And God said, “Let there be lights in the vault of the sky to separate the day from the night, and let them serve as signs to mark sacred times, and days and years, ¹⁵ and let them be lights in the vault of the sky to give light on the earth.” And it was so. ¹⁶ God made two great lights—the greater light to govern the day and the lesser light to govern the night. He also made the stars. ¹⁷ God set them in the vault of the sky to give light on the earth, ¹⁸ to govern the day and the night, and to separate light from darkness. And God saw that it was good. ¹⁹ And there was evening, and there was morning—the fourth day.
(Genesis 1:14-19 -- NIV)