The Firmament (Hebrew: raqiaʿ, often translated "expanse," "vault," or "firmament").

Created on Day 2 (Genesis 1:6-8): Yah said, “Let there be a firmament in the midst of the waters, and let it divide the waters from the waters.” Yah made the firmament, divided the waters under it from those above it, and called it Heaven. The firmament functions as a separator or expanse in the created order—dividing earthly/ (lower waters) from upper waters. Birds fly “in the open firmament of heaven” (Genesis 1:20), showing the firmament includes the sky/atmosphere.

Later, celestial lights were placed in it (Genesis 1:14-17). The term raqiaʿ relates to something spread out or beaten/expanded (like metal in other contexts, e.g., Job 37:18), but in Genesis it emphasizes the visible sky/heavens as an ordered expanse.

Key characteristics: Structural/organizing element of the cosmos; not luminous itself; called “Heaven”; encompasses or contains the domain where lights move and birds fly. It declares Yah’s handiwork (Psalm 19:1).