Like An Expanse - Ezekiel 1:22

Ezekiel 1:22 NASB

 Now over the heads of the living beings there was something like an expanse, like the awesome gleam of crystal, spread out over their heads.

God separated the waters above from the waters below when He created the universe.  God's view of creation below His throne is crystal clear, while our natural vision upward is limited to creation. We can only make out the sun, moon, and stars without the presence of His Spirit. 

That division between heaven and earth will disappear when the new creation is revealed.