Gen 1:14-19
14 God spoke: "Lights! Come out! Shine in Heaven's sky! Separate Day from Night. Mark seasons and days and years, 15 Lights in Heaven's sky to give light to Earth." And there it was. 16 God made two big lights, the larger to take charge of Day, The smaller to be in charge of Night; and he made the stars. 17 God placed them in the heavenly sky to light up Earth 18 And oversee Day and Night, to separate light and dark. God saw that it was good. 19 It was evening, it was morning — Day Four.

God spoke and creation happened.