What is the firmament? Ancient cosmology in Genesis 1

The passages

And God said, Let there be a firmament in the midst of the waters, and let it divide the waters from the waters.

Genesis 1:6

And God made the firmament, and divided the waters which were under the firmament from the waters which were above the firmament: and it was so.

Genesis 1:7

In the six hundredth year of Noah's life, in the second month, the seventeenth day of the month, the same day were all the fountains of the great deep broken up, and the windows of heaven were opened.

Genesis 7:11

The problem

The Hebrew word raqia, rendered "firmament", comes from a verb meaning to beat out or hammer flat, as a metal plate. The Greek Septuagint translated it stereoma and the Latin Vulgate firmamentum, both meaning something solid. Genesis puts waters above it and has "windows of heaven" that open to let them down. Nothing like this exists. The sky is not a dome and there is no store of water above it. The picture matches Babylonian and Egyptian cosmology, where the heavens were a vault.

What believers and scholars say

Phenomenological language. The Bible, on this view, describes how the world looks to the eye. We still say the sun rises. The waters above can be understood as clouds, or as the upper atmosphere's moisture. Critics note that Genesis says the waters are above the lights in the sky, which does not suit clouds.

Accommodation. Many scholars, from Calvin onward, hold that God spoke through the cosmology of the original audience, without correcting it. Revelation was about who made the world, not how it works, and this is why the text does not need to be scientifically accurate. This view is common in Catholic and mainline circles and increasingly among evangelicals.

Functional reading. Walton argues that the focus is on what the heavens do, namely provide a space for life and weather, and not on what they are made of.

Critical view. Seely and others argue that the author really did believe in a solid vault, and that honest reading requires saying so.

Where this leaves it

Few modern readers think the sky is a hard dome. The disagreement is over what that means for how the text works. If the author shared the cosmology of his time, then the inspired message came inside an old picture of the world. Many believers can accept that. Others find it a reason to doubt the text's claim to a divine source.