Astronomy By Mackenzie Martin Apr 29, 1543 Copernicus publishes his heliocentric theory of the Universe. Occured in Poland Apr 29, 1609 Galileo uses telescope for astronomical purposes. He discovers 4 Jovian moons, the Moon's craters and the Milky Way galaxy, in Italy. Apr 29, 1619 The Third Law of Planetary Motion is announced by Kepler in his work Harmonice Mundi (Harmony of the World). Germany Apr 29, 1781 The discovery of Uranus by Herschel England Apr 29, 1877 Schiaparelli observes the canals on Mars. Mars Apr 29, 1959 Huygens notes markings on Mars. Netherlands Apr 29, 1986 Space Shuttle Challenger disaster U.S.A. Apr 29, 1995 Galileo space probe reaches Jupiter. Near Jupiter Apr 29, 1998 Galileo discovers origin of Jupiter's Rings Jupiter Apr 29, 2000 New evidence found for water on Mars. Mars