The **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 minutes.^{ [3] } In the UTC time standard, a minute on rare occasions has 61 seconds, a consequence of leap seconds; there is also a provision to insert a negative leap second, which would result in a 59-second minute, but this has never happened in more than 40 years under this system.

Al-Biruni first subdivided the hour sexagesimally into minutes, seconds, thirds and fourths in 1000 CE while discussing Jewish months.^{ [4] }

Historically, the word "minute" comes from the Latin *pars minuta prima*, meaning "first small part". This division of the hour can be further refined with a "second small part" (Latin: *pars minuta secunda*), and this is where the word "second" comes from. For even further refinement, the term "third" (1⁄60 of a second) remains in some languages, for example Polish (*tercja*)^{[ citation needed ]} and Turkish (*salise*), although most modern usage subdivides seconds by using decimals. The symbol notation of the prime for minutes and double prime for seconds can be seen as indicating the first and second cut of the hour (similar to how the foot is the first cut of the yard or perhaps chain, with inches as the second cut). In 1267, the medieval scientist Roger Bacon, writing in Latin, defined the division of time between full moons as a number of hours, minutes, seconds, thirds, and fourths (*horae*, *minuta*, *secunda*, *tertia*, and *quarta*) after noon on specified calendar dates.^{ [5] } The introduction of the minute hand into watches was possible only after the invention of the hairspring by Thomas Tompion, an English watchmaker, in 1675.^{ [6] }

- 1 2 "Non-SI units accepted for use with the SI, and units based on fundamental constants".
*Bureau International de Poids et Mesures*. Archived from the original on 2014-11-11. Retrieved 2011-05-25. - ↑ "What is the origin of hours, minutes and seconds?".
*Wisteme*. Archived from the original on 24 March 2012. Retrieved 2011-05-25.What we now call a minute derives from the first fractional sexagesimal place

. - ↑ Nelson, D. (2008). "Prime symbol (accent)".
*The Penguin Dictionary of Mathematics*(4th ed.). Penguin UK. ISBN 978-0141920870. - ↑ Al-Biruni (1879) [1000].
*The Chronology of Ancient Nations*. Translated by Sachau, C. Edward. pp. 147–149. - ↑ R Bacon (2000) [1928].
*The Opus Majus of Roger Bacon*. BR Belle. University of Pennsylvania Press. table facing page 231. ISBN 978-1855068568. - ↑ Mitman, Carl (1926). "The Story of Timekeeping".
*The Scientific Monthly*.**22**(5): 424–427. Bibcode:1926SciMo..22..424M. JSTOR 7652.

- Henry Campbell Black,
*Black's Law Dictionary*, 6th Edition, entry on Minute. West Publishing Company, St. Paul, Minnesota, 1991.^{[ ISBN missing ]} - Eric W. Weisstein. "Arc Minute." From MathWorld –A Wolfram

A **minute of arc**, **arcminute** (arcmin), **arc minute**, or **minute arc**, denoted by the symbol ′, is a unit of angular measurement equal to 1/60 of one degree. Since one degree is 1/360 of a turn, or complete rotation, one arcminute is 1/21600 of a turn. 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 21600 nmi. A minute of arc is π/10800 of a radian.

A **day** is the time period of a full rotation of the Earth with respect to the Sun. On average, this is 24 hours. As a day passes at a given location it experiences morning, noon, afternoon, evening, and night. This daily cycle drives circadian rhythms in many organisms, which are vital to many life processes.

An **hour** is a unit of time historically reckoned as 1⁄24 of a day and defined contemporarily as exactly 3,600 seconds (SI). There are 60 minutes in an hour, and 24 hours in a day.

A **leap second** is a one-second adjustment that is occasionally applied to Coordinated Universal Time (UTC), to accommodate the difference between precise time and imprecise observed solar time (UT1), which varies due to irregularities and long-term slowdown in the Earth's rotation. The UTC time standard, widely used for international timekeeping and as the reference for civil time in most countries, uses TAI and consequently would run ahead of observed solar time unless it is reset to UT1 as needed. The leap second facility exists to provide this adjustment. The leap second was introduced in 1972 and since then 27 leap seconds have been added to UTC.

The **second** 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.

A **metric prefix** is a unit prefix that precedes a basic unit of measure to indicate a multiple or submultiple of the unit. All metric prefixes used today are decadic. Each prefix has a unique symbol that is prepended to any unit symbol. The prefix *kilo-*, for example, may be added to *gram* to indicate *multiplication* by one thousand: one kilogram is equal to one thousand grams. The prefix *milli-*, likewise, may be added to *metre* to indicate *division* by one thousand; one millimetre is equal to one thousandth of a metre.

A **year** is the time taken for astronomical objects to complete one orbit. For example, a year on Earth is the time taken for Earth to revolve around the Sun. Generally, a year is taken to mean a calendar year, but the word is also used for periods loosely associated with the calendar or astronomical year, such as the seasonal year, the fiscal year, the academic year, etc. The term can also be used in reference to any long period or cycle, such as the Great Year.

A **microsecond** is a unit of time in the International System of Units (SI) equal to one millionth of a second. Its symbol is **μs**, sometimes simplified to **us** when Unicode is not available.

**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. Metric time is a measure of time intervals, while decimal time is a means of recording time of day.

**Sexagesimal**, also known as **base 60**, is a numeral system with sixty as its base. It originated with the ancient Sumerians in the 3rd millennium BC, was passed down to the ancient Babylonians, and is still used—in a modified form—for measuring time, angles, and geographic coordinates.

**Babylonian cuneiform numerals**, also used in Assyria and Chaldea, were written in cuneiform, using a wedge-tipped reed stylus to print a mark on a soft clay tablet which would be exposed in the sun to harden to create a permanent record.

An order of magnitude of time is usually a decimal prefix or decimal order-of-magnitude quantity together with a base unit of time, like a microsecond or a million years. In some cases, the order of magnitude may be implied, like a "second" or "year". In other cases, the quantity name implies the base unit, like "century". In most cases, the base unit is seconds or years.

**Mixed radix** numeral systems are non-standard positional numeral systems in which the numerical base varies from position to position. Such numerical representation applies when a quantity is expressed using a sequence of units that are each a multiple of the next smaller one, but not by the same factor. Such units are common for instance in measuring time; a time of 32 weeks, 5 days, 7 hours, 45 minutes, 15 seconds, and 500 milliseconds might be expressed as a number of minutes in mixed-radix notation as:

... 32, 5, 07, 45; 15, 500 ... ∞, 7, 24, 60; 60, 1000

**60** (**sixty**) is the natural number following 59 and preceding 61. Being three times 20, it is called *threescore* in older literature.

A **binary clock** is a clock that displays the time of day in a binary format. Originally, such clocks showed *each decimal digit* of sexagesimal time as a binary value, but presently binary clocks also exist which display hours, minutes, and seconds as binary numbers. Most binary clocks are digital, although analog varieties exist. True binary clocks also exist, which indicate the time by successively halving the day, instead of using hours, minutes, or seconds. Similar clocks, based on Gray coded binary, also exist.

**ISO 6709**, *Standard representation of geographic point location by coordinates*, is the international standard for representation of latitude, longitude and altitude for geographic point locations.

A **degree**, usually denoted by **°**, is a measurement of a plane angle in which one full rotation is 360 degrees.

The **ancient Roman units of measurement** were primarily founded on the Hellenic system, which in turn was influenced by the Egyptian and the Mesopotamian systems. The Roman units were comparatively consistent and well documented.

**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 time system used in France from 1794 to 1800, during the French Revolution, which divided the day into 10 decimal hours, each decimal hour into 100 decimal minutes and each decimal minute into 100 decimal seconds, as opposed to the more familiar standard time, which divides the day into 24 hours, each hour into 60 minutes and each minute into 60 seconds.

A **moment** is a medieval unit of time. The movement of a shadow on a sundial covered 40 moments in a solar hour, a twelfth of the period between sunrise and sunset. The length of a solar hour depended on the length of the day, which, in turn, varied with the season. Although the length of a moment in modern seconds was therefore not fixed, on average, a medieval moment corresponded to 90 seconds. A solar day can be divided into 24 hours of either equal or unequal lengths, the former being called natural or equinoctial, and the latter artificial. The hour was divided into four *puncta* (quarter-hours), 10 *minuta*, or 40 *momenta*.

This page is based on this Wikipedia article

Text is available under the CC BY-SA 4.0 license; additional terms may apply.

Images, videos and audio are available under their respective licenses.

Text is available under the CC BY-SA 4.0 license; additional terms may apply.

Images, videos and audio are available under their respective licenses.