Galilean telescopes, 1610.
© Science Museum / Science & Society Picture Library
These two telescopes are replicas of ones made by Galileo Galilei (1564-1642) after he learnt of the invention of the telescope in 1608. The longer refracting telescope magnifies only 14 times while the shorter one gives the greater magnification of 21. Both these telescopes give very restricted views so that Galileo was only able to view about a third of the Moon. However, despite these limitations, Galileo published 'Sidereus Nuncius' ('The Starry Mesenger') in 1610, which describes the celestial sights he saw with his new telescope. These included craters on the Moon, the phases of Venus and the moons of Jupiter. These facsimiles were made in 1923 at the Museo di Fisica e Storia Naturale, in Florence, Italy where the originals still reside.