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Copernicus publishes his heliocentric theory of the Universe in Poland, 1543.
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Tycho Brahe discovers a supernova in constellation of Cassiopeia, in Denmark. Not that Casiopeia is in Denmark he discovered these things while in Denmark.
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Galileo uses telescope for astronomical observations. Galileo didn't invent the telescope but he was among the first to use a telescope to examine the heavens. He carried out important observations of the Sun, Moon, Planets, and Stars.
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Kepler discovers laws of planetary motion. Working with Tycho's observations, Kepler discovers the shapes of planetary orbits, how the speed of a planet varies as it orbits the Sun, and the relationship between orbital distance and orbital period.
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Cassini notes Martian polar ice caps in Italy, 1666.
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James Gregory makes the first realistic estimate of the distances of the stars. Gregory assumed that the other stars were just as bright as the Sun and then calculated how distant they had to be to match their apparent brightnesses.
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Newton publishes his theory of universal gravitation in the work Philosophiae Naturalis Principia Mathematica. This is seen to be the start of Modern Astronomy. This happens in England.
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Hubble Space Telescope put into orbit from space shuttle Discovery. United States.
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Pope John Paul II announces that the Catholic Church revokes its condemnation of Galileo.
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Comet Shoemaker Levy crashes into Jupiter.