Kitt Peak National Observatory

Explanation: At the top of Kitt Peak Mountain near Tucson , Arizona lies one of the world's great collections of telescopes. As pictured , in the dome at the far left lies the 3.5-meter WIYN Telescope , famous recently for tracking distant supernovae. The next major dome to the right houses a 36-inch telescope now used mostly for imaging. Farther to the right beside a thin tower is a 2.1-meter Telescope used currently for imaging and spectroscopy. The unusual triangular building houses the McMath-Pierce Solar Telescope . In front of it lies the Vacuum Tower Telescope while in back are the Burrell-Schmidt Telescope and the SARA 0.9-meter automated telescope. At the far right lies one of the world's largest telescopes: the 4-meter Mayall Reflector . Kitt Peak recently celebrated its 40th year during which it helped establish the existence of dark matter and the first gravitational lens . Kitt Peak National Observatory is part of the United States' National Optical Astronomical Observatories and is operated under agreement with the National Science Foundation .