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The Lunar Appenines (or Montes Apenninus in Latin) stretch for roughly 225 kilometers across the Lunar surface. One of its peaks, Mt. Hadley (where the Apollo 15 astronauts landed) climbs 14000 feet into the sky. The Apennines are bordered on one side by the smooth Mare Imbrium, an ancient, solidified volcanic plain 1300 miles in diameter. (Only part of it is visible here.) It formed when a huge asteroid impact some 4 billion years ago carved out a huge crater. The heat and shock created by the impact caused lava flows, which filled the crater and left the mountains around the rim. The craters Eratosthenes and Timocharis are 58 and 34 kilometers in diameter, respectively. Both of these impacts were made after the lava cooled. The small mountain-like feature inside the Eratosthenes crater (called the central peak) was caused by the shock of the impact. Archimedes (83 km), Autolycus (40 km), and Aristillus (55 km), were formed before the lava flow stopped altogether. You can see that only the rim of Archimedes is visible; the floor of the crater was filled by lava. The Z symbol between Archimedes and Autolycus is where Lunik 2, the first umanned spacecraft to reach the moon (and sent by the Russians), touched down on 9/12/59.