Creationists like to compare the First Act of Creation -- "Let there be light!" -- to the scientific theories of the Big Bang. It lets them have a warm feeling that somehow Science endorses their beliefs.
However, they stop short of considering the scientific view of the Second Act of Creation, namely, the Firmament: Genesis 1:6-8 "And God said, Let there be a firmament in the midst of the waters, and let it divide the waters from the waters. 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. And God called the firmament Heaven."
Unlike issues like the age of the universe, which depend on articulate interpretation of the text, the Firmament is described in the Biblical text precisely: it is a firm and clear surface, which separates the water above the land from the water below it. It's a rather nice explanation of why the sky is blue, and also where rain water is coming from. (The Hebrew word for heaven or sky is "Shamayim", meaning literally "water over there").
Actually, as far as science goes, this is a rather good scientific theory: it provides an explanation to natural phenomena, and is amenable to being tested by scientific methods. The experiment which may prove or refute it is rather simple: go up in the air until either you bump into the Firmament, or else reach above all atmospheric water, to where the sky is no longer blue.
Well, by the early 20th century such experiments were carried out, with the latter result (as was strongly suspected for a few centuries before that). The Firmament was put to rest, never to be considered seriously again -- strangely enough, not even by Creationists.
So, the next time you find yourself tied up in a silly argument with Creationists who insists on literal interpretation of the Bible, just ask them quietly, "By the way, whatever has happened to the Firmament?"...
