Paul writes about a man (himself?) who ". . . was caught up to the third heaven" (2 Corinthians 12:2b), which explains why the Hebrew word for "heaven" is plural. Perhaps a good understanding would be that the birds fly in the first heaven, the starry universe beyond our atmosphere is the second heaven, and the third heaven is where God's throne is located where we will join Him in the future. At least two Bibles (NIV, NLB) translate shamayim as "sky," but the majority of translators prefer "heaven" or "heavens."
The third heaven is not accessible to us now by space probes or telescopes; only after the resurrection or by temporary special revelation is human access possible. While living, we are confined to our four-dimensional physical universe of space and time. Yet, God and the angels can step into our universe at will as if they were from a spiritual dimension that is adjacent to and very near ours.
Day 2, Words, Heavens, Stretched, Atmosphere, Magnetic, Ending