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.
The Brightness of the Firmament
December 1st
We refer to the life after this one as "heaven" because we haven't paid attention to what the Bible says. We'll eventually live in a new Jerusalem at the the location presently occupied by our Earth.
November 2nd
The Millennial Kingdom is what the Old Testament prophets referred to as "a new heavens and a new Earth," but it's not the new heavens and new Earth that John describes in Revelation chapters 21-22.