Definition of Mean noon. Meaning of Mean noon. Synonyms of Mean noon

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Definition of Mean noon

Mean noon
Mean Mean, a. [OE. mene, OF. meiien, F. moyen, fr. L. medianus that is in the middle, fr. medius; akin to E. mid. See Mid.] 1. Occupying a middle position; middle; being about midway between extremes. Being of middle age and a mean stature. --Sir. P. Sidney. 2. Intermediate in excellence of any kind. According to the fittest style of lofty, mean, or lowly. --Milton. 3. (Math.) Average; having an intermediate value between two extremes, or between the several successive values of a variable quantity during one cycle of variation; as, mean distance; mean motion; mean solar day. Mean distance (of a planet from the sun) (Astron.), the average of the distances throughout one revolution of the planet, equivalent to the semi-major axis of the orbit. Mean error (Math. Phys.), the average error of a number of observations found by taking the mean value of the positive and negative errors without regard to sign. Mean-square error, or Error of the mean square (Math. Phys.), the error the square of which is the mean of the squares of all the errors; -- called also, especially by European writers, mean error. Mean line. (Crystallog.) Same as Bisectrix. Mean noon, noon as determined by mean time. Mean proportional (between two numbers) (Math.), the square root of their product. Mean sun, a fictitious sun supposed to move uniformly in the equator so as to be on the meridian each day at mean noon. Mean time, time as measured by an equable motion, as of a perfect clock, or as reckoned on the supposition that all the days of the year are of a mean or uniform length, in contradistinction from apparent time, or that actually indicated by the sun, and from sidereal time, or that measured by the stars.

Meaning of Mean noon from wikipedia

- minutes before or after noon GMT, a discrepancy described by the equation of time. Noon GMT is the annual average (the arithmetic mean) moment of this event...
- UT is needed because UT is zero at mean midnight while GMHA = 0 at mean noon. Universal Time is discontinuous at mean midnight so another quantity day number...
- since 1847. In contrast, astronomical GMT began at mean noon, i.e. astronomical day X began at noon of civil day X. The purpose of this was to keep one...
- time since "1900, Jan. 0, Greenwich Mean noon", measured in Julian centuries of 36,525 days. The Sun's geometric mean longitude, freed from aberration is...
- unique mean. For example, the times an hour before and after midnight are equidistant to both midnight and noon. It is also possible that no mean exists...
- represented: in English-speaking countries, "12 p.m." indicates 12 o'clock noon, while "12 a.m." means 12 o'clock midnight. The natural day-and-night division...
- epoch J2000.0. It is exactly 12:00 TT (close to but not exactly Greenwich mean noon) on January 1, 2000 in the Gregorian (not Julian) calendar. Julian within...
- "1900 January 0 at 12 hours ephemeris time". 1900 January 0 (at Greenwich Mean Noon) was also the epoch used by Newcomb's Tables of the Sun, which became...
- saving time. Julian day number is a count of days elapsed since Greenwich mean noon on 1 January 4713 B.C., Julian proleptic calendar. The Julian Date is...
- the Tables, pp. 9 and 20, citing time units of Greenwich Mean Noon, Greenwich Mean Time, and mean solar day W de Sitter, on p. 38 of Bulletin of the Astronomical...