We can deduce that the firmament, a rigid sphere of crystal on the edge of space which has been detected by the Voyager and New Horizons space missions, shines as brightly as the sun by comparing two passages.
The Righteous Will Shine
The Brightness of the Firmament
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.
February 11th
The firmament gives us a source of light for the second and third 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.