What was Pythagoras' contribution to astronomy?

Answer 1

Greek Astronomy was intrinsically linked to mathematics, and Greek astronomers sought to create geometrical models that could imitate the appearance of celestial motions. This tradition originates around the 6th century BC, with the followers of the mathematician Pythagoras. Pythagoras believed that everything was related to mathematics and that through mathematics everything could be predicted and measured in rhythmic patterns or cycles. He placed astronomy as one of the four mathematical arts, the others being arithmetic, geometry and music.

Whilst perhaps best known for his theorem 'The square of the hypotenuse of a right-angled triangle is equal to the sum of the squares on the other two sides' or put a bit more simply, a2+b2=c2, Pythagoras did have some input into astronomy, albeit a bit esoteric by today's thinking. Pythagoras believed in the "harmony of the spheres.", that is that the planets and stars moved according to mathematical equations, which corresponded to musical notes and thus produced a symphony. This 'music' is not literally audible, but simply a harmonic or mathematical concept.

By the time of Pythagoras the five planets visible to the naked eye - Mercury, Venus, Mars, Jupiter and Saturn - had long been identified. The names of these planets were initially derived from Greek mythology before being given the equivalent Roman mythological names, which are the ones we still use today. The word 'planet' is a Greek term meaning 'wanderer', as these bodies move across the sky at different speeds to the stars, which appear fixed in the same positions. However, the picture is not so straightforward due to the orbit of Venus. For part of the year Venus appears in the eastern sky as an early morning object before disappearing and reappearing a few weeks later in the evening western sky. Early Greek astronomers thought this was two different bodies and assigned the names 'Phosphorus' and 'Hesperus' to the morning and evening apparitions respectively. Pythagoras is given credit for being the first to realize that these two bodies were in fact the same planet, a notion he arrived at through observation and geometrical calculations.

Pythagoras was also one of the first to think that the Earth was round, a theory that was finally proved around 330BC by Aristotle.