Aristotle, Ptolemy and Nicolaus Copernicus, from an edition of Galileo's 'Systema Cosmicum' ('Cosmic System') published in London in 1663. Polish astronomer Copernicus (1473-1543) originated the theory of the Sun-centred universe, in which the Earth is merely one of the planets revolving around the Sun. It had previously been believed that the Earth was the centre of the universe. Italian astronomer and physicist Galileo Galilei (1564-1642) based his work on Copernicus' heliocentric theory, and is one of the greatest scientists of all time. Among his achievements was the discovery of Jupiter's moons and the laws governing falling bodies. His work was seen as heretical by the Catholic church and Galileo was imprisoned by the Inquisition.
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