"Firmament" was not a word in the original language. It was one that came into use from the days in which that was still a pre-astronomical idea. The best that can be said is that God created the heavens, which is still correct. And, insofar as we as human beings are concerned, the Earth is immovable.

All the discoverers of astronomic science were Christians, so get with the program. This is what God meant us to understand.