Mauna Kea, Hawaii hosts several telescopes. The most powerful is the W. M. Keck Observatory. Keck has 2 telescopes and both have mirrors which are 10 metres wide.
The moving parts of each telescope have a mass of 270 tonnes. Each of the 10 m main mirrors are made up of 36 hexagonal pieces. These pieces fit together to work as a single mirror. The position of each mirror can be adjusted to an accuracy of 4 millionths of a millimetre. A system called active optics makes these corrections two times a second.
Keck has produced images of objects in our Solar System which are almost as detailed as those made by space telescopes. Its tools have ensured the Keck observatory has remained one of the best in the world for almost 20 years.