Photogravure after a woodcut. Copernicus (1473-1543) is considered to be the 'father' of modern astronomy and founder of heliocentric cosmology. Prior to the work of Copernicus, the Earth was considered to be the stationary centre of the universe, a notion first advocated by the Egyptian astronomer Ptolemy (c 90-168 AD). His pioneering work 'The Revolutions of Celestial Spheres' (1543) describes his idea of a Sun-centred universe, in which the Earth is merely one of the planets revolving around the Sun and rotating on its axis.
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