Webster's Online Dictionary
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Specialty Expressions: EPHEMERIS SECOND

ExpressionsDomainDefinition
Ephemeris secondAerospaceThis was the fundamental unit of time of the International System of Units of 1960: 1/31556925.9747 of the tropical year defined by the mean motion of the sun in longitude at the epoch 1900 January 0 day 12 hours. See ephemeris time. See second for the definition of the latest unit of time in the SI system or look on the WWW version of the National Institute of Standards and Technology: Physics Laboratory's International System of Units (SI). Abbreviation s. (references)

Source: compiled by the editor from various references; see credits.

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