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The Big Bang is thought to have happened


2800 The construction of Stonehenge is started. It was completed around 1000 BC (UK)

~2,000 B.C

280 Aristarchus had the idea that the Earth revolves around the Sun, the Heliocentric Hypothesis. (Samos, Greece)




240 Eratosthenes makes a near accurate measurement of the circumference of the Earth. (Cyrene, now in Libya)



140 Hipparchus classed over 850 stars by their brightness, into 6 groups or magnitudes. (Greece)

140 Ptolemy put forward the theory that all the planets and the Sun orbit the Earth. This is called the Geocentric Theory and it was believed for around 1500 years! (Eygpt)



1543 Copernicus publishes "On the Revolutions of the Celestial Spheres" (Poland)


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1572 Tycho Brahe observes a "new star" in the Cassiopeia constellation. (Denmark)


1582 Pope Gregory XIII introduces a new calendar, the Gregorian Calendar (Italy)

1596 David Fabricius discovers Mira, the first known periodic variable star. (Frisia, now Germany)

1603 Johann Bayer publishes Uranometria that introduced a new way of representing stars by assigning Greek letters to each of them. (Germany)

1609 Galileo uses a telescope to look at the night sky. He discovers the Milky Way, craters on the Moon and the moons around Jupiter.(Italy)

1611 Johannes Fabricius identifies sunspots. (Germany)



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1608 Han Lippershey, a spectacle maker, invents the telescope (Netherlnds)

1609 Kepler publishes Astronomia Nova, that describes his frist two laws of planetary motion.(Germany)

1619 Kepler publishes Harmonice Mundi (Harmony of the World)that describes his third law of planetary motion. (Germany)

1656 Christiaan Huygens discovers Saturn's fourth moon, Titan, and identifies Saturn's rings. (Netherlands)
1666 Giovanni Cassini measured the period of rotation of Mars and identified its polar ice caps. (Italy)
1676 Ole Roemer, a Danish astronomer living in Paris, while observing the moons of  Jupiter, discovers that light has a speed. Measures the speed of light at 200000 Km/sec (France)
1687 Newton publishes is book about Universal Gravitation,  Philosophiae Naturalis Principia Mathematica. This is considered the start of Modern Astronomy. (England)




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1659 Christiaan Huygens records features on the surface of the planet Mars. (Netherlands)

1668 Newton built the first reflecting telescope. (England)
1669 Geminiano Montanari discovers the brightness of the star Algol is variable.(Italy)
1675 Cassini identifies a gap in the rings of Saturn, now called the "Cassini Division". (France)
1705 Halley predicts that a comet will return in the year 1758. This comet is now known as Halley's comet. (England)

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1758 Halley's comet is observed by the astronomer Johann Palitzsch on the night of December 26-27, 1758. (Germany)


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1781 William Herschel discovers Uranus. (UK)

1781 Charles Messier catalogues the Messier Objects (galaxies, nebulae and star clusters) he discovers. (France)
1801 Giuseppe Piazzi discovers the asteroid, Ceres. (Italy)
1843 Samuel Heinrich Schwabe recognises sunspot cycles. (Germany)


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1842 Christian Doppler discovers the "Doppler Effect". (Austria)

1846 Johann Gottfried Galle discovers Neptune. (Germany)

1860-1863 Sir William Huggins studies the chemical composition of stars using spectral analysis. (UK)
1877 Giovanni Schiaparelli observed lines on the surface of Mars. These were later called "Canals". (Italy)
1878 The Great Red Spot on Jupiter is named. During this year it increases in size.


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1868 Pierre Janssen and Norman Lockyer used the spectroscope to study solar prominences. (UK)

1872 Henry Draper photographs a stellar spectrum. (US)

1877 Asaph Hall identifies the moons of Mars, Deimos and Phobos. (US)
1904 Mount Wilson Observatory is founded. Its prime objective is to study the sun. (US)
1908 Ejnar Hertzsprung indentifies giant and dwarf stars. (Denmark)
1911-1914 Ejnar Hertzsprung and Henry Norris Russell build a diagram that plots the stars brightness against their temperature. This is called the HR diagram. (Denmark & US)
1916 Albert Einstein publishes his general theory of Relativity (Germany)
1926 Robert Goddard uses liquid rocket fuel to power a test rocket. (US)
1930 Clyde Tombaugh discovers Pluto (US)
1937 Grote Reber builds the first radio telescope (US)




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1905 Albert Einstein publishes his special theory of Relativity (Germany)

1908 Henrietta Swan Leavitt discovers stars that go through cycles of brightness and darkness, the cepheid variables. (US)

1914 Robert Goddard launches a ten foot rocket that begins the rocket era. (US)

1923 Edwin Hubble identifies galaxies other than the Milky Way (US)
1927 Jan Oort showed that the Milky Way galaxy rotates (Netherlands)
1931 Karl Jansky discovers radio waves that are extra-terrestrial in origin (US)
1957 Sergei Korolyov launches Sputnik, the first satellite to orbit the Earth (Russia)
1960 Archaeoastronomy, the study of the history of astronomy, is introduced (UK)
1962 John Glen pilots the Mercury- Atlas 6 ("Friendship 7) spacecraft into a three-orbit flight around the Earth (US)
1966 Luna 9 makes the first soft landing on the Moon's surface. (Russia)
1968 Apollo 8, carrying Frank Borman, James Lovell and
William Anders, was the first to orbit the Moon see the dark side . (US)
1969 Neil Armstrong and Buzz Aldrin become the first men to walk on the surface of the Moon. (US)
1972 Pioneer 10, destination Jupiter,  was launched (US)
1974 Mariner 10 sends photos of Venus and Mercury back to Earth (US)
1977 The first of Uranus' rings are photographed by Voyager 2 (US)
1980 Voyager 1 passes Saturn and sends back photos of Saturn's rings. (US)
1986 The Space Shuttle Challenger explodes 73 seconds after its launch. (US)
1994 The Shoemaker-Levy comet crashes into Jupiter
1996 Yuji Hyakutake makes the first sighting of Comet Hyakutake (C/1996 B2). (Japan)
1997 The spacecraft Cassini is launched towards Saturn (US)
1998 The International Space Station construction begins.
1999 The real Hubble Constant, the speed at which the universe is expanding, is calculated. (US)
1999 The Mars Polar Lander is lost at the south pole of the planet.  (US)





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1958 The first US satellite, Explorer I, is launched. It identifies the Van Allen radiation belt in the Earth's magnetosphere.
1961 Vostok I is the first spaceship to carry a man into space. The cosmonaut's name is Yuri Gagarin. (Russia)

1963 Valentina Tereshkova, the first woman in space, made 48 orbits of the Earth in the Vostok 6 spaceship (Russia)

1966 Surveyor 1 makes a soft landing in the Ocean of Storms, on the Moon's surface (US)

1970 The Venera 7 spacecraft becomes the first man-made object to return information to the Earth, after a soft landing on Venus. (Russia)

1976 Viking 1 and Viking 2 make soft landings on Mars (US)

1978 James Christy and Robert Harrington discover Pluto's moon, Charon. (US)

1986 Voyager 2 reaches Uranus. (US)
1990 The space shuttle Discovery puts the Hubble telescope into orbit. (US)
1995 The Galileo space probe reaches Jupiter's atmosphere (US)
1997 Pathfinder lands on Ares Vallis, Mars (US)
1998 The Lunar Prospector maps the surface of the Moon from a distance of 100 kilometres. (US)
1998 The Galileo spacecraft helps scientists to discover the origins of Jupiter's rings (US)
1999 The space shuttle Columbia, piloted by Col. Eileen Collins, puts the Chandra X-Ray Observatory into orbit. (US)
2000 The space shuttle Endeavor set out on its radar topography mission of the Earth. (US)
2001 Evidence that water existed on the surface of Mars comes from the study of the Shergotty meteorite.  (US)
2004 The spacecraft Cassini arrives at Saturn (US)
2005 The European Space Agency probe, Huygens, launched from the spacecraft Cassini,  lands on Titan (US/EU)





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2000 The NEAR Shoemaker spacecraft sends back images of the asteroid Eros (US)

2001 The Mir Space Station, after 15 years in orbit, is crashed into the South Pacific Ocean.

2004 Mars Expedition Rovers "Spirit" and "Opportunity" landed on Mars and started sending back images and information about the surface rock. (US)

2006 Launch of the New Horizon's spacecraft to Pluto and beyond.

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