A huge new observatory, called the Great Canary Telescope, is set to open its eye to the sky on Friday. With a main mirror 10.4 metres across, it will effectively be the largest telescope for visible and infrared light in the world. The next largest are the twin Keck telescopes on Mauna Kea, Hawaii, US, which have main mirrors 10 metres across. The Hobby-Eberly Telescope near Fort Davis, Texas, US, and South African Large Telescope (SALT) near Sutherland, South Africa both have main mirrors 11.1 by 9.8 metres across, but because of the way they are constructed, only a patch 9.2 metres across can be used at any given time for observations.
World’s largest optical telescope to see first light