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Temps

Time
 
1 solar year = average interval between 2 successive returns of the sun to the first point of Aries.
1 sireal year = average period of revolution of the Earth with respect to the fixed stars.
1 anomalistic year = average interval between successive perihelions
1 solar year (1 astronomical year) = 365.242 mean solar days
1 sireal year = 365.256 mean solar days
1 anomalistic year = 365.259 mean solar days
1 calendar year = 365.25 mean solar days
1 solar day = interval between 2 successive returns of the sun to the meridian
1 mean solar day = average length of solar day over 1 year
1 second = time equal to the duration of 9,192,631,770 periods of radiation corresponding to the transition of the ground state of the Caesium-133 atom.
1 lustrum = 5 years
 
Old English standard
 
1 moment = 1.5 minutes