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Aristarchus suggests the Earth revolves around the Sun. He provides first estimation of Earth-Sun distance.
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Eratosthenes measures the circumference of the earth with surprising accuracy!
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Hipparchus develops the first acccurate star map and star catalogue with over 850 of the brightest stars.
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Astronomers observe supernova in Taurus.
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Tycho Brahe discovers a supernova in constellation of Cassiopeia.
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Hans Lippershey, a Dutch spectacles maker invents the telescope.
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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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Galileo was considered the father of observational astronomy. He was among the first to use a telescope to observe the sky and after constructing a 20x refractor telescope he discovered the four largest moons of Jupiter in 1610. This was the first observation of satellites orbiting another planet.
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Christian Huygens discovers Saturn's rings and Titan, the fourth satellite of Saturn.
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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
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The discovery of Uranus by Herschel
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Messier discovers galaxies, nebula and star clusters while looking for comets.
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Piazzi discovers first asteroid, Ceres.
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Johann Galle observes and discovers Neptune
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Asaph Hall discovers Phobos and Deimos, the moons of Mars.
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Hubble shows that galaxies exist outside the Milky Way galaxy.
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First radio telescope built by Grote Reber.
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April 12 was already a huge day in space history twenty years before the launch of the first shuttle mission. On that day in 1961, Russian cosmonaut Yuri Gagarin (left, on the way to the launch pad) became the first human in space, making a 108-minute orbital flight in his Vostok 1 spacecraft.
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John Glenn becomes first American man to orbit Earth.
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On June 16, 1963, aboard Vostok 6, Soviet Cosmonaut Valentina Tereshkova becomes the first woman to travel into space. After 48 orbits and 71 hours, she returned to earth, having spent more time in space than all U.S. astronauts combined to that date
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Armstrong and Aldrin walk on the Moon as part of Apollo 11 mission.
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The U.S. launches Pioneer 10, the first satellite destined for Jupiter.
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Discovery of Uranus' rings
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Construction begins on the International Space Station.
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Space Shuttle Endeavor makes a detailed, global map of Earth
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New evidence found for water on Mars.