 Galileo Galilei was recently selected as a main motif for a high value collectors ' coin : the € 25 International Year of Astronomy commemorative coin , minted in 2009 . This coin also commemorates the 400th anniversary of the invention of Galileo 's telescope . The obverse shows a portion of his portrait and his telescope . The background shows one of his first drawings of the surface of the moon . In the silver ring other telescopes are depicted : the Isaac Newton Telescope , the observatory in <unk> Abbey , a modern telescope , a radio telescope and a space telescope . In 2009 , the <unk> was also released . This is a mass @-@ produced , low @-@ cost educational 2 @-@ inch ( 51 mm ) telescope with relatively high quality . 
