Some YECs believe that the term 'ha-shamayim' (vs. 1, 9, etc.) in Genesis 1 is just a way of saying 'shamayim' (v. 8 only, and Gen 2:4b). So they claim that the phrase 'in the raqia ha-shamayim' regarding the luminaries is just an equation reminding the reader or hearer that 'God called the raqia “shamayim”' (v. 8).
But, in the account, it is self-evident that the 'ha-' prefix used for 'ha-erets' is not referring to the same exact thing as it refers to by 'erets' without the prefix. In fact, in Genesis 1 and 2 combined, there are at least five distinct words each of which strictly refers to a distinct thing regarding the general idea of 'that which is underfoot'. There is one term for 'dust' or particles ('apar', Gen 2:7); another term is for such things as land regions and land-versus seas ('erets'); another term is for dirt as a kind or range of thing ('adama' and 'ha-adama'); there is another term specifically for 'dry ground' as opposed to submerged by water ('yabbashah'); and there is a term specifically for 'the entire Earth', as in planet Earth ('ha-erets').
The account makes little sense in all these terms if we ignore them all and reduce them to one undifferentiated word, such as 'earth', and let the context alone help us determine which exact thing is meant in each instance. So it makes even less sense to 'conceptually' so reduce them, since the account uses all of them. Are they all just different words for the same exact thing? If that is so, then the account is therein engaging in a nearly-useless kind of variety---as if the account would be boring without it. But, if that is the case, then the account is too much like a simplistic Fairy Tale, only one that uses a nearly useless variety of words for the same exact thing. But it self-evidently does not so use this variety of terms for things 'underfoot'. This is self evident to anyone who bothers to read the Hebrew text with its self-evidently different things in mind.
Also, Genesis 2:4a uses only 'ha-shamayim' and 'ha-erets, while 2:4b uses only 'shamayim' and 'erets'. It would be useless if this were a parallelism of near or exact equivalence, and not a parallelism of relationality between distinct things. Parallels of relationality between distinct things are such as 'man and husband'; 'husband and wife'; 'planet and land masses'; 'general sky and special, atmospheric sky'.
Indeed, Genesis 1 is overall about the planet and the cosmos, and Genesis 2 about only the land mass on which humans abide. So the idea of parallelism of relationality between distinct things makes the far better sense of Genesis 2:4 than does parallelism of near or exact equivalence. In other words, this verse thereby best affirms, and distinguishes between, Genesis 1 and 2. In fact, in this way, the reader or hearer is given to expect that Genesis 2 is about only that---and is not, as many skeptics claim, an unexpectedly alternate and contrary account of how God created everything.
So it would be odd, to say the least, if the referent in Genesis 1 for 'ha-shamayim' and 'shamayim' were exactly the same. It especially would be odd if it were either the physical spatial dimension or a merely generalistic 'sky'; or, depending purely on 'context', if it were the luminary realm as distinct from that where the weather happens, or vice versa. This is because of something that Faulkner reasons on the account: God, on the one hand,
(A) would
not have burdened the ancient Hebrews with a concept to which they supposedly cannot have related, the geometrically cosmic thinness of Earth's breathable air,
and, on the other hand,
(B)
did exactly that for some entirely non-intuitive and esoteric physical cosmological object (an effective shell of water surrounding the total body of stars and galaxies).
This is a most stark double standard. It also does so by invoking the lesser value (mere physical constituency) at the expense of the greater value (Divine Design, even of that same constituency). One could be forgiven for thinking that Faulkner* would be happy if Genesis 1 were entirely about 'cosmic physics', that is, so that the Bible contained
no account of the creation of the Earth's ecology.
*Faulkner, D. (2016). Thoughts on the
rāqîa‘ and a Possible Explanation for the Cosmic Microwave Background.
Answers Research Journal 9 (2016):57-65.
https://assets.answersingenesis.org/doc/articles/pdf-versions/arj/v9/raqia-cosmic-microwave-background.pdf (
https://answersingenesis.org/astron...ible-explanation-cosmic-microwave-background/)