Let me talk about the most important thing first, then the less important thing about this question 2nd, and finally a very wonderful thing about this chapter at the end.
There are many small details about creation we are not told in the scripture, because they truly do not matter if we have faith. Our faith isn't reliant on believing or knowing that God made worms before antelope. That's not the basis for our hope or salvation.
Saving faith is only faith in Christ, risen, and is built by hearing the Word of Christ (in the 4 gospels), Romans 10:17 tells us. Faith
isn't based (correctly!) on believing this or that theory about creation, theory B instead of theory J. We are told that the only good foundation for faith, the only, is hearing and doing the Words of Christ -- Matthew 7:24-27.
No other foundation is safe, over time.
All other foundations will fail.
Unless a person is hearing and doing as Christ said, they will not make it.
If we do hear His words, and do them, then we can be totally assured with absolute certainty that we will make it, safe and sound on the rock of hearing and doing His words.
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Ok, the small detail about the light on the first day in Genesis, and then the sun, moon and stars revealed on the 4th day. Since the first day has a normal morning and evening, it seems to be a day like the other days, instead of the theory people came up with that somehow the days before day 4 are unlike those after day 4. So, we can guess (all views involve some assumptions or guesses, even if the person does not realize it!), that the light might be the sun, beginning to shine, on the already rotating all-ocean surface ("formless") Earth, and that would mean that the 4th day sun, moon and stars becoming visible (in this vision or revelation) means that they were not visible in the prior days, but
the message is the same message that is repeated 7 times to us in the chapter -- the sun, moon and stars are part of all that is "good", helpful, pleasant, useful, delightful, wonderful, for us, as our home!
We have a wonderful home God has made for us, and it is "very good". Hallelujah.
14 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.
Notice that only some words of actual speaking from God are given -- those in quotation marks here. Just like the vision to Peter in Acts chapter 10 -- only some words are given, just enough to eventually understand the essential meaning...
if a person truly listens. Peter did not understand at first, right off. He didn't understand. But later, he would eventually understand. There were just enough words in the vision to get to the only, essential meaning. The meaning being given Peter was
not to merely go hunting for supper or such! (even though those were indeed the words...they were
not the meaning).
Moses is getting (we assume it is Moses given this vision or revelation) a sense of key meaning, and even some brief words/narration (but not much!) from God. The essential meaning is very clearly said though:
"it was good" -- good for whom? good for us, as our home -- we can notice, once we have had time to realize He has said this 7 times, and consider what He has made.
Notice that while we are told God created the sun, moon and stars -- as all believe that believe He is the creator of all that is....
....we are not actually told when here. Because that is a relatively trivial detail, really. Consider: would it matter if it was a certain number, X amount of time -- for an Eternal God of all the Universe? Not really, of course. Time duration is no kind of problem for Him.
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Now for the truly wonderful thing this chapter can do for you.
Consider: we know first God chose not to reveal things that ultimately don't matter. The vision/revelation does have a purpose -- it can
change you.
If we truly listen, with our heart/soul/mind, listening, to the words, without an agenda, and with faith. It can/will alter our minds. Lift us up out of worldly thinking and concerns. That's the primary effect of this chapter on us, if we let it happen. By laying aside all of the ideas/debates/doctrines, and just
hearing.
Everyone should take the time to set aside every doctrine and agenda and be truly listening, with all of their being, and just affected by the wonder and glory of it. It's an blessing of rare quality, so much better than just some good weather or nice food or such.