second unit Comparison Table

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second unit comparison table

Subject has historical origin is an instance of is an acronym for has symbol has value has definition

ephemeris second second unit 1/31556925.97474 tropical year The length of a tropical second (1/31556925.97474 of the tropical year) on 1900 January 0.5 ephemeris time.

leap second second unit A second (see second, Système International) added between 60^s and 0^s at announced times to keep UTC within 0^s.90 of UT1. Generally, leap seconds are added at the end of June or December.

mean solar second second unit 1/86400 mean solar day 1/86400 of a mean solar day (cf. ephemeris second).

second was defined originally as the fraction 1/86400 of the mean solar day base SI unit Syteme Internationale s duration of 9192631770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom

Subject	has historical origin	is an instance of	is an acronym for	has symbol	has value	has definition
ephemeris second		second unit			1/31556925.97474 tropical year	The length of a tropical second (1/31556925.97474 of the tropical year) on 1900 January 0.5 ephemeris time.
leap second		second unit				A second (see second, Système International) added between 60^s and 0^s at announced times to keep UTC within 0^s.90 of UT1. Generally, leap seconds are added at the end of June or December.
mean solar second		second unit			1/86400 mean solar day	1/86400 of a mean solar day (cf. ephemeris second).
second	was defined originally as the fraction 1/86400 of the mean solar day	base SI unit	Syteme Internationale	s		duration of 9192631770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom

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