Firmament: From the Vulgate firmamentum, which is used as the translation of the
Hebrew raki'a. This word means simply "expansion." It denotes the
space or expanse like an arch appearing immediately above us. They
who rendered raki'a by firmamentum regarded it as a solid body. The
language of Scripture is not scientific but popular, and hence we
read of the sun rising and setting, and also here the use of this
particular word. It is plain that it was used to denote solidity as
well as expansion. It formed a division between the waters above and
the waters below
(Genesis 1:7) The raki'a supported the upper reservoir
(Psalms 148:4) It was the support also of the heavenly bodies
(Genesis 1:14) and
is spoken of as having "windows" and "doors"
(Genesis 7:11; Isaiah 24:18)
(Malachi 3:10) through which the rain and snow might descend.