§ Of the Sun and Moon and the Hiding of Valinor The Silmarillion

Because of the waywardness of Tilion, therefore, and yet more because of the prayers of Lórien and Estë, who said that sleep and rest had been banished from the Earth, and the stars were hidden, Varda changed her counsel, and allowed a time wherein the world should still have shadow and half-light. Anar rested therefore a while in Valinor, lying upon the cool bosom of the Outer Sea; and Evening, the time of the descent and resting of the Sun, was the hour of greatest light and joy in Aman. But soon the Sun was drawn down by the servants of Ulmo, and went then in haste under the Earth, and so came unseen to the east and there mounted the heaven again, lest night be over-long and evil walk under the Moon. But by Anar the waters of the Outer Sea were made hot and glowed with coloured fire, and Valinor had light for a while after the passing of Arien. Yet as she journeyed under the Earth and drew towards the east the glow faded and Valinor was dim, and the Valar mourned then most for the death of Laurelin. At dawn the shadows of the Mountains of Defence lay heavy on the Blessed Realm.