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Topic: Equation of time

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	Equation of time - Wikipedia, the free encyclopedia
		This difference, known as the equation of time, results from an irregular movement of the Sun caused by a combination of the obliquity of the Earth's rotation axis and the eccentricity of its orbit.
		The equation of time is visually illustrated by an analemma.
		The Equation of Time and the Analemma, by Kieron Taylor
	en.wikipedia.org /wiki/Equation_of_time (1454 words)

	Equation of Time
		Solar time, or true solar time, which was the time shown on the sundials of the past.
		Equation of time is the difference between mean solar time and true solar time.
		In “astronomical” watches and clocks, equation of time is often enhanced with sidereal time, the phases and age of the moon, a perpetual ca-lendar, the times of sunrise and sunset and the sun’s declination, the movement of the planets, the map of the skies, or the ephémérides (solstices, equinoxes, seasons).
	www.antiquorum.com /html/vox/vox2003/equation/equation.html (1240 words)

	Eccentricity, Obliquity, Analemma (Site not responding. Last check: 2007-10-21)
		The length of time between one sun crossing the meridian and another sun's crossing is defined as the "equation of time".
		From the above diagram, it is clear that the total equation of time is equal to the sum of the equation of time due to the eccentricity and the obliquity.
		The equation of time due to eccentricity is calculated from the total equation of time minus the equation of time due to obliquity.
	members.aol.com /jwholtz/analemma/eq-of-time.htm (983 words)

	The Dark Days of Winter (Site not responding. Last check: 2007-10-21)
		In any time zone, the Equation of Time is simply the difference between 12:00 noon on a clock and the actual time of the Sun's transit (sundial noon) across the central meridian of the time zone.
		Thus in late December it is the Equation of Time that has the dominant influence over the changes in sunrise and sunset times from one day to the next.
		In the weeks before solstice, the two effects act in opposite directions on the time of sunset: the declination effect pulling it earlier and the Equation of Time pushing it later.
	aa.usno.navy.mil /faq/docs/dark_days.html (691 words)

	mueller
		The response of the equation of time to a variation of its key parameters is analyzed.
		The natural unit of time is the rotation of the earth, that is the apparent daily course of the sun.
		Since the equation of time is to be examined during a year, the earth can be supposed to always have the same direction in space, i.e., we will not take into account precession and nutation.
	info.ifpan.edu.pl /firststep/aw-works/fsII/mul/mueller.html (3248 words)

	Equation of time - Wikipedia, the free encyclopedia (Site not responding. Last check: 2007-10-21)
		The diameter of the Sun as seen from the Earth is about 1/2 degree, so it moves by its own radius every minute.
		From one year to the next, the equation of time can vary by as much as 20 seconds[1] (http://www.sunlitdesign.com/infosearch/sundialaccuracy.htm).
		The Equation of Time and the Analemma, by Kieron Taylor (http://myweb.tiscali.co.uk/moonkmft/Articles/EquationOfTime.html)
	www.collegestation.us /project/wikipedia/index.php/Equation_of_time (1736 words)

	PlanetPhysics: time independent Schrödinger equation
		The Schrödinger equation can be a little intimidating the first time you see it.
		Using a potential independent of time allows us to use one of a few tools for analyticaly solving partial differential equations, separation of variables[2].
		This is version 10 of time independent Schrödinger equation, born on 2006-01-04, modified 2006-03-30.
	planetphysics.org /encyclopedia/TimeIndependentSchrodingerEquation.html (393 words)

	The Equation of Time (Site not responding. Last check: 2007-10-21)
		If the earth's equator were lying in the same plane at the the earth's orbit, with the earth orbiting the sun in a circle with a constant velocity, then the sun would appear to move purely eastward on the celestial equator at that constant speed.
		Note that the equation of time is not exactly zero at the solstices, but instead is zero a few days before the June solstice and a few days after the December solstice.
		Then from the equation of time table we see that sunrise and sunset would happen earliest in mid-February, when the sun is especially far east, and latest in mid-November when the sun is especially far west.
	da.saao.ac.za /sky/eqntime.html (1633 words)

	Time Scales
		The earliest almanacs tabulated the equation of time.
		Although the term GMT was not explicitly used, the standard time for legal purposes in the United States specified by 15USC261 (the Calder Act) was defined to be based on the mean astronomical time of meridians spaced at 15-degree intervals west of Greenwich; i.e., GMT.
		Although the term GMT was not explicitly used, the standard time for legal purposes in the United States specified by 15USC261 was clarified and reaffirmed to be based on the mean solar time of meridians spaced at 15-degree intervals west of Greenwich; i.e., GMT.
	www.ucolick.org /~sla/leapsecs/timescales.html (12419 words)

	www.blancpain.com : Blancpain - Manufacture of Watchmaking Art - Swiss Master Watchmakers since 1735 (Site not responding. Last check: 2007-10-21)
		Equation of time is a physical effect of what to some might seem to be defects.
		The incorporation of Equation of Time displays as a complication has historically been reserved for the most exotic and most important time pieces.
		Thus the difference, Equation, can be determined by noting the difference between the time shown on the normal minute hand (Civil Time) and the time shown on the Real Solar Time hand.
	www.blancpain.com /e/best_articles/EM_part_I.html (1374 words)

	EOT watches, Equation of Time watches, Roland Murphy, RGM watches
		EOT watches were created as the culmination of a fascinating project that occured on the EOT web site: a collaboration between forum members to design an affordable watch from a consensus decision.
		EOT watches are available for sale to the public and are selling very well -- which is no surprise given the tremendous quality for relatively little money.
		EOT now has a dedicated Collaboration Forum where anyone is welcome to participate in designing the new watches.
	www.watchfinder.net /brands/EOTwatches.htm (389 words)

	Astrolabe
		The equation of time was known, of course; but, you would not be concerned with the equation of time for telling the current (true local solar) time.
		Read-off the equation of time correction from the scale on the dioptra and subtract.
		The rete is a stereographic projection of the celestial-sphere onto its equator, with the eye-point at the south-pole, as illustrated.
	www.rism.com /Trig/astrolabe.htm (3347 words)

	Interesting Thing of the Day: The Equation of Time
		The time differences had nothing to do with the outcome of the war, but the reason for the differences was quite interesting indeed.
		It was not until 1883 that standard time zones were first adopted (thus eliminating the problem of local variations in mean solar time); they became law in the U.S. in 1918.
		This equation (or a table derived from it) is what you need to use if you have a sundial in your garden, since it will almost always be out of sync with your clocks.
	itotd.com /articles/289 (787 words)

	Equation of Time (Site not responding. Last check: 2007-10-21)
		Equation of Time and its affects on Sunrise in January
		The phenomena known as the equation of time describes the differences in time between the noon passages of the apparent sun and the mean sun or apparent time minus mean time.
		The apparent motion of the sun as it crosses the sky is mostly affected by the earth's rotation.
	www.srh.noaa.gov /ewx/html/wxevent/2003/eoftw.htm (417 words)

	The Equation of Time
		The angle between the planes of the Equator and the Earth's orbit around the Sun is called the angle of Obliquity.
		This projection will be a maximum when the great circles of the Equator and the Ecliptic are parallel (at the summer and winter solstices) and will be a minimum where the great circles are at their largest angle (at the equinoxes).
		The total of these two effects gives the Equation of Time, which is formally defined as the difference between clock time and apparent solar time.
	www.indwes.edu /Faculty/bcupp/Things/Greenwich/Equation.html (642 words)

	Private Preview 2005: Blancpain's Equation of Time Marchante \| Robb Report
		Equation of time is a mechanism designed to measure the difference between mean time—the established system based on a 24-hour day—and the sun’s actual progress across the sky.
		The grandiosely titled equation of time is a mechanism designed to measure the difference between mean time—the established system based on a 24-hour day—and the sun’s actual progress across the sky.
		Solar time, which is skewed by the earth’s elliptical orbit, can vary by as much as 16 minutes a day—plus or minus—depending on the time of year.
	www.robbreport.com /Articles/Style/Timepieces/Private-Preview-2005-Blancpains-Equation-of-Time-Marchante.asp (359 words)

	The Equation of Time
		Part of the jargon invented to deal with the situation is "sun time", the time a sundial would tell, and "mean time", the time an accurate clock would tell.
		The real equation involves transforming the motion of the Sun in the ecliptic (which would be constant were the Earth's orbit a circle) into the apparent motion relative the equator.
		On the equator, the equation of time is the only significant adjustment in the time of sunrise, sunset, and the meridian passage.
	werme.8m.net /eqoftm.html (1019 words)

	Sundials on the Internet - the Equation of Time
		The first is that the plane of the Equator is not the same as the plane of the Earth's orbit around the sun, but is offset from it by the angle of obliquity.
		The second is that the orbit of the Earth around the sun is an ellipse and not a circle, and the apparent motion of the sun is thus not exactly equal throughout the year.
		If you want to know the Equation of Time for every day of the year, there is a table in Appendix A of the book by Waugh.
	www.sundials.co.uk /equation.htm (2283 words)

	Equation of Time
		However this is not the case, so a Sundial (which shows Real Solar time) differs from the Mean time by the Equation of Time.
		The equation of time data is usually represented graphically for ease in use.
		We see that the equation of time for October 18 is about 14 minutes fast, when we subtract this from the dial time we get 11:46 which is the Local Standard Time and will agree with our watch!
	pw1.netcom.com /~abraxas2/eot.htm (250 words)

	Equation of Time
		Both effects combine to create an offset in the time of local noon (and those of sunrise and sunset) by as much as +/- 16 min: this is the equation of time.
		Around winter solstice, the daily change in the equation of time happens to be more important than the daily change in the length of the day, causing the phenomenon you so keenly observed.
		The equation of time is often represented by a figure 8.
	imagine.gsfc.nasa.gov /docs/ask_astro/answers/980116c.html (433 words)

	Equation of Time : Ellipse (Site not responding. Last check: 2007-10-21)
		Because of the nature of its orbit, the pattern of its analemma is dominated by the ellipse aspect of the equation of time, and so the resulting figure has a single period rather than a double period, and the analemma does not cross itself.
		This is a picture of the sun traced over the course of a year when standing on the equator, and the very large variation of the sun's position is apparent.
		The combined effects of these form an equation of time that cause the sun to be ahead or behind almost 100 minutes, giving a 200 minute variation throughout the course of the year.
	archive.ncsa.uiuc.edu /Classes/MATH198/matownse/others.html (506 words)

	Tudor Jones - Equation of Time.
		Mean time is used by our society instead of solar time because of the differing length of the solar day (noon to noon) throughout the year.
		The second factor of the Equation of Time concerns the 23½ degree inclination of the Earth's axis to the plane of its orbit.
		The time it takes the Sun to move between the ecliptical (?) meridian and the equatorial meridian is the time that forms part of the equation of time.
	www.storm.ca /~tjones/equation.html (1682 words)

	Equation of Time · Astrological definition of Equation of Time · Astrology Encyclopedia
		One sometimes hears the suggestion that the Figure should be erected by the Sun and not by the clock, which would involve the application of the Equation of Time as a correction of clock time.
		Its application to the erecting of the Figure, however, would be utterly unsound, for the time in which the birth is stated and the ephemerides which give the planets' places are both based on mean time.
		If the Figure were to be erected for apparent time, the birth moment would have to be corrected to apparent time, and the result would be the same.
	www.astrologyweekly.com /dictionary/equation-of-time.php (1086 words)

	LATEST SUNRISE, EARLIEST SUNSET, AND THE 'EQUATION OF TIME'
		However, times of sunrise, noon and sunset (being determined by Earth's daily rotation) relate more easily to the sun's Celestial Longitude - whose labels (along the Celestial Equator) are direct projections out from Earth's equator.
		Thus, times of sunrise (and indeed sunset) from January to March are later than they would be if Earth's orbit was circular and if our spin-axis was 'upright'.
		This graph is known as the Equation of Time - which may be described as the daily and seasonal difference between sundial time and clock time.
	meltingpot.fortunecity.com /melwood/368/eqntime.html (619 words)

	Astronomy Without a Telescope (Site not responding. Last check: 2007-10-21)
		Part of the non-uniformity is due to the fact that on top of the general eastward drift among the stars, the Sun is moving along the ecliptic northward or southward with respect to the celestial equator.
		Apparent solar time is based on the component of the Sun's motion parallel to the celestial equator.
		The Equation of Time explains why, according to your clock, the earliest sunset and latest sunrise is not at the winter solstice.
	www.astronomynotes.com /nakedeye/s9.htm (353 words)

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