There are many theories about the birth of our solar system. The Tidal Theory (or Chamberlain-Moulton Theory) suggests that a passing star pulled dust and debris from the forming Sun, leaving a string of debris that eventually formed the planets.
Discovered by James Christy in 1978, Pluto's moon is named Charon. With a diameter of 1,172 kilometers (728 miles), Charon is just under half the size of Pluto. Due to this very small difference in size, some scientists consider Pluto and Charon to be a double (dwarf) planet.
The Apollo program was a manned U.S. space program that eventually put 12 men on the Moon. The first Apollo mission to circle the Moon was Apollo 8, and the first to land was Apollo 11. Apollo 13 never landed because of an accident en route that required the spacecraft to return to Earth after swinging around the far side of the Moon. The last Apollo mission to land on the Moon was Apollo 17.