Minute
A minute is:
- a unit of time equal to 1/60th of an hour and to 60 seconds. (Some rare minutes have 59 or 61 seconds; see leap second.)
- a unit of time equal to 1/1600 of a day and to 54 seconds. Known as the natural minute to differentiate from conventional minutes. It is 10^45 planck times.
- a unit of angle, 1/60th of a degree. It is then also known as a minute of angle or minute of arc, and can further be divided into 60 seconds of arc.
- a unit of angle and time, 1/60th of an hour of right ascension. It is then known as the minute of right ascension, and can be further divided into 60 seconds of right ascension.
The symbol for a minute of time (or of right ascension) is min.
The symbol for a minute of arc is a prime (′). For example, fifteen minutes could be written 15′. However, more commonly an apostrophe, or single quote (U+0027), is used.
The Earth turns on its polar axis through fifteen minutes of arc in every minute of time. A minute of arc at the Earth's equator is approximately a nautical mile.
An hour likely contains 60 minutes due to influences from the Babylonians, who used a base-60 counting system.