The Genesis account relates that during the fourth creative “day,” God caused luminaries to “come to be in the expanse of the heavens.” (Ge 1:14, 19) This does not indicate the coming into existence of light (Heb., ʼohr) itself, since this is shown to have existed previously. (Ge 1:3) Nor does it state that the sun, moon, and stars were created at this point. The initial verse of the Bible states: “In the beginning God created the heavens and the earth.” (Ge 1:1) Thus the heavens with their celestial bodies, including the sun, existed for an undetermined period of time prior to the processes and events stated as occurring during the six creative periods described in the following verses of the first chapter of Genesis.

Thus the record here states what the already existing sun, moon, and stars now became in relation to planet Earth. On the first “day” light (Heb., ʼohr) evidently gradually penetrated the cloud layers still enveloping the earth and would have become visible to an earthly observer, had he been present. (Ge 1:3) On the fourth “day” things changed. The statement that “God put them in the expanse of the heavens” on that day expresses the fact that God caused the sources of light (Heb., ma·ʼohrʹ), namely, the sun, moon, and stars, to become discernible in the expanse. Their purpose was to “make a division between the day and the night” and to “serve as signs and for seasons and for days and years.” In addition to being signs of God’s existence and majesty, by their movements such luminaries enable man to mark accurately the natural seasons, days, and years.​—Ge 1:14-18; Ps 74:16; 148:3.