The third heaven is the dome or firmament, which is a sea of glass. It's a rigid crystalline sphere on the edge of space which formed in response to the creation of gravity on the second day.
The Third Heaven
The Second Heaven
Most of the space between the firmament and Earth is the cosmos or observable universe. There's something very odd about the cosmos: there's a disconnect between what we can see vs. what we believe about it.
The First Heaven
Part of the space between the firmament and Earth is the area in contact with the Earth that we call the atmosphere, or sky. This is where the birds fly. It's referred to as the open firmament.
Absolute Frame of Reference
The idea that the presence of God dwells in a specific place, as a theme, doesn't get picked up until King David wanted to build a temple. Up until that time the Lord used a tabernacle as the center of worship.
February 16th
The Apostle Paul refers to the third heaven in which case, logically, there must also be a first and second heaven. If you believe that Earth orbits a sun which is adrift in an infinite universe, you don't have a third heaven.
Relative Motion
There's no observable difference between heliocentric and Geocentrospheric models because they're two frames of reference in the same system. They coexist.