Rána

When the Valar first set the Moon and Sun in the sky, their intention was for the new lights to follow an ordered passage over Arda. Each was to travel from West to East and return, with their lights mingling as they passed one another. Tilion, the steersman of the Moon, proved unreliable at following this path: drawn to the light of the Sun, he wandered too close and upset the purposes of the Valar. Though the Quenya name for the Moon was properly Isil, Tilion's wanderings caused it to become known as Rána, the 'Wayward', among the Noldor of Aman.

Because of the straying path of the Moon, and considering that the new brilliant lights left the stars hidden, Varda reconsidered her plans, and instead ordered things so that each would set in the West and pass beneath the world, re-emerging in the East to rise into the sky once again.