The Bible starts out:
Genesis 1:1 In the beginning, God created the heaven and the earth.
Notice that "heaven" is singular here?
This is very important, because after all the creating is done, we read:
Genesis 2:1 Thus the heavens and the earth were finished, and all the host of them.
How is it "heaven" is singular in 1:1, and is plural in 2:1?
He must have created another "heaven" in between.
And indeed He did.
In fact, we know He created two more "heavens" in between, because Paul says:
2 Corinthians 12:2 I knew a man in Christ above fourteen years ago, ( whether in the body, I cannot tell; or whether out of the body, I cannot tell: God knoweth; ) such an one caught up to the third heaven.
Remember: this is the same Paul that warns us about making words plural that shouldn't be.
Galatians 3:16 Now to Abraham and his seed were the promises made. He saith not, And to seeds, as of many; but as of one, And to thy seed, which is Christ.
So now back to Genesis 1.
After God makes heaven and earth, He shears off a layer of water and balloons it out into space, calling the area in between (i.e., from the top of the ocean to the bottom of the water canopy) a "firmament".
Genesis 1:6 And God said, Let there be a firmament in the midst of the waters, and let it divide the waters from the waters.
Genesis 1:7 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.
He calls this firmament "Heaven" in the next verse.
Genesis 1:8 And God called the firmament Heaven. And the evening and the morning were the second day.
So now we have two "heavens" (or "firmaments"): the one created in Genesis 1:1, and the one created in Genesis 1:7.
I don't know when the third one was created; but we know it was, because Paul went there after he was beaten to death outside of Lystra (Acts 14).
So here's how it all stacks up:
- First Heaven = atmosphere = ground level to 62 miles up
- Second Heaven = outer space = 62 miles up to edge of universe
- Third Heaven = Heaven proper