicolaus Copernicus