Aristole describes the geocentric model of the universe
200 BCE
Aristarchus proposes a heliocentric model of the universe that is widely ignored
150 BCE
Ptolemy refines the geocentric model of the universe to try to explain the retrograde motion of the planets
1520
Ferdinand Mageilan is the first European to observe the Magellanic Clouds, which are later recognised as galazies outside the Milky way
1543
Nicholas Copernicus publishes a paper that presens the heliocentric model of the universe with a number of improvements on Aristarchus version
Giordano Bruno is burnt at the stake. One of his crimes was promoting the heliocentric model of the universe
kepler publishes Astronomia Nova, explaining the motion of the planets by using a heliocenntrc model of the universe and elliptical orbits
Galileo Galilei observes the moons of Jupiter
Galileo publishes his Dialouge on Two world systems, which argues in favour of the heliocentric model of the universe
Isaac Newton publishes Princupia Mathematica in which, among other things, he explains thE LAW OF UNIVERSAL GRAVITATION
THOMAS WRIGHT SUGGESTS THAT THE milky way galaxy is a flattened disk of stars and that nebulae might be other galaxies
Wiliiam Herschel discovers Uranus, the first planet not visible to the naked eye to be discovered
William Herschel constructs the first map of the milky way galaxy
Friedrich Bassel observes stellar parallax- the apparent movement of starsdue to Earth's movement around the Sun.
John Couch Adams discovers Neptune.
Ernst Opik demonstrates that the Andromeda nebula lies outside the Milky Way galaxy.
Georges Lemaitre proposes the Big Bang theory, which suggests that the universe began as a giant explosion of energy.
Edwin Hubble discovers evidence of an expanding universe, which supports the Big Bang model.
Clyde Tombaugh discovers Pluto.
Arno Penzias and Robert Wilson discover cosmic microwave background radiation, further evidence supporting the Big Bang model.
Neil Armstrong and Buzz Aldrin are the first human beings to walk on the surface of the Moon.
Pioneer 10 becomes the first spacecraft to leave the solar system. The spacecraft Galileo returns data suggesting that Europa has liquid oceans under its icy surface.
The spacecraft Galileo returns data suggesting that Europa has liquid oceans under its icy surface.
Planet-sized objects Eris, Haumea and Makemake are discovered in the Kuiper Belt
The international Astronomical Union rules that Pluto is not a planet