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  2. Minute and second of arc - Wikipedia

    en.wikipedia.org/wiki/Minute_and_second_of_arc

    The nautical mile (nmi) was originally defined as the arc length of a minute of latitude on a spherical Earth, so the actual Earth circumference is very near 21 600 nmi. A minute of arc is ⁠π 10 800⁠ of a radian. A second of arc, arcsecond (arcsec), or arc second, denoted by the symbol ″, [2] is ⁠ 1 60 ⁠ of an arcminute, ⁠ 1 3600 ...

  3. Unit of time - Wikipedia

    en.wikipedia.org/wiki/Unit_of_time

    The TU (for time unit) is a unit of time defined as 1024 μs for use in engineering. The Svedberg is a time unit used for sedimentation rates (usually of proteins). It is defined as 10 −13 seconds (100 fs). The galactic year, based on the rotation of the galaxy and usually measured in million years.

  4. Decimal time - Wikipedia

    en.wikipedia.org/wiki/Decimal_time

    The large dial shows the ten hours of the decimal day in Arabic numerals, while the small dial shows the two 12-hour periods of the standard 24-hour day in Roman numerals. Decimal time is the representation of the time of day using units which are decimally related. This term is often used specifically to refer to the French Republican calendar ...

  5. Equation of time - Wikipedia

    en.wikipedia.org/wiki/Equation_of_time

    From 1767 to 1833, the British Nautical Almanac and Astronomical Ephemeris tabulated the equation of time in the sense 'add or subtract (as directed) the number of minutes and seconds stated to or from the apparent time to obtain the mean time'. Times in the Almanac were in apparent solar time, because time aboard ship was most often determined ...

  6. Second - Wikipedia

    en.wikipedia.org/wiki/Second

    The second (symbol: s) is the unit of time in the International System of Units (SI), historically defined as 1⁄86400 of a day – this factor derived from the division of the day first into 24 hours, then to 60 minutes and finally to 60 seconds each (24 × 60 × 60 = 86400). The current and formal definition in the International System of ...

  7. Minute - Wikipedia

    en.wikipedia.org/wiki/Minute

    Non-SI units. 1 / 60 ⁠ h. Minute is a unit of time defined as equal to 60 seconds. [1] One hour contains 60 minutes. [2] Although not a unit in the International System of Units (SI), the minute is accepted for use in the SI. [1] The SI symbol for minutes is min (without a dot). The prime symbol ′ is also sometimes used informally to denote ...

  8. Metric time - Wikipedia

    en.wikipedia.org/wiki/Metric_time

    1.67 minutes (or 1 minute 40 seconds) 10 3: kilosecond: 1 000: 16.7 minutes (or 16 minutes and 40 seconds) 10 6: megasecond: 1 000 000: 11.6 days (or 11 days, 13 hours, 46 minutes and 40 seconds) 10 9: gigasecond: 1 000 000 000: 31.7 years (or 31 years, 252 days, 1 hour, 46 minutes, 40 seconds, assuming that there are 7 leap years in the interval)

  9. Hour - Wikipedia

    en.wikipedia.org/wiki/Hour

    An hour (symbol: h; [1] also abbreviated hr) is a unit of time historically reckoned as 1 ⁄ 24 of a day and defined contemporarily as exactly 3,600 seconds . There are 60 minutes in an hour, and 24 hours in a day. The hour was initially established in the ancient Near East as a variable measure of 1 ⁄ 12 of the night or daytime.