Minute

This article is about the unit of time, angle and right ascension. For other uses of the word, see Minute (disambiguation).

See also: Minute of arc

A minute is a unit of measurement of time or of angle. The minute is a unit of time equal to 1/60th (the first sexagesimal fraction^[1]) of an hour or 60 seconds. In the UTC time scale, a minute on rare occasions has 59 or 61 seconds; see leap second. The minute is not an SI unit; however, it is accepted for use with SI units.^[2] The SI symbol for minute or minutes is min (for time measurement) or apostrophe after a number, eg 5' (for angle measurement, even if it is informally used for time).

Astronomy

In astronomy, the minute is a unit of angle, the minute of right ascension. It is equal to 1/60th of an hour of right ascension and can be further divided into 60 seconds of right ascension.

The Earth turns on its polar axis through fifteen minutes of arc in every minute of sidereal time. One minute of arc at the Earth's equator is approximately one nautical mile.

In old astronomical texts minute can also mean a unit of time equal to 1/60th of a day (24 usual minutes). These minutes correspond to the Latin diei scrupulis, and used to express periods of planetary motions. For example, Kepler in Harmonices Mundi gives Saturn year as 10759D12', that is 10759 (Earth) days, 4 hours, and 48 (usual) minutes (roughly 29.5 years),

See also

• International System of Units
• Latitude and longitude

References

1. ^ "What is the origin of hours, minutes and seconds?". Wisteme. http://www.wisteme.com/question.view?targetAction=viewQuestionTab&id=1768. Retrieved 2011-05-25. "What we now call a minute derives from the first fractional sexagesimal place" 
2. ^ "Non-SI units accepted for use with the SI, and units based on fundamental constants". Bureau International de Poids et Mesures. http://www.bipm.org/en/si/si_brochure/chapter4/table6.html. Retrieved 2011-05-25. 

• Henry Campbell Black, Black's Law Dictionary, 6th Edition, entry on Minute. West Publishing Company, St. Paul, Minnesota, 1991.
• Eric W. Weisstein. "Arc Minute." From MathWorld -- A Wolfram