[BruceQW]

The Great Canary Telescope is the
largest optical telescope in the world
(Image: GTC)

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.
The Great Canary Telescope (GCT) cost $180 million to construct. Most of the money for GCT comes from the Spanish government, with additional funds from Mexico and the University of Florida, US.

The new telescope is set to begin test observations on Friday, with science observations intended to begin in about a year.
The observatory sits atop a mountain on the island of La Palma, part of the Canary Islands. It will make use of adaptive optics, in which shape-changing mirrors compensate for the distortion of light by the atmosphere.

The GCT's large light-gathering area will allow it to excel at studying faint objects, such as infant galaxies in the early universe. It will also study planets around other stars and black holes. Source