The ‘authorized version’ of telescope discovery, is that Hans Lippershey, a German-born Dutch spectacle lens maker, filed a patent for two designs of what came to be known as the telescope in 1608. Spectacle lenses had been around for some time; Roger Bacon had written in 1262 about magnifying lenses, and a painting of Hugh of St Cher, 1352, shows him wearing spectacles.
Galileo heard about Lippershey’s patent, and recognizing the principle, made his own telescopes the following year, as did Simon Marius in Ansbach. But Robert Grosseteste, Bishop of Lincoln, 1175 – 1253, described in De Iride: “This part of optics … shows us how we may make things a very long distance off appear as if placed very close …” Somewhat later, Thomas Digges of Oxford, in 1571, wrote that his father was able: “by proportionall Glasses [to discover] things farre off …” It appears then that there is direct evidence of the use of telescopes in England 400 years before Galileo.
The earliest lenses known were excavated by Sir Arthur Evans in the Royal Palace of Knossos, dating to 1400 BC. Sir Austen Henry Lanyard found a 1.5 inch diameter crystal lens at Nimrud on the Tigris dating to 750 BC - currently in the British Museum. The Greek playwright Aristophanes, 424 BC, referred to a ‘lens’ in his play The Clouds, and Seneca the younger, 1st century AD, who was one time tutor to the Emperor Nero, wrote: “...[written] Letters, however small and indistinct, are seen enlarged and more clearly through a globe of glass filled with water…” The Islamic scientist, Hassan ibn al-Haytham, born in Basra, wrote a treatise on optics in 1021 in which he described the use of convex lenses to magnify images.
Sooner or later anyone messing around with lenses is likely to discover the telescope (or microscope) effect. If manufactured lenses have been around for at least 3,500 years, telescopes have probably been re-invented many times over.