The moon, stars, and sun are created to be used as markers of time once creation is complete.
And Elohim said, “Let there be lights in the expanse of the skies distributed between the night and the day. And they will serve as signs and for seasons, and for days and for years. And they will serve as lights in the expanse of the skies shining on the earth. And it was so
This verse, a command by God to bring the lights of the heavens into existence, as in verse 1:3, stands in sharp contrast to the cosmologies of the cultures surrounding the Hebrews. As has been discussed earlier, and will be continually demonstrated, Genesis 1 is, in part, a polemic against those cosmologies in which gods are part of nature or in which nature’s entities (sun, moon, stars, lights, wind, sea, air, etc.,) are seen as divine. In this story, God reveals to us that nature is mundane and, as we shall see below, is to be governed by mankind, not the other way around!
Let there be lights: At this point in the creation week, the sources of light have yet to be created. This presented no problem to the ancient readers of this verse. As many commentaries[ref]An excellent enumeration of these commentaries can be found in Wenham, Gordon J., “Word biblical Commentary: Genesis 1:15”, p 22[/ref] demonstrate, the cosmology of the ancient Hebrews did not require the sun, moon, and stars to be present for light to exist. They knew that during even the darkest and cloudiest of nights, light was still manifest. Hence, while they knew light was closely associated with its sources, their world-view did not require their existance.
distributed between the night and the day: The Hebrew verb for divide or separate is here used in its hiphil infinitive construct form, הַבְדִּיל (havdil). Written literally the lights are commanded “to divide themselves between the night and between the day.” Note carefully that, as was discussed in the commentary of the first day, it is the spatial representation of light and dark that is in view.
And they will serve as lights: לִמְאוֹרֹת בִּרְקִיעַ (limorot birqia), the first three Hebrew words of 1:15, is almost always translated as “let them be for lights” or “let them serve as lights”. However, the use of “let” is misleading. In previous verses the verb actions expressed by “let them…” were translated from an imperative Hebrew verb form – usually the jussive. In this verse, the verb, וְהָיוּ (vəhayu) is not expressed in an imperative form. In other words, 1:15 is a statement of purpose or rationale, not creation.
And Elohim made two great luminaries – the great luminary for ruling the day and the small luminary and the stars for ruling the night. 17 And Elohim set them in the expanse of the skies to shine on the earth 18 and to rule over the day and the night [as well as] to separate the light from the dark.And Elohim regarded it as good.
Two great luminaries: The sun and moon respectively.
for ruling: taken from the Hebrew word, לְמֶמְשֶׁלֶת (ləmemshelet), the word literally means for-the-rule-of and derives from the root verb, מָשַׁל (mashal). Mashal connotes ruling as in “the king ruled”, but the precise meaning what it means to ‘rule’ in the mashal sense is uncertain. In most cases mashal is viewed as the exercise of regal authority for the benefit of those who are ruled, rather than demanding or requiring obedience. Thus, we see in 1:16, the regal authority of the two lights is to be exercised for the benefit of the earth and, presumably, its vegetation – if only because light is expressed everywhere in the Bible as beneficial[ref]In Genesis 3:16, the wife is commanded to return to her husband when in pain and he will mashal over her. This should be understood as responding to his wife’s distress – exactly what a benevolent ruler is ordained to do[/ref]. In verse 1:18 the semantics of mashal are repeated – a common Hebrew literary technique used for emphasis.
And there was evening and there was morning, a fourth day.