Is the Sky a Solid Vault?
Job 37:18 speaks of God “spreading out the skies, hard as a mirror of cast bronze.” Incidentally, Genesis 1:17 also refers to “the vault of the sky.” A vault can be defined as an arched structure forming a ceiling or roof over a wholly or partially enclosed construction. I believe that this is an apt description of the sky forming an arch above the earth.
Concerning being “hard as a mirror,” this passage reminds me of my first job as a software engineer, and my training in celestial mechanics. I helped program the onboard computers for the first Space Shuttle mission in 1981. My programs included flight control during all three phases of the mission: ascent (liftoff), orbit, and descent (re-entry). The re-entry into the atmosphere comes to mind here. When re-entering the atmosphere from space, the attitude and acceleration of the Shuttle must be precise; otherwise, the Shuttle could literally “bounce” off the atmosphere (or it could burn up). In this respect, this barrier between our atmosphere and space could indeed be described as being “hard as a mirror.” Perhaps the Bible was speaking of truths not discovered by science for another 4,000 years or so.
Also, by definition, the sky is indeed a vault. Genesis 1:8 says, “God called the vault ‘sky.'”