(NASB) Genesis 1:1-5
1 In the beginning God created the heavens and the earth. 2 The earth was formless and void, and darkness was over the surface of the deep, and the Spirit of God was moving over the surface of the waters. 3 Then God said, “Let there be light”; and there was light. 4 God saw that the light was good; and God separated the light from the darkness. 5 God called the light day, and the darkness He called night. And there was evening and there was morning, one day.
I am going to refer to Classical Hebrew and the principles of hermeneutics to break down these five verses....
1 In the beginning God created the heavens and the earth.
Many people assume that this was part of day 1, but the Bible never makes that claim. The heavens and the earth were merely created "in the beginning," which could very well mean "in the beginning of time, during the Big Bang, etc." The earth, stars, planets and other astral bodies could have sat in a dark, lifeless, void for billions of years prior to the start of the creation of biological material (life). This is known as the Gap Theory.
2 The earth was formless and void, and darkness was over the surface of the deep, and the Spirit of God was moving over the surface of the waters.
The fact that it clearly states that the earth was formless and void, immediately makes me think of a gaseous state. Darkness being over the surface of the deep is obscure, but many think it refers to an ocean. You have to keep in mind that at this point, the earth couldn't have an ocean if it was formless and void. The surface of the deep could refer to the black, deepness of space. It is an unknown piece of data.
However, in later verses of Genesis, we learn that God created an expanse between the waters, thus separating them. The implication is "ground water" and "airborne water." The Spirit of God moving over the surface of the waters could be referring to God moving through the atmosphere (clouds or vapor dome), while the ground water could be some type of icy core (think comet/asteroid surrounded by gas).
3 Then God said, “Let there be light”; and there was light.
We must stop right here and take a side road for a moment. If you look at the Classical Hebrew, the word for light is "owr," but it does not mean an object that emits light. It literally means illumination, or enlightenment. Keep that in mind...
4 God saw that the light was good; and God separated the light from the darkness.
Again, the Classical Hebrew uses the word owr (illumination or enlightenment) followed by "choshek," which means darkness, but it refers to the opposite of owr; blindness, misery, ignorance.
Many believe the Bible is talking about daytime and nighttime. It's not. The Hebrew word for night is "layil," which is completely different than "choshek" (the absence of owr). Layil has not been used in the Hebrew yet, so it is not talking about a sun/moon cycle. They have yet to be created.
So what or who is emitting this owr (illumination)? God Himself and the creation of knowledge/wisdom. The choshek (absence of) is everything that is ungodly thus far. "Let there be light" refers to godly illumination or enlightenment.
5 God called the light day, and the darkness He called night. And there was evening and there was morning, one day.
The ancient Hebrews could have been talking about God creating during owr (illumination) and stopping at choshek (absence of illumination). Christian translations don't use the Talmud (oral teachings) so the exact nature of this verse is a X factor. It is worth noting that the Hebrew culture considered a day to be the time from sunrise to sunset. Nighttime was something completely different.
The Hebrew word for an object that emits light is "maor," with the plural being "maorot." On the 4th day of creation, the maorot are created (sun and moon). Notice that the words changed from "owr" and "choshek" to "maor and maorot" in the Classical Hebrew. This means that the first 5 verses in Genesis are NOT referring to light from a sun, star, moon etc. but literally the illumination/enlightenment from God vs. the absence of it. Prior to Genesis 1:14 (the creation of the sun/moon), the Hebrew words of maor and maorot were not used.