TYCHO

conspicuous lunar crater constituting the centre of the most extensive system of bright rays (light-coloured surficial streaks) on the near side of the Moon. The crater's rays dominate the southern highlands and extend for vast distancesmore than 2,600 km (1,600 miles)across the Moon. The crater, located at 43 S and 11 W, measures 85 km (53 miles) in diameter and about 4 km (2.5 miles) deep. Because of its relatively young age, the crater is distinguished by hummocky rim deposits and seemingly fresh pools of dark flowlike materials. The U.S. lunar probe Surveyor 7, which landed on Tycho's northern flank in 1968, returned images of a very blocky rim and analyzed its aluminum-rich highland material.