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Equation of Time
I am preparing a presentation on the Equation of Time and have been
trying to find a clear description, preferable with diagrams, of the adjustment due to obliquity. The explanation at the National Maritime Museum http://www.nmm.ac.uk/server/show/conWebDoc.351 only makes sense if you already know the answer The best I could find was the page at http://www.wallingfordclock.talktalk.net/Sidereal%20Time.htm but I still find it inadequate. The example of the bus going down the incline is good to show the slowdown but I cannot find anything appropriate to explain the speeding up. Has anyone seen and better presented explanations? -- Les Desser (The Reply-to address IS valid) |
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Equation of Time
On Apr 25, 12:47*pm, Les Desser wrote:
I am preparing a presentation on the Equation of Time and have been trying to find a clear description, preferable with diagrams, of the adjustment due to obliquity. The explanation at the National Maritime Museum http://www.nmm.ac.uk/server/show/conWebDoc.351 only makes sense if you already know the answer The best I could find was the page at http://www.wallingfordclock.talktalk.net/Sidereal%20Time.htm but I still find it inadequate. The example of the bus going down the incline is good to show the slowdown but I cannot find anything appropriate to explain the speeding up. Has anyone seen and better presented explanations? -- Les Desser (The Reply-to address IS valid) There is only one accurate explanation of the Equation of Time in existence and even that is incomplete - http://www.xs4all.nl/~adcs/Huygens/06/kort-E.html The Equation of Time creates the 24 hour day out of the natural noon cycle - "the Earth...makes an entire revolution in the Ecliptick in 365 days, 5 hours 49 min. or there about, and that those days, reckon'd from noon to noon, are of different lenghts; as is known to all that are vers'd in Astronomy. Now between the longest and the shortest of those days, a day may be taken of such a length, as 365 such days, 5. hours &c. (the same numbers as before) make up, or are equall to that revolution: And this is call'd the Equal or Mean day, according to which the Watches are to be set; and therefore the Hour or Minute shew'd by the Watches, though they be perfectly Iust and equal, must needs differ almost continually from those that are shew'd by the Sun,..But this Difference is regular, and is otherwise call'd the Aequation," Huygens The Equation of Time also keeps one of these 24 hour days elapsing into the next 24 hour day,Monday into Tuesday ect. When Copernicus discovered that the orbital motion of the Earth around the central Sun accounted for the observed behavior of the other planets,it left axial rotation to explain the daily cycle.When axial rotation was discovered,the timekeeping astronomers applied the Equation of Time (EOT) principles to terrestrial geometry and geography,they did not have to assume axial rotation to be constant but as the EOT facility which keeps the 24 hour day to natural noon,they exploited this principle which allows axial rotation to be considered constant as a convenience and not as an observation.It is tricky the way it all works but the actual astronomical means is nothing like the fiction of the NMM treatment. It is absolutely crucial to understand what the Equation of Time actually represents in terms of axial and orbital motions,provisionally,it represents a rate of change using natural noon as a benchmark without going into further details. Of course most here do not recognise variations in the difference between natural noon and 24 hour clock noon as the irreducable complexity of the solar/sidereal fiction requires noon cycles to be equal,the distance the Earth travels in its orbit must correspond to .986 degrees/3 min 56 sec in order to conclude that the Earth rotates through 360 degrees in 23 hours 56 minutes 04 seconds - http://en.wikipedia.org/wiki/Image:T...3%A9reo.en.png If you can explain the Equation of Time with the graphic above then good for you,the fact that it is pure fiction hardly matters to those who will comfortably give you advice in regards to the Equation of Time yet still believe the Earth rotates through 360 degrees in 23 hours 56 minutes 04 seconds.Think of it as Piltdown man to the power of 100 when you get your replies. |
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Equation of Time
"Les Desser" wrote in message ... I am preparing a presentation on the Equation of Time and have been trying to find a clear description, preferable with diagrams, of the adjustment due to obliquity. The explanation at the National Maritime Museum http://www.nmm.ac.uk/server/show/conWebDoc.351 only makes sense if you already know the answer The best I could find was the page at http://www.wallingfordclock.talktalk.net/Sidereal%20Time.htm but I still find it inadequate. The example of the bus going down the incline is good to show the slowdown but I cannot find anything appropriate to explain the speeding up. Has anyone seen and better presented explanations? Does this have what you're looking for http://www.analemma.com/ ? |
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Equation of Time
OG wrote:
Does this have what you're looking for http://www.analemma.com/ Great explanation there, with lots of diagrams and animations. Nice work. -- Pd |
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Equation of Time
On Apr 25, 8:15*pm, "OG" wrote:
"Les Desser" wrote in message ... I am preparing a presentation on the Equation of Time and have been trying to find a clear description, preferable with diagrams, of the adjustment due to obliquity. The explanation at the National Maritime Museum http://www.nmm.ac.uk/server/show/conWebDoc.351 only makes sense if you already know the answer The best I could find was the page at http://www.wallingfordclock.talktalk.net/Sidereal%20Time.htm but I still find it inadequate. The example of the bus going down the incline is good to show the slowdown but I cannot find anything appropriate to explain the speeding up. Has anyone seen and better presented explanations? Does this have what you're looking forhttp://www.analemma.com/ ?- Hide quoted text - - Show quoted text - Are you quite finished with this late 17th century nonsense ?. If genuine and serious investigators could spot how Piltdown man was a hoax then the astronomical equivalent is probably the sidereal/solar fiction first and then this hoax known as the analemma.People who promote variations in axial inclination to the Sun just do not know any better and shouldfd be left to their own devices,you included. The variations in natural noon cycle arise directly from the orbital motion of the Earth,specifically the difference between constant axial rotation and changing orbital oreintation as a component of orbital motion,nothing more and nothing less.The Earth is not a machine where its components act like cogs in a machine insofar as it is fine to inspect the individual axial and orbital motions and orientations and determine what effects they account for but the trouble is that the reasoning which generates the 'analemma' hoax is based on combined axial and orbital motions as a single compound motion.I do not know how you manage to keep the Earth tilting back and forth to the Sun while keeping its rotational orientation fixed to Polaris,but then again,you reason off a constant 24 hour noon cycle,determine no variations in orbital distance ect ,ect.The Equation of Time creates the 24 hour day out of the determination of natural noon but somehow you turn this around to use the 24 hour day to determine the location of the Sun in the sky or the notorious figure - 8,for an astronomer looking on ,at least one familiar with what the Equation of Time does,this is bewildering. In a few sentences ,the treatise of Huygens and his exposition of the correct method jettisons this silly analemma attached to the Equation of Time - "Draw a Meridian line upon a floor (the manner of doing which is sufficiently known; and note, that the utmost exactness herein is not necessary and then hang two plummets, each by a small thred or wire, directly over the said Meridian, at the distance of some 2. feet or more one from the other, as the smalness of the thred will admit. When the middle of the Sun (the Eye being placed so, as to bring both the threds into one line) appears to be in the same line exactly you are then immediately to set the Watch, not precisely to the hour of 12. but by so much less, as is the Aequation of the day by the Table." Huygens http://www.xs4all.nl/~adcs/Huygens/06/kort-E.html The length of time between the natural noon cycles change,the Equation of Time equalises to variations to 24 hours and that is it.To turn around and then say a 24 hour clock determines natural noon or some irrelevent variation in inclination to the Sun is a product of a silly imagination,again,Piltdown man comes to mind. Anyone who finds substance in these analemmas things is not an astronomer and I do not care how established they have become as a 'fact',even a brief reading of how to determine natural noon and then apply the Equation of Time shopuld be definitive enough. |
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Equation of Time
"Les Desser" wrote in message
... I am preparing a presentation on the Equation of Time and have been trying to find a clear description, preferable with diagrams, of the adjustment due to obliquity. The explanation at the National Maritime Museum http://www.nmm.ac.uk/server/show/conWebDoc.351 only makes sense if you already know the answer The best I could find was the page at http://www.wallingfordclock.talktalk.net/Sidereal%20Time.htm but I still find it inadequate. The example of the bus going down the incline is good to show the slowdown but I cannot find anything appropriate to explain the speeding up. Has anyone seen and better presented explanations? -- Les Desser (The Reply-to address IS valid) I recommend the following web site: http://www.analemma.com/ There is a diagram, possibly what you are looking for, that separates the obliquity and eccentricity effects, at the Royal Observatory web site: http://www.nmm.ac.uk/server/show/conWebDoc.351 Try also wikipedia on both topics. -- Mike Dworetsky (Remove pants sp*mbl*ck to reply) |
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Equation of Time
"Les Desser" wrote in message
... I am preparing a presentation on the Equation of Time and have been trying to find a clear description, preferable with diagrams, of the adjustment due to obliquity. The explanation at the National Maritime Museum http://www.nmm.ac.uk/server/show/conWebDoc.351 only makes sense if you already know the answer The best I could find was the page at http://www.wallingfordclock.talktalk.net/Sidereal%20Time.htm but I still find it inadequate. The example of the bus going down the incline is good to show the slowdown but I cannot find anything appropriate to explain the speeding up. Has anyone seen and better presented explanations? -- Les Desser (The Reply-to address IS valid) Sorry, I realised that I sent in a page you already knew about! Try the diagram on this one. http://www.astronomynotes.com/nakedeye/s9.htm -- Mike Dworetsky (Remove pants sp*mbl*ck to reply) |
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Equation of Time
On Apr 26, 12:04*pm, "Mike Dworetsky"
wrote: "Les Desser" wrote in message ... I am preparing a presentation on the Equation of Time and have been trying to find a clear description, preferable with diagrams, of the adjustment due to obliquity. The explanation at the National Maritime Museum http://www.nmm.ac.uk/server/show/conWebDoc.351 only makes sense if you already know the answer The best I could find was the page at http://www.wallingfordclock.talktalk.net/Sidereal%20Time.htm but I still find it inadequate. The example of the bus going down the incline is good to show the slowdown but I cannot find anything appropriate to explain the speeding up. Has anyone seen and better presented explanations? -- Les Desser (The Reply-to address IS valid) I recommend the following web site: http://www.analemma.com/ There is a diagram, possibly what you are looking for, that separates the obliquity and eccentricity effects, at the Royal Observatory web site: http://www.nmm.ac.uk/server/show/conWebDoc.351 Try also wikipedia on both topics. -- Mike Dworetsky (Remove pants sp*mbl*ck to reply)- Hide quoted text - - Show quoted text - By all means keep the NMM explanation and especially this gem- 'The equation of time due to obliquity (the Earth's tilt) ' "The angle between the planes of the equator and the Earth's orbit around the Sun is called the angle of obliquity. If the Earth's rotation axis was not tilted with respect to its orbit, the apparent motion of the Sun along the the Ecliptic would fall exactly on the equator, covering equal angles along the equator in equal time. " http://www.nmm.ac.uk/server/show/conWebDoc.351 It would be really nicve to have adults who can openly discuss how variations in daylight darkness North and South of the Equator and variations in the natural noon cycles everywhere have the same astronomical root based on the relationship between axial and orbital motions.The reasoning of the NMM where rotational orientation has some effect on Kepler's orbital geometry and the variable noon cycles is ,to put it mildly,as childish as it gets. The shared mechanism which causes no variations in daylight/darkness at the Equator yet variations in the natural noon cycle there requires the addition of an orbital component,one that is already observed by looking at the orbital behavior of Uranus. Just to remind you Mike,in the Piltdown Man episode,it was not the people who were taken in by the hoax or those who built on the ideas that became the most hated and despised ,it was those who knew it was a hoax and kept it going out of personal convenience. even though it had no productive legs.I am willing to concede that it is difficult to extract the orbital component as a seperate motion with respect to the central Sun whereas axial rotation occurs simultaneously as a seperate motion thereby thew whole scheme becomes a modification of heliocentric reasoning.The hoax comes in via the analemma where variable inclination to the Sun was introduced despite the fact that rotational orientation as a consequence of axial rotation keeps the Earth pointing towards pOlaris throughout an annual orbit. I do not know what it takes to shatter this sidereal monster and its destructive effect on the noble Equation of Time scheme but it requires genuine people who do not repeat old falsehoods as you have just done. |
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Equation of Time
oriel36 wrote:
a bunch of gibberish. Who is this clueless dork? A troll? A scientologist? A deranged astrologer? A nitwit necromancer? -- Pd |
#10
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Equation of Time
Pd wrote:
oriel36 wrote: a bunch of gibberish. Who is this clueless dork? A troll? A scientologist? A deranged astrologer? A nitwit necromancer? He's Gerald - a pompous, self important, deluded half-wit who believes he's the only 'real' astronomer in this group. Sort of the Chris Holland of uk.sci.astronomy and sci.astro.amateur but without the blatent homophobia. Jim -- "Well, well. We've come a long way from the Prime Minister's exploding cake." - Adam West, Batman. Find me at http://www.UrsaMinorBeta.co.uk |
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