Ge 1:17, the expanse of the heavens immediately above the earth. The Hebrews seem to have viewed this as an immense crystalline dome, studded with stars, resting on the far distant horizon all around the spectator, and separating the waters above us from those on the earth. Through its windows the rain descended. It is not necessary to suppose they thought it was solid, Ps 19:1; Isa 40:22. It is not the aim of Scripture to give scientific statements of natural phenomena. Teaching religion, not astronomy of physics, it does not anticipate modern discoveries, but speaks of natural objects and occurrences in the common language of men everywhere. Hence, in part, its attractiveness in all ages as a book for the people.
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 (Ge 1:7). The raki'a supported the upper reservoir (Ps 148:4). It was the support also of the heavenly bodies (Ge 1:14), and is spoken of as having "windows" and "doors" (Ge 7:11; Isa 24:18; Mal 3:10) through which the rain and snow might descend.
Raqi'ah, "the expanse stretched out as a curtain" over the earth (Isa 40:22; Ps 104:2), resting on the mountains as its pillars (the language is phenomenal, as indeed necessarily is that of even men of science often): Job 26:11. It was the reservoir of rain and snow, which poured through its opened "windows" or "doors" (Ge 7:11; Isa 24:18; Ps 78:23). It includes the atmosphere immediately round the earth, in which the birds fly, and which bears up the clouds (Ge 1:6-7,20; in Ge 1:14 it also comprises the region in which the sun, moon, and stars are seen).
Firmament (from the Vulgate: firmamentum; Septuagint: stereooma) is derived from firmness; but the Hebrew expresses no such notion, as if Moses thought the sky a hard firm vault, in which the heavenly bodies were fixed. The sky in Job 37:18 is termed "strong, as a molten looking glass," namely, a polished copper mirror. But it is not the solidity, but the transparent clearness and the smiling brightness, which is the point of comparison. Otherwise, how could birds fly in a solid? The language is figurative and phenomenal. In Eze 1:26 the throne is seen above the "firmament," therefore the firmament must be transparent.
The Hebrew word is raqia, signifying 'expanse.' It is used for the celestial sphere that may be seen by looking upward, and also simply for the atmosphere in which the birds fly. We read that God called the firmament 'heaven:' this is 'heaven' in a broad sense as we read elsewhere of 'the stars of heaven,' but also of 'the birds of heaven.' Ge 1:6-20. The Psalmist speaks of them as distinct: "The heavens declare the glory of God; and the firmament showeth his handywork." Ps 19:1; 150:1. The living creatures in Ezek. 1 move amidst the firmament: "and the likeness of the firmament upon the heads of the living creature was as the colour of the terrible crystal, stretched forth over their heads above" (Eze 1:22), showing them to be executors of God's judicial government: cf. Eze 10:1.
In Scripture the word denotes an expanse, a wide extent; for such is the signification of the Hebrew word. The original, therefore, does not convey the sense of solidity, but of stretching, extension; the great arch of expanse over our heads, in which are placed the atmosphere and the clouds, and in which the stars appear to be placed, and are really seen. --Webster.
FIRMAMENT. It is said, Ge 1:7, that God made the firmament in the midst of the waters, to separate the inferior from the superior. The word used on this occasion properly signifies expansion, or something expanded. This expansion is properly the atmosphere, which encompasses the globe on all sides, and separates the water in the clouds from that on the earth.