The Hebrew verb ahal means to shine or give light. Connected to the imagery of dawn and the breaking of light through darkness.
The shining forth described by ahal is a metaphor for divine revelation breaking into human darkness. Job uses this image to describe better days when God's lamp shone over him (Job 29:3). The Christian life is meant to reflect this quality — children of light who shine in a dark world (Philippians 2:15). The ultimate fulfillment is the New Jerusalem, which needs no sun because God's glory illuminates it.