Cosmos – Carl Sagan Posted on 11th December 201212th April 2020 by Laurence I’ve started reading ‘Cosmos’ by Carl Sagan, this is a real classic book, written by one of the great astronomers of modern times. It is a very sad coincidence that as I was writing this I heard the news that Sir Patrick Moore had passed away, aged 89. What an inspiration he was to so many people. Dr Carl Sagan had an extraordinary ability to explain ideas, and make them comprehensible to everyone. He received an award for ‘distinguished contributions to the welfare of mankind’, and the Pullitzer Prize for literature. He sadly died in 1996. To the current and future generations, Professor Brian Cox may well one day be regarded in the same way. Carl Sagan’s ‘Cosmos’, front cover Even in the early pages of the book, before the end of the first chapter, I’ve been inspired to learn more. We haven’t even really got onto the astronomy yet. I’ve learnt a tantalising little bit about the ancient city of Alexandria, and some of the people who lived there and worked in its great library. The director of the library, Eratosthenes, correctly calculated the circumference of the Earth, over two thousand years ago. He did it by observing the shadow of vertical sticks at noon on June 21st in two different places. One, as he had read in a papyrus book in the library, had no shadow in Syene. The Sun was directly overhead. He decided to do the same test in Alexandria, and saw that the stick still had a shadow. He realised the only possible reason was that the Earth’s surface was curved. Eratosthenes hired a man to pace out the distance between Syene and Alexandria, 500 miles, and using this with the difference in the shadows, he correctly calculated the circumference to be 25,000 miles, accurate to just a few percent. Not a bad achievement for 2200 years ago. Not only this, I have already learnt that Alexandria was a place where all races lived in harmony, and marriages between them were encouraged. So by the end of chapter one, I need to find books to read about what life was like in Alexandria. And on to chapter two: ‘One Voice in the Cosmic Fugue’… Related posts
