Temps

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

1 moment = 1.5 minutes