Midnight

You may be looking for the planet of the same name.

Midnight was the transition time from one day to the next – the moment when the date changed. (TV: A Girl's Best Friend)

The Beltane festival began at midnight on 30 April — that is, the first minute of the first day of May. (TV: The Dæmons)

In the New Year period, particularly during the millennium celebrations from 1999 to 2000, midnight marked the end of 31 December, New Year's Eve and the beginning of the next year on 1 January, New Year's Day. In anticipation, people generally made a countdown to midnight, and fireworks displays were held as the time passed. (TV: Doctor Who, Fragments)

On 1 January 2005, Rose Tyler noted to her mother Jackie that midnight had passed as they walked home to the Powell Estate. (TV: The End of Time)

On 25 December 2006, Jackie acknowledged the passing of midnight commencing Christmas Day shortly after Rose took the newly regenerated Tenth Doctor to bed. (TV: The Christmas Invasion)