The 4,200-meter-high summit of Mauna Kea, a dormant volcano, on the island of --------- hosts the world's largest astronomical observatory, with telescopes operated by astronomers from eleven countries. The combined power of Mauna Kea's telescopes is fifteen times greater than that of the Palomar telescope in California - for many years, the world's largest - and fifty times greater than that of the Hubble Space Telescope. Since astronomers observe the skies at night and car headlights interfere with observations, it is preferred that visitors drive to the summit area between sunrise and sunset. Daytime visitors are also welcomed.?