Spain is set to inaugurate a huge telescope on the Canary Islands, billed as the world's biggest scope for visible and infrared light and set to give astronomers a vital tool to map the universe.

Scientists behind the Great Canary Telescope say it is as powerful as four million human eyes combined and will allow researchers to peer into the darkest and most distant corners of space.

The observatory, perched on a mountain on the island of La Palma, will help astronomers with a wide range of research, from discovering new planets, to exploring galaxies and analysing black holes.

The telescope, which cost more than €100 million to build, was inaugurated by Spain's King Juan Carlos.

Its 36 separate pieces form a huge circular mirror which collects light on a surface almost 82 square metres in size, according to the scope's developer, the Institute of Astrophysics of the Canaries .

The IAC says is it is the largest device of its kind in the world and is bigger than the American Keck observatory in Hawaii and the four European VLT telescopes in Chile.

Researchers involved in the project believe the device will help "to discover things that are yet to be discovered" and "produce comparable images to those made by space telescopes, but of better quality as the GTC is bigger".