Moon

The Moon is a natural satellite of Earth, and is the only one which has a stable orbit around the planet. It appears several times in the Godzilla series.

The Mysterians
After leaving the planet Mars, the Mysterians dock their Space Station on the dark side of the Moon while they launch plans to invade Earth.

Destroy All Monsters
In order to successfully take control of Earth's, the Kilaaks build a transmitter tower and a base on the Moon. The JSDF and UN launch an expedition force of humans aboard the Moonlight SY-3 to the Moon, and a battle rages which results in the Humans blowing up the base's entrance, forcing the Kilaaks inside to revert to their metallic forms, and the destruction of the Transmitter Tower, freeing the Kaiju from the alien race's grip.

Godzilla vs. Redmoon
In this unreleased film, the titular antagonist Redmoon lives on the Moon, and comes to Earth to invade. He meets up with Erabus, who also normally lives on the Moon.

Godzilla vs. Hedorah
In the English dub's main song, Save The Earth, it is mentioned in the Lyrics that if the Humans don't stop polluting Earth, the only option may be 'movin' to the Moon'.