I made these observations (from http://historical-jesus.info/djp1.html):Maybe the first heaven is the atmosphere, second is all of outer space, third is heaven.
>> In 2 Corinthians 12:2-3, Paul claimed to have gone to "third heaven"/"paradise" in order to meet Christ. "paradise" appears to be the equivalent of the heavenly Kingdom, where (good) Christians would join Christ in the future:
2 Corinthians 5:1 NIV "... we have a building from God, an eternal house in heaven ..."
Philippians 3:20a NKJV "But our citizenship is in heaven. ..."
1 Thessalonians 4:17 Darby "... and thus we shall be always with [the] Lord."
But where would Jesus reside in the heavens? Close to God, in the highest one:
Romans 8:34 Darby "... Christ who has died, but rather has been [also] raised up; who is also at the right hand of God ..."
Therefore, it is most likely a "three heavens" concept was adopted here.
What about the intermediate heaven, the second one?
That would be the starry firmament (with sun & moon), between the air and God's heaven, as defined in Genesis 1:14,15,17, 15:5, 22:17, 26:4; Exodus 32:13; Deuteronomy 4:19, 10:22, 28:62; 1 Chronicles 27:23; Nehemiah 9:23; Isaiah 13:10; Ezekiel 32:7; Matthew 24:29; Mark 13:25; Hebrews 11:12; Revelation 6:13, 12:1,4. (heaven='ouranos' in LXX and NT) <<
However I doubt that "third" in "third heaven" and "paradise (instead of "heaven") is not from an interpolator.
The first heaven is the air above earth (believed to extend all the way to the moon), the domain of clouds and flying birds.
Cordially, Bernard