Moon

The is a planetary body floating above the world, and is shown only at nighttime. The moon was created by the Sage of the Six Paths, through his Chibaku Tensei technique. He collected a massive amount of earth to seal the physical remains of the Ten-Tailed Beast after he sealed its chakra into his own body, and then launched the stone prison into space, thus creating the moon.

Madara Uchiha's ultimate plan, the Moon's Eye Plan, involves recreating the Ten-Tailed Beast through the other tailed beasts, become its jinchūriki, and then project his Sharingan onto the moon to cast his "Infinite Tsukuyomi": a worldwide-scale and perpetual genjutsu which will allow Madara control every living being on the planet, uniting them under him and creating a world with no war nor hatred, and making himself the ruler of the world.