Watch this video clip, from the world famous TV series "Cosmos" by Carl Sagan (the whole series is just fantastic and definitely worth watching even if it was made back in 1980!), about how the Greek astronomer Eratosthenes measured the circumference of the Earth around 200 BC. This is an excellent example of something that was discovered with only the very simplest of tools. There are many similar discoveries made in the past; can you think of examples?

Viimeksi muutettu: tiistaina 26. tammikuuta 2016, 17.08