In celebration of the International Year of Astronomy in 2009, New Scientist takes you on an armchair tour of some of the most important telescopes ever built. For more information on these and other pioneering telescopes, read Eyes on the Skies: 400 Years of Telescopic Discovery by Govert Schilling and Lars Lindberg Christensen (Wiley-VCH, 2009).
Next Image 1 of 15 Galileo’s refractor (1609) The exact origin of the telescope is still controversial. The oldest existing documents attribute its invention to the Dutch spectacle maker Hans Lipperhey in the early 17th century. Lipperhey found that placing a convex lens at one end of a tube and a concave lens at the other allowed him to magnify distant objects. Though he didn’t invent the telescope, Galileo improved on its design – gradually increasing its magnification power. And he was the first to realise that it could be used to study the heavens rather than just to magnify objects on Earth. Here you can see Galileo demonstrating one of his telescopes to the ruler of Venice in August 1609 (Galileo is standing to the right of the telescope). In the years to come, Galileo’s observations – including the discovery of four large moons orbiting Jupiter – would lend credence to the sun-centred worldview of Nicolaus Copernicus, who removed the Earth from its central position in the universe. (Image: Science Photo Library: from Eyes on the Skies: 400 Years of Telescopic Discovery by Govert Schilling and Lars Lindberg Christensen)