Night+and+Day+in+chapters+11+and+12-6

Night represents the sin, guilt, and shame that everyone but especially Dimmesdale has. At night is when he reprimands himself for his sins and for the shameful things he has done.

Then the meteor's light which is like day represents truth and elucidating what Chillingworth wants. The night of the meteor he sees Hester, Dimmesdale, and Pearl in between them on the scaffold, it was at that moment that he realized and knew for sure who Hester's lover was.