Moon

The Moon is the only natural satellite of Earth.

Background
On July 16th, 1969, a team of the United States Air Force in a Virgo II lunar lander named Valiant 11 landed on the Moon, the first human beings to do so. On November 14th that year, a Virgo III lander named Valiant 12 landed on the Moon, and left the national flag of the United States on its surface before their departure.

In 2020, the Delta IX series of rockets were commissioned by the United States Space Administration, which underwent missions to the Moon, one of which was the 17-day Zeus 12. In 2052, the final manned mission to the Moon occurred, and during this, the flag left by the Valiant 12 was recovered and brought back to Earth, where it was put on display in Washington, D.C.'s Museum of Technology.

At an unknown point in history, a significant historical event occurred in the Mare Tranquillitatis (Sea of Tranquility) lunar mare.

The Boulder Dome experimented with constructing settlements on the Moon.

Appearances
While the moon appears in the skies of every game in the Fallout series, significant mentions of the Moon appear in Fallout 3, Fallout: New Vegas, Fallout 4, and Van Buren.