Galileo's drawings of Jupiter's satellites, 1610.
© Science Museum / Science & Society Picture Library
Page taken from the book, 'Sidereus Nuncius'(The Sidereal Mesenger) written by Galileo (1564-1642) and published in Venice in 1610. This short work made Galileo a celebrity overnight, as it was the first written account of what could be seen in the heavens with the newly invented telescope. Using a telescope of his own design, Galileo observed that the planet Jupiter had four stars, that like our Moon went around the planet in a predictable manner. He named these new moons the 'Medicean Stars' after his patron the Grand Duke of Tuscany, Cosimo de Medici II. The daily movements of these satellites of Jupiter, now known as the Galilean Moons, are shown in sketches over several pages.