From tonight's Vespers:
O Radiant Dawn, splendor of eternal light, sun of justice: come, shine on those who dwell in darkness and the shadow of death.
This is my favorite O Antiphon. I love sunrises--they're the only thing that ever makes it worth getting up early. And there's that serendipitous Sun/Son homophone that we English-speakers enjoy. Also, there is a tradition that at the Second Coming (which is what we are rehearsing for with our yearly celebration of Advent and Christmas), Our Lord will appear in the east: "For as lightning comes from the east and flashes to the west, so also will the coming of the son of man be." (Matt.24:27) Today's concluding prayer also references that final advent:
Hear in kindness, O Lord, the prayers of your people, that those who rejoice at the coming of your Only Begotten Son in our flesh may, when at last he comes in glory, gain the reward of eternal life.