A long exposure image shows sky rotation around the north celestial pole (marked by star Polaris), above moonlit landscape of Grand Canyon. The canyon Desert View watch tower is on the right and a fireball (bright meteor) is captured on the left. The Grand Canyon, a World Heritage Site in northern Arizona, USA, is the longest canyon on the Earth, a steep-sided gorge carved by the Colorado River steadily in about 17 million year time span. The canyon is 446 km long, ranges in width from about 6 to 29 km and attains a depth of more than 1.6 km (a mile).