In reading the creation record of Gen 1 we must remember several things:
- It is written from a phenomenological point of view - what an observer would simply see. It is NOT a scientific nor astronomical record. This is reinforced with passages like Eccl 1:5 about the sun and moon rising and setting and hurrying back again.
- It concerns events on and around the earth only including the "firmament" of the sky. Nothing more.
- Hebrew has perfectly good words for "sun" (שֶׁמֶשׁ shemesh) and "moon" (יָרֵחַ yareach) that the author obviously goes to some trouble to avoid using.
- The fact that the sun produces its own light and the moon is a reflector of light is quite irreverent to the record of Gen 1 because all that matters is that they are both sources of light. The stars are also sources of light as also recorded elsewhere, such as Eze 32:7, Jer 31:35, etc.
- One of the several functions of the Gen 1 record is as type of salvation. God takes a world that (Gen 1:2) "tohu and bohu and hosek" = formless and void and dark; and by the end of the record we have, (v31) "And God looked upon all that He had made, and indeed, it was very good." That is we have the opposite - form, value and brightness!
- It is not necessary for the author of a bible passage to fully understand what is being revealed. We see this spectacularly in passages like Dan 8:27 and others. Thus, it is possible that the author was inspired to write the passage in the style and vocabulary they did to avoid misconceptions and unfounded claims.
- The "vault" or "firmament" (רָקִיעַ raqia) is called heavens (שָׁמַיִם shamayim) Gen 1:8 and represents the space between the waters below and water above.
- The Bible writers of Gen 1 makes no attempt to distinguish between what we now call the atmosphere and outer space beyond the atmosphere - they had no language nor understanding of these things and it did not matter to them. Heaven was anything above the earth or soil (where crops were grown). Birds flew in the heaven (Gen 1:20, 26, 28, 30, 2:19, 20, 6:7, etc); water came from above the heavens (Gen 1:6, 7, 7:11, 8:2, etc); the sun, moon and stars existed in the heavens (Gen 1:14), etc.
- Similarly, there is no concept of "planet earth" in Gen 1 - it is entirely foreign to the entire Bible. "earth" (אֶרֶץ erits) is simply dry, arable land (Gen 1:10).
- It is very significant that in the creation record of Gen 1 -
- The heavens are created on day #2 (Gen 1:8)
- The earth is created in day #3 (Gen 1:10)
Now, finally to the question at hand - it has been said that because many of the ancients worshiped the sun and moon, that the author of Gen 1 did not want to dignify the sun and moon by explicitly naming them but obliquely refers to them as "lights in the heavens"; and even more significantly that YHWH is the one responsible for their existence, and creation.
Thus, YHWH is greater than all the false gods of the heathen, especially the sun and moon. There are more complex theological reasons for all this but they do not matter here. The fact remains that God is responsible for all things.
It is also useful to recall that during the creation of the earth, other existing life-forms observed and cheered what was happening (Job 38:4-7).