Galileo's observations of the Moon, 1610.
© Science Museum / Science & Society Picture Library
Pages from 'Sidereus, nuncius magna' (known as 'The Starry Mesenger', Venice, 1610) by Galileo Galilei (1564-1642), a book of astronomical theory and observations. Galileo was an Italian astronomer and physicist and outstanding representative of the movement which transformed medieval natural philosophy into modern science. Regarded as one of the greatest scientists of all time, Galileo discovered Jupiter's moons and the laws governing falling bodies. The illustrations on the pages show observations of the Moon made through a telescope. Although Galileo was not the inventor of the telescope, he was the first to use it succesfully for astronomical observation. His observations showed that the Moon had mountains and valleys and was not perfectly smooth and spherical as had previously been asumed.