Lo in the orient when the gracious light
Lifts up his burning head, each under eye
Doth homage to his new-appearing sight,
Serving with looks his sacred majesty;
The sun is considered kingly among the heavenly bodies in the old  Ptolemaic astronomy  system. The “Orient”, meaning the East, is where the sun is worshipped. 
 The  exclamatory  “Lo” is an archaic word meaning “behold” or “look”. It has associations with religious fervour.
Sonnet 7