One of the most well known events in the science vs. faith fiasco was a match up between Ken Ham and Bill Nye. The debate between was on the question "Is Creation A Viable Model of Origins?"
In popular science (SciPop) the reason why we can detect a distant brightness is because opposing forces, the solar wind pushing out and interstellar forces pushing in, cause glowing Hydrogen to accumulate, like foam on a beach.
The creation of gravity and formation of the firmament was to establish a place, heaven, where God would dwell in perpetual light because the firmament is bright like the sun, as we see from Daniel.
Outer darkness is only referred to three times in scripture, but by using context we can establish what and where it is. The easiest thing to take for context is the gnashing of teeth, which occurs nine times in the Bible.
And they that be wise shall shine as the brightness of the firmament; and they that turn many to righteousness as the stars for ever and ever.
One of our favorite ways to study the Bible is to follow a doctrine through from the first time it's mentioned to the last. This is a great way to develop understanding of the doctrine in the broad narrative of scripture.
God gave us free will so that believing in Him is a choice. If proof of God was in plain sight then there's no free will. God covered the proof of his presence, the firmament, as part of the plan of redemption.
The firmament gives us a source of light for the 2nd and 3rd days of creation, a source of water for Noah’s flood, literal windows of heaven and we can account for all empirical observations of the cosmos.
When the new Jerusalem comes down from God out of heaven, the Earth will be gone. What does the new Jerusalem come down to? What can we deduce about the new Earth of Revelation 21?