How different models of the universe have been generated over time By Sophai 500 BCE Pythagoras suggested that the Earth is a sphere. 300 BCE Aristarchus attempted to calculate the distance between the Earth and the Sun He guessed that the Sun is about 20 times further away than the Moon as well as 20 times larger. 240 BCE Eratosthenes was the first person to measure the Earth's circumference and tilt. 230 BCE Aristarchus of Samos suggests that the Earth revolves around the Sun 1572 Tycho Brahe dissproved Aristotle’s theory of an unchanging universe when he disscovered a new star. 1610 The first telescopes are independently invented by Hans Lippershey, Zacharias Janssen and Jacob Metius. Galileo Galilei was one of the first people to use the telescope as an astronomical instrument. 1619 Johannes Kepler worked out the relative speeds and distances of the planets. 1633 Galileo's theory of relativity shows why we can't feel the Earth move. 1655 Saturn's moon Titan is discovered by Christiaan Huygens. 1725 James Bradley observes stellar aberration. 1785 William Herschel creates one of the first maps of the Milky Way. 1792 William Herschel discovers Uranus. 1846 Johann Galle discovers Neptune. 1926 Hubble became the first person to categorise galaxies according to their appearance. 1930 Fritz Zwicky predicts the existence of dark matter. 1997 The Hubble Space Telescope shows that most galaxies have supermassive black holes at their centre.