November 25 - How big is the World? How we came to measure the Earth, Moon and Solar System.

 


In this talk, Alan Hunton will explain how ancient civilisations had little idea of the size of our Earth, nor how far it was from the Moon and other heavenly bodies. Greek philosophers and scientists working in Alexandria in Egypt during the first millennium BC began to unravel the puzzle and within a short period of time had discovered the size of the Earth and Moon and the distances between them. There was also a strong consensus that the Earth revolved around the Sun at this time. The invasion of Egypt by the Romans and the influence of
Aristotle stalled any further progress and it was not until the seventeenth century that Galileo and Kepler could determine distances to the Sun and the other planets using the earliest telescopes as aids. Finding the density of the Earth was solved by rambling in the Scottish highlands and careful measurements by Henry Cavendish.

 

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