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Solar noon

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Solar noon

For other uses, see Noon (disambiguation).
"Midday" redirects here. For other uses, see Midday (disambiguation).
"Noon time" redirects here. For the song by Zion I, see Heroes in the City of Dope.
"True Noon" redirects here. For the 2009 film, see True Noon (film).

Noon (also midday or noon time) is usually defined as 12 o'clock in the daytime. However the term midday is used colloquially to refer to a range of time, usually 11-1. The word noon is also used informally to mean midday regarding the location of the sun, as opposed to the middle of one's day. Although this is a time around the middle of the day when people in many countries take a lunch break. Solar noon is 12 o'clock apparent solar time, or around 12 – 1 p.m. local time depending on daylight saving time, the moment when the sun crosses the meridian and is about at its highest elevation in the sky. The clock time of solar noon depends on the longitude and date.[1]

The opposite of noon is midnight.

In many cultures in the Northern Hemisphere, noon had ancient geographic associations with the direction "south" (as did midnight with "north" in some cultures). Remnants of the noon = south association are preserved in the words for noon in French (Midi) and Italian (Mezzogiorno), both of which also refer to the southern parts of the respective countries. Modern Polish and Ukrainian go a step farther, with the words for noon (południe, полудень – literally "half-day") also meaning "south" and the words for "midnight" (północ, північ – literally "half-night", as with English mid(dle) meaning "half") also meaning "north".

Etymology

The word noon is derived from Latin nona hora, the ninth hour of the day, and is related to the liturgical term none. The Roman and Western European medieval monastic day began at 6:00 a.m. (06:00) by modern timekeeping, so the ninth hour started at what is now 3:00 p.m. (15:00). In English, the meaning of the word shifted to midday and the time gradually moved back to 12:00. The change began in the 12th century and was fixed by the 14th century.[2]

Solar noon

Solar noon is the moment when the Sun transits the celestial meridian – roughly the time when it is highest above the horizon on that day ("Sun transit time"). This is also the origin of the terms ante meridiem (am) and post meridiem (pm) as noted below. The Sun is directly overhead at solar noon at the Equator on the equinoxes; at the Tropic of Cancer (latitude 23° 26′ 16″ N) on the June solstice; and at the Tropic of Capricorn (23° 26′ 16″ S) on the December solstice.

Muslims call solar noon as Zawwal (زوال); the dhuhr prayer is offered between midday and the Asr prayer.

Nomenclature

With 12-hour time notation, most authorities recommend avoiding confusion by using "noon", "12 noon", or "12:00 noon".

Digital clocks and computers commonly display 12 p.m. for noon. While that phrase may be used practically, it helps to understand that any particular time is actually an instant. The "p.m." shown on clock displays refers to the 12-hour period following the instant of noon, not to the instant itself.

While computers and digital clocks display "12:00 a.m." and "12:00 p.m." these notations provide no clear and unambiguous way to distinguish between midnight and noon. It is technically improper to use "a.m." and "p.m." when referring to 12:00. The abbreviation a.m. stands for ante meridiem (or before the meridian) and p.m. stands for post meridiem (or after the meridian), with the meridian being 12:00 noon. For this reason, neither abbreviation is correct for noon or midnight.[3] The length of the error is determined by the smallest unit of time: 12:00:01 p.m. would be correctly noted, as would even 12:00:00.00001 pm.

The most common ways to represent these times are:

  • to use a 24-hour clock (00:00 and 12:00, 24:00; but never 24:01)
  • to use "12 noon" or "12 midnight", although unless the person is referring to a general time and not a specific day, "12 midnight" is still ambiguous
  • to specify midnight as between two successive days or dates (Midnight Saturday/Sunday or Midnight December 14/15)
  • to use "12:01 a.m." or "11:59 p.m." This final usage is common in the travel industry, especially train and plane schedules, to avoid confusion as to passengers' schedules

The 30th edition of the U.S. Government Style Manual (2008) sections 9.54 and 12.9b recommends the use of "12 a.m." for midnight and "12 p.m." for noon.[4][5][nb 1]

See also

Notes

References

External links

  • Generate a solar noon calendar for your location
  • U.S. Government Printing Office Style Manual (2008), 30th edition
  • Shows the hour and angle of sunrise, noon, and sunset drawn over a map.
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