Luna, in most cases called just "the Moon", by Earth's inhabitants, is the single natural satellite of planet Earth.
The Moon is a barren gray world with a very light atmospere. It is totally uninhabited by the time of the Xurian crisis.
The Moon is located inside the Terran star system.
Despite lacking faster-than-light capacity and modern Star League technology Earth is able to send manned missions in form of primitive rocket-spaceships to the Moon.