Gen 1:6–8: raqia', "expanse"

Says God calls for a רָקִיעַ (raqia') between the waters (1:6), makes it (וַיַּעַשׂ אֱלֹהִים אֶת־הָרָקִיעַ, 1:7) with waters מִתַּחַת לָרָקִיעַ and מֵעַל לָרָקִיעַ, and names it שָׁמָיִם (1:8), the noun rendered "heavens" in 1:1. The lights are set בִּרְקִיעַ הַשָּׁמַיִם (1:14–17), and birds fly עַל־פְּנֵי רְקִיעַ הַשָּׁמָיִם (1:20; BSB "in the open expanse of the sky"). The BSB has "an expanse" and then "sky" for the thing and its name. The LXX has στερέωμα (note.language.Gen.1.6-Gen.1.28.lxx-stereoma-eikon).

Says BDB glosses the noun "extended surface, (solid) expanse" and describes "the vault of heaven, or ‘firmament,’ regarded by Hebrews as solid." It glosses the verb of the same root "beat, stamp, beat out, spread out"; in Job 37:18 that verb, תַּרְקִיעַ, is used of the skies, "spread out the skies, as strong as a mirror of bronze" (BSB).

Uncertain What physical picture the word commits the text to. No lean is taken here. (1) A solid vault, as BDB describes it. (2) The sky or atmosphere, with the waters above as clouds. (3) The language of appearance, with no commitment to a physical model. BDB's description is that lexicon's view, not a decision. Ancient pictures of the cosmos are discussed in note.historical.Gen.1.1-Gen.1.31.ane-cosmology; they do not fix the meaning.