1971: Henry Kissinger secretly visits China to arrange visit for President Nixon, marking the beginning of an era of detente between the two countries. China is admitted into the United Nations.

Today: Although tensions remain, diplomatic relations between China and the United States have been largely normalized, and it appears likely that China will gain entry into the World Trade Organization.

1971: U.S. Apollo 14 and 15 crews become the third and fourth groups to explore the moon's surface. In the same year three Russian cosmonauts die when their Soyuz 11 capsule develops an air leak when reentering the earth's atmosphere.

1971: American astronomers discover two "new" galaxies adjacent to the earth's own galaxy, the Milky Way.

1972: The crew of Apollo 17 spends a record 75 hours on the moon's surface.

1998: The Lunar Prospector is launched. This is the first time in 25 years that NASA sent a probe to the Moon...