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Copernicus publishes his heliocentric theory of the Universe.
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Galileo uses telescope for astronomical purposes. He discovers 4 Jovian moons, the Moon's craters and the Milky Way galaxy.
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Kepler's First and Second Laws of Planetary Motions are announced.
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the Third Law of Planetary Motion is announced by Kepler in his work Harmonice Mundi (Harmony of the World).
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Christian Huygens discovers Saturn's rings and Titan, the fourth satellite of Saturn.
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The first reflecting telescope was built by Newton.
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Geminiano Montanari discovers the star Algol is not steady in brightness, thus recognizing the first variable star.
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While in Paris, Danish astronomer Ole Romer measures the speed of light.
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Cassini discovers that Saturn's rings are split into two parts, so that today the gap is called the "Cassini Division".
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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.
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Halley correctly predicts the return of a comet (Halley's comet) in 1758.
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Johann Palitzsch observes Halley's comet as predicted by Halley in 1705.
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The discovery of Uranus by Herschel
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Tsiolkovskii's work in early rocketry earned him the title of "Father of Astronautics". Many of his proposals concerning rocketry were later put into use including: use of liquid hydrogen and liquid oxygen as rocket fuel and multi-stage rocket design for achieving Earth orbit or interplanetary flight.
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The Great Red Spot on Jupiter becomes prominent.
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Robert Goddard begins practical rocketry.
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Hubble shows that galaxies exist outside the Milky Way galaxy.
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Sputnik, first object to orbit the Earth, launched by the Russians.
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Explorer 1 launched. This was the first U.S. satellite to orbit the Earth.
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John Glenn becomes first American man to orbit Earth.
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Hubble Space Telescope put into orbit from space shuttle Discovery.
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The Vatican under Pope John Paul II announces that the Catholic Church erred in condmening Galileo's work that proved that the work of Copernicus was valid, mainly that the planets circle the Sun and not the Earth.