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Earth-based: the time it took for the Earth to rotate on its own axis, as observed on a sundial [citation needed]. Units originally derived from this base include the week (seven days), and the fortnight (14 days). Subdivisions of the day include the hour (1/24 of a day), which was further subdivided into minutes and finally seconds. The second ...
An increase of 360° in the ERA is a full rotation of the Earth. A sidereal day on Earth is approximately 86164.0905 seconds (23 h 56 min 4.0905 s or 23.9344696 h). (Seconds are defined as per International System of Units and are not to be confused with ephemeris seconds.)
In this formulation a measurement or calculation of EOT at a certain value of time depends on a measurement or calculation of α at that time. Both α and α M vary from 0 to 24 hours during the course of a year. The former has a discontinuity at a time that depends on the value of UT, while the latter has its at a slightly later time.
t. e. Metric time is the measure of time intervals using the metric system. The modern SI system defines the second as the base unit of time, and forms multiples and submultiples with metric prefixes such as kiloseconds and milliseconds. Other units of time – minute, hour, and day – are accepted for use with SI, but are not part of it.
A minute (min) is 60 seconds in length (or, rarely, 59 or 61 seconds when leap seconds are employed), and an hour is 60 minutes or 3600 seconds in length. A day is usually 24 hours or 86,400 seconds in length; however, the duration of a calendar day can vary due to Daylight saving time and Leap seconds.
In the International System of Units (SI), the unit of time is the second (symbol: s). It has been defined since 1967 as "the duration of 9192631770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom", and is an SI base unit. [ 12 ]
1.8 ks: The time slot for the typical situation comedy on television with advertisements included 2.28 ks: The duration of the Anglo-Zanzibar War, the shortest war in recorded history. 3.6 ks: The length of one hour (h), the time for the minute hand of a clock to cycle once around the face, approximately 1/24 of one mean solar day
Each day contains 24 hours and each hour contains 60 minutes. The number of seconds in a minute is usually 60, but with an occasional leap second, it may be 61 or 59 instead. [10] Thus, in the UTC time scale, the second and all smaller time units (millisecond, microsecond, etc.) are of constant duration, but the minute and all larger time units ...