Question: In Genesis 1:8 God calls the expanse that separated the waters that were above and the waters that were below heaven. What is the relation, if there is one, to the heaven that we now think of with streets of gold and angels praising God? Is this expanse the only thing that God reveals as heaven in the OT, and then he reveals a new heaven in the NT? Can we call the expanse heaven today?
Answer: The word heaven/heavens is used to speak in some cases of our atmosphere as in Genesis 1:8. It is also used of the heavens which we would understand as outer space where the sun, moon, planets and stars are located. And it is used to speak of the abode of God. When reading a passage you need to ask which heaven is intended - the context will often be clear.