The Gran Telescopio Canarias is also known as 'GranTeCan' or the 'GTC'. It sits 2,267 m up a mountain above the sea on La Palma. It is the largest telescope on the island. The GTC is owned by Spain, Mexico, and the University of Florida in the USA. It is looked after on the site by the local university, the IAC.

The telescope's mirror is 10.4 m across, making it the second largest in the world. It is made up of 36 hexagon-shaped pieces. These work together as 1 huge mirror. Computers carefully control all of the pieces to make sure that they line up perfectly. It took 7 years to build the telescope.

The GTC looks at visible and infra-red light. It has a special camera for each called OSIRIS (for visible light) and the CanariCam (for the infrared). The telescope can take images of objects millions of light years away within minutes. A smaller telescope with a 1 m mirror would need hours to produce the same.