(Click here to see the image
without text.)
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.