Midnight

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Midnight

 

the moment at which, for a given point on earth, the center of the sun (the true sun or the mean sun) is in the lower culmination. The apparent midnight corresponds to a meridian transit by the true sun, while the mean midnight corresponds to a transit by the mean sun. The time at which midnight occurs depends on the geographic longitude. Midnight begins one hour later for every 15° of longitude to the west. All data in astronomical almanacs are calculated for mean midnight at the Greenwich meridian, from which universal time is figured.