I took an ancient Hebrew scriptures class. Lets see if I can paraphrase..
The words/phrases used for the firmament were the same used to refer to a crude slab of metal used for hammering into a shield. It was based on Egyptian concepts of the cosmos, not comparable to anything known in modern times.
http://skepticblog.org/wp-content/uploads/heaven_of_heavens.jpg
6And God said, Let there be a firmament in the midst of the waters, and let it divide the waters from the waters.
7And 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.
8And God called the firmament Heaven
OK, so there's rain water above
9And God said, Let the waters under the heaven be gathered together unto one place, and let the dry land appear: and it was so.
And one sea?
14And God said, Let there be lights in the firmament of the heaven to divide the day from the night; and let them be for signs, and for seasons, and for days, and years: 15And let them be for lights in the firmament of the heaven to give light upon the earth: and it was so.
16And God made two great lights; the greater light to rule the day, and the lesser light to rule the night: he made the stars also.
17And God set them in the firmament of the heaven to give light upon the earth,
The text seems to indicate there is only one firmament, and it has the name 'heaven'. Above it there is water, I don't see any evidence here the Bible speaks of a further heaven, though in an Epistle Paul speaks of having been taken up to the third heaven.
I guess it made sense in those days to speak of the water being above the stars so it didn't get in the way of seeing the stars. I might know more about Biblical astronomy if I'd gone to school in the deep South.
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