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, 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, then use the moon to cast his "Infinite Tsukuyomi" to create a world without war nor hatred, thus allowing him to rule it.