Keck: The Largest Optical Telescopes

Explanation: In buildings eight stories tall rest mirrors ten meters across that are slowly allowing humanity to map the universe. Alone, each is the world's largest optical telescope : Keck . Together, the twin Keck telescopes have the resolving power of a single telescope 90-meter in diameter, able to discern sources just milliarcseconds apart. Since opening in 1992 , the real power of Keck I (left) has been in its enormous light-gathering ability - allowing astronomers to study faint and distant objects in our Galaxy and the universe. Keck II, completed last year, and its twin are located on the dormant volcano Mauna Kea , Hawaii , USA . In the distance is Maui's volcano Haleakala . One reason Keck was built was because of the difficulty for astronomers to get funding for a smaller telescope.