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 Second Heaven
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.
The Pillars of Heaven
Most English versions translate the pillars of heaven as the foundations of heaven, or the foundations of the heavens, so there may or may not be actual pillars in heaven which we have to account for.
The Foundations of Heaven
Knowing how the firmament is constructed lets us interpret scripture and account for empirical observations of the cosmos, including 90% of the mass of the universe that mainstream science (SciPop) can't find.
CSI: Hebrew
Searching for meaning in the original Hebrew presents a problem of the variety that makes us wonder if the Theologians of old had a clue, and, if they did, did they figure that they could fudge it because no one would notice?
Riding the Heavens
The idea that God or his agents may physically visit the Earth by riding on a piece of heaven may seem ridiculous. However it appears that a section of firmament is used like an elevator to travel between heaven and Earth.
The Waters Above
The firmament, third heaven, originally had a portion of the deep covering its outer surface. At the time of Noah's flood the windows of heaven opened and the water poured through and flooded the Earth.
The Three Heavens
Given that the apostle Paul specifically refers to something called the third heaven it's not a stretch to conclude that there must also be a first and a second heaven. We need to know what they are.
The Windows of Heaven
The windows of heaven are described in scripture as physical structures which may be opened or closed. This is possible because the firmament is a sphere of rigid crystal on the edge of space.
The Lake of Fire
An issue regarding the establishment of the Millennial Kingdom which we have to resolve is: What and where is the lake of fire? It may be the planet Venus.