^ rāqîaʿ
"...the firmament is the vast solid dome created by God on the second day to divide the primal sea (called tehom) into upper and lower portions so that the dry land could appear..." --
https://en.wikipedia.org/wiki/FirmamentPossibly the most solid thing in the universe is the dome. The dome is, essentially, empty space. It reaches throughout all material into the emptiness where material barely exists. It is many light-years "high," and contains all material things, flowing through them.
This is what is said in Genesis chapter 1, especially verses 6 thru 9. How do we know that Genesis says this, even though Genesis doesn't talk about light-years? Because we have found that it is light-years in fact. So, that is what Genesis is saying.

Says who because that is not what is written.?
KJV
Gen 7 And God made the firmament and divided the waters which were under the firmament from the waters which were above the firmament and it was so
Gen 8 And god called the firmament Heaven and the evening and the morning were the second day.
Gen 9 And God said, Let the waters under the heaven be gathered together unto one place, and let the dry land appear: and it was so.
So your saying Heaven is light years high?