Re: zodiac lengths
Hi Willy, No worries, Paul and I are totally aware of the differences between constellations of stars and zodiac signs. Also how the precession of the earth influences the position of the Vernal Equinox with respect to the contellations of stars and why my sign is Cancer since my birthday is the 1st of July, although the position of the sun is in the constellation Gemini. Paul, as an artist, made an object which, among other things, enables people to start a discussion about these subjects and I think he has succeed very well! kind regards, Hendrik Hollander -- Analemma zonnewijzers Hendrik Hollander tel: 020 637 43 83 mob: 06 16 462 879 www.analemma.nl www.linkedin.com/in/hendrikhollander -- - Original Message - From: Willy Leenders To: i...@analemma.nl Cc: Bill Gottesman ; sundial@uni-koeln.de ; Paul de Kort Sent: Wednesday, December 23, 2009 1:23 PM Subject: Re: zodiac lengths Hi Hendrik, Paul de Kort is a good artist and he makes exceptional artworks and design. When he involves the sciences astronomy and astrology in his work he hits the wrong ball, however. A sundial is primarily a scientific instrument. The zodiac is a scientifically determined reference system. A constellation of the zodiac is a nonexistent concept. A constellation of stars exists. A zodiac sign exist too. He (and you) confuses the two. And therefore, what he wrote in the brochure about the park in the suburb Saendelft in Zaanstad, is nonsense. He wrote: In several thousand years, the signs of the zodiac are shifted from the position of the Earth and the Sun We also see that the sun is not exactly during one month in a given sign, such as astrology says, deluding us. This varies from sign to sign and a few days to almost one and a half month. And when you are born in early December, you are born under the sign of Ophiuchus, the 13th sign! Astrology and astronomy doesn't have differences in their definition of ecliptic and Vernal Equinox or the location of constellations, zodiac signs, sun, moon and planets in the ecliptic. It is a big misconception that astrologers place their reference system in the stars and do'nt take account of the precession. In the reference system of astrologers the precession is not useful. Stars and constellations do'nt have a place in it. Even if there were no stars the astrology would still have its reference system. It consists of a system of positioning in the the ecliptic, starting from the vernal equinox, divided into 12 equal parts. In this system the position of the sun, moon and planets are projected, as seen from the Earth. Their place in the ecliptic (at a given time, the birth a person for example) and how they interrelate (opposite each other, overlapping, in angles of 150, 120, 90, 60 and 30 degrees) is the underlying pattern that astrologers use. I simplify here, not talking about the Ascendant. I am not talking about the statements by astrologers based on this reference system. That is because it is outside the domain of astronomy. Willy LEENDERS Hasselt in Flanders (Belgium) Visit my website on the sundials in the province of Limburg in Flanders (Belgium) and on worthwhile facts about sundials www.wijzerweb.be Op 23-dec-2009, om 8:45 heeft Analemma zonnewijzers het volgende geschreven: Hi All, This reminds me of a sundial, made by Landscape artist Paul de Kort in Zaanstad/The Netherlands. For dialing usually the zodiac-signs are defined as 30 degrees of the ecliptica. However, the true sun will pass the 12 constellations of the zodiac and also the constellation Ophiuchus (dutch: 'slangedrager'). Paul did make a sundial in which this 13th 'zodiac'-constellation is incorporated. Very nice. for more work of Paul see: www.pauldekort.nl for the sundial, see (page 6): http://www.pauldekort.nl/_backgrounds/getijdenpark%20BROCHURE%20lowres.pdf kind regards, Hendrik Hollander -- Analemma zonnewijzers Hendrik Hollander tel: 020 637 43 83 mob: 06 16 462 879 www.analemma.nl www.linkedin.com/in/hendrikhollander -- lees de disclaimer: www.analemma.nl/maildisclaimer.htm -- - Original Message - From: Bill Gottesman billgottes...@comcast.net To: sundial@uni-koeln.de Sent: Tuesday, December 22, 2009 4:51 PM Subject: Re: zodiac lengths Well done, Frank! -Bill Gottesman Frank King wrote: Dear Thomas, You ask interesting questions and the answers depend slightly on just how precisely you want the model the way the sun goes round the ecliptic. QUESTION 1 ... do [Gemini and Cancer] share *exactly* the same region [on a sundial] or not? I think it is reasonable to DEFINE the 12 regions of the Zodiac as being bounded at 30-degree intervals of solar *longitude*. So Aries extends
Re: zodiac lengths
Hi All, This reminds me of a sundial, made by Landscape artist Paul de Kort in Zaanstad/The Netherlands. For dialing usually the zodiac-signs are defined as 30 degrees of the ecliptica. However, the true sun will pass the 12 constellations of the zodiac and also the constellation Ophiuchus (dutch: 'slangedrager'). Paul did make a sundial in which this 13th 'zodiac'-constellation is incorporated. Very nice. for more work of Paul see: www.pauldekort.nl for the sundial, see (page 6): http://www.pauldekort.nl/_backgrounds/getijdenpark%20BROCHURE%20lowres.pdf kind regards, Hendrik Hollander -- Analemma zonnewijzers Hendrik Hollander tel: 020 637 43 83 mob: 06 16 462 879 www.analemma.nl www.linkedin.com/in/hendrikhollander -- lees de disclaimer: www.analemma.nl/maildisclaimer.htm -- - Original Message - From: Bill Gottesman billgottes...@comcast.net To: sundial@uni-koeln.de Sent: Tuesday, December 22, 2009 4:51 PM Subject: Re: zodiac lengths Well done, Frank! -Bill Gottesman Frank King wrote: Dear Thomas, You ask interesting questions and the answers depend slightly on just how precisely you want the model the way the sun goes round the ecliptic. QUESTION 1 ... do [Gemini and Cancer] share *exactly* the same region [on a sundial] or not? I think it is reasonable to DEFINE the 12 regions of the Zodiac as being bounded at 30-degree intervals of solar *longitude*. So Aries extends from 0 to 30 and so on. On the ecliptic, these 12 regions are distinct and there is no sharing. When you look at the corresponding intervals of solar *declination* you do, as you say, get sharing. In your example: Sign Longitude Declination range range Gemini60 to 90 20.15 to 23.44 Cancer90 to 12023.44 to 20.15 As you see, Gemini and Cancer share the same range of declinations but for Gemini the declination is increasing and for Cancer is decreasing. The answer to your question is YES. So far, this theory has nothing to do with the *shape* of the Earth's orbit but it does assume that the orbit is a plane which is isn't exactly. [Solar latitude hovers around zero but it isn't exactly zero. A REALLY pedantic discussion about whether Gemini and Cancer exactly overlap would take a book!] You then ask about dates. That makes the story very much more complicated but it doesn't stop Gemini and Cancer sharing the same region on a sundial. QUESTION 2 Is the starting date May 20 of one in line with the end-date July 22 of the other or not? You go too fast. Who says the starting date is May 20? It sometimes is and it sometimes isn't. You have to worry about the leap-year cycle and Pope Gregory XIII and his friends. At the moment we are living close to the middle of an almost 200-year run of pure Julian calendar. There are no omitted leap-years between 1904 and 2096 inclusive. This means there is a steady drift in all the dates you are interested in. The starting *declination* of one IS in line with the ending *declination* of the other but when you worry about dates everything becomes harder. The only sensible answer to this second question is NO. It is no because the dates change from year to year. See the answer to Question 4, but first... QUESTION 3 The angles of the ecliptic longitude for the zodiacs are equally distributed (each 30°), [YES that's right] but what about the angles in the earth's orbit around the sun (ellipse)? I don't quite understand this. The ecliptic longitude is the same as the angle of the Earth's orbit round the sun (though you might want to change the sign or add 180 degrees). The answer is THEY ARE THE SAME. QUESTION 4 And what about the dates? They are horrible! I have already said there is a steady drift in the dates but it is worse than that because of the precession of the equinoxes. The answer is THE DATES ARE A MESS and... QUESTION 5 The lengths (in terms of time) of the zodiacs are not equal, but are they constant each year? The answer is UNFORTUNATELY NO. It is easy to see that they are not constant by thinking about this time of year. We have just entered the sign of Capricorn and at this time of year the Earth is closest to the sun. That's good news because it gets winter over quicker. Capricorn doesn't last long! Also, this explains why the lengths are not constant. Unfortunately, there will come a time when we are furthest from the sun in winter. Capricorn will take longer and we could find the northern hemisphere covered in ice. [ There will then be conferences about trying to raise the levels of carbon dioxide :-) ] QUESTION 6 Can anybody give me a better reference than Wikipedia... The best thing you can do is to ask your girlfriend to buy you a copy of Astronomical
Re: Inclining Cone Gnomons
Hi Roger and others, Yep, the point of the cone can indicate the solar time or the solar time including a longitude correction. Reading the time by using the sides of the cone will include the equation of time. The hourlines of the cone-dial are not 100% straight since the equation of time is not 100% symmetric during the year. But differences are small. Keep me posted if you are going to build one. The paper cut-out-version of the cone-dial for North America can be downloaded here if you like: http://www.shop.analemma.nl/paper-cut-outs-_A4_-E_grp_12-1.html kind regards, Hendrik Hollander -- Analemma zonnewijzers Hendrik Hollander tel: 020 637 43 83 mob: 06 16 462 879 www.analemma.nl www.linkedin.com/in/hendrikhollander -- lees de disclaimer: www.analemma.nl/maildisclaimer.htm -- - Original Message - From: Roger Bailey To: John Carmichael ; sund...@rrz.uni-koeln.de ; 'Colby Lamb' ; i...@analemma.nl Sent: Saturday, August 29, 2009 11:37 PM Subject: Re: Inclining Cone Gnomons Hi John, I see where you are coming from but the point of the cone is all that matters for a point projection sundial. The shape of the thing to hold the defined point in space is irrelevant. The distances from the point to the lines are always the same no matter what defines the point. Hendrik's cone are different as the shadows from the sides are what tells the time. Here is my related question? Can the point on the end of the cone tell solar time in Hendrik's cone? It would if the hour lines converged to a point under the cone base that was at the polar gnomon angle to the tip. I really have to design and build one of these to understand it. Perhaps Brian Albinson's Hollander Dial Software available as a digital bonus in Compendium 14-2 can help. Regards, Roger Bailey From: John Carmichael Sent: Saturday, August 29, 2009 1:40 PM To: sund...@rrz.uni-koeln.de ; 'Colby Lamb' ; hend...@analemma.nl Subject: Inclining Cone Gnomons I have been thinking a lot about Colby Lamb’s inclining cone gnomons that he uses on his horizontal sundials, because I love conical gnomons since they have wide pointed easily read and highly visible shadows that look like the pointed hands of a clock. I also just like the look of them. These are what some people call ‘point-in-space’ gnomons or nodi. Others call them ‘nodus based’ sundials. You use the shadow of the tip of a gnomon (located on the polar axis) to tell the time and/or solar declination. But unlike most nodus based sundials which are usually rods or spheres on rods, these are pointed cones. See photos of Colby’s cone gnomon here: http://www.flickr.com/photos/jlcarmichael/3868639918/ and http://www.flickr.com/photos/jlcarmichael/3860044836/ There is no law that says that point-in-space gnomons need to be placed perpendicularly (vertically) on the face. Colby realized this and he places his at an angle. When I asked him why he did this, he said he did it for purely artistic reasons. (Hendick Hollander also uses inclining cone gnomons on his unique award winning Standard Time dials, but he does it because his design requires it for specific gnomonic reasons which I won’t get into here). I also asked Colby if the inclining cone angle was some special angle, but if I understood him correctly, he said that he just picked an angle that looked good. So here is my question… But I’m thinking that there just might be a good gnomonic reason to tilt a cone gnomon on a dial’s like Colby’s because the shadow produced from an inclining cone gnomon might be a better more uniform shadow than that cast by a perpendicular cone, especially if it were angled to the North in line with the polar axis. I did not measure the angle of tilt of Colby’s cone, but it seemed to be smaller than the latitude polar axis angle for Portland. If the cone was angled to match the polar axis, then during the day, the sun would revolve around it in a more uniform way- much more uniform than if the cone were perpendicular to the face (vertical). Does this make sense? John p.s. I’ve discussed with Colby the advantage of blunting the sharp point on cone gnomons because blunting the sharp point increases the time and date readings when the shadow is long. But angling the cone might make them even better! John L. Carmichael Sundial Sculptures 925 E. Foothills Dr. Tucson AZ 85718-4716 USA Tel: 520-6961709 Email: jlcarmich...@comcast.net My Websites: (business) Sundial Sculptures: http://www.sundialsculptures.com (educational) Chinook Trail Sundial: http://advanceassociates.com/Sundials/COSprings/ (educational) Earth Sky Equatorial Sundial: http://advanceassociates.com/Sundials/Earth-Sky_Dial/ (educational) My Painted Wall Sundial: http://www.advanceassociates.com/WallDial (educational) Painted Wall Sundials: http
Re: mathematical formula
Hi All, With the use of a spider sundial, one can easily find the time, indicated by any wrong placed polar sundial. I wrote a small article about the subject. The article will be published in the comming Zonnewijzerkring Bulletin (Dutch Sundial Society) The English version, I have published here: http://www.shop.analemma.nl/wrongly%20placed%20sundials%20%20v1.0.pdf kind regards, Hendrik Hollander The Netherlands -- Analemma zonnewijzers Hendrik Hollander tel: 020 637 43 83 mob: 06 16 462 879 www.analemma.nl www.linkedin.com/in/hendrikhollander -- lees de disclaimer: www.analemma.nl/maildisclaimer.htm -- - Original Message - From: Nani To: sundial@uni-koeln.de Sent: Monday, March 23, 2009 1:04 PM Subject: mathematical formula Dear sundialfriends I want to know if it is possible to develop a mathematical formula to adjust the hours in a sundials made for a different location. (Different hemisphere and different latitude) For example I live in Santa Cruz (Bolivia, South America ) were there are few simple stone sundials. I want to buy beautiful portable sundials made in the world and It would be great if I can adjust them to my local hour. Best regards Adela Morello Lat : 17° 47' 20 S -- --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Homogeneous Analemmatic Sundial
Hi Alex, How nice that you will make this sundial. Keep us posted on the result. I have posted a photo of the closed and open demo I made of this sundial. www.analemma.nl/H_A_Sundial_open.jpg www.analemma.nl/H_A_Sundial_closed.jpg The black strip which keeps the center ring in the north-south position is made of plastic. It is connected to the backside of the sundial. The backside is fixed to the north. The (blue) cirkel with the pivot can be rotated while the blach strip stays fixed to the north. I have posted the artikels on: http://www.shop.analemma.nl/N_frame.html?http://www.shop.analemma.nl/N_home.html (and choose publicatie) You will also find a small movie of the sundial which demostrates the movements. kind regards, Hendrik Hollander - Analemma Zonnewijzers Hendrik J Hollander tel: 020-637 43 83 mobiel 06 16 462 879 [EMAIL PROTECTED] www.analemma.nl nb 52 23' ol 4 57' - lees de maildisclaimer http://www.analemma.nl/maildisclaimer.htm - - Original Message - From: Alex Ware To: sundial@uni-koeln.de Sent: Thursday, October 02, 2008 9:40 PM Subject: Homogeneous Analemmatic Sundial -BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Hi, I've been reading the postings about the homogeneous analemmatic sundial and wish to create one as part of a piece of work for school (admittedly, this is beyond what is asked- I'm just fascinated by these sundials and want to try my hand at a more obscure design). http://www.analemma.nl/homogeneous%20analemmatic%20sundials%20v2.1%20pdf.pdf and http://www.de-zonnewijzerkring.nl/zw-arch/eng-home-zw-08-06.htm I'm having some trouble figuring out how the two trenches and the pivots p and q cause the center ring to be displaced on one dimension only instead of causing the whole ring to rotate. If anyone would be so kind as to point me to any further reading for this type of dial- or help explain how this works (and any other advice) it would be greatly appreciated. Many Thanks, Alex Ware -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.9 (GNU/Linux) Comment: http://getfiregpg.org iEYEARECAAYFAkjlI7UACgkQwTJKNkPO7HTJYgCfW7m5UNMOF2wyDYgXseKkT2JP avwAniyaMBFXOTxj41LAy5zLdY+gdylP =c76/ -END PGP SIGNATURE- -- --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Advice wanted, on 'Analemmatic' sundial orientation
Hi All, very interesting issue, so after all: with a verticle mirror with the right azimut you could turn the famous analemmatic sundial so the the line with the dates is on a path which is not north-south! and the ellips will be alligned with this path looks to me that the issue can be solved after all. One has to investigate if the dimensions of the mirror are realistic and you will need 2 mirrors (or 2 sundials) to cover the whole 24 hours . If the azimut of the path is alpha, the mirror should be at alpha/2, kind regards, Hendrik - Analemma Sundials H J Hollander Fixed +31 20 6374383 Cell +31 616 462 879 [EMAIL PROTECTED] www.analemma.biz lat 52 23' long 4 57' - Original Message - From: Chris Lusby Taylor To: John Carmichael ; [EMAIL PROTECTED] ; [EMAIL PROTECTED] ; sundial@uni-koeln.de Sent: Monday, June 09, 2008 7:38 PM Subject: [SPAM]Re: Advice wanted, on 'Analemmatic' sundial orientation Hi John et al, I thought at first that John Lynes was making a joke, but you could actually do this. If you have a large, fixed, plane mirror you can use the sunlight reflected off it instead of the actual sun. By suitably angling the mirror you can make the sun appear to rotate about any desired axis, not just the earth's axis. So, you can make it appear to rotate about the local vertical, just as it does at the Poles. So, just as at the Poles, an analemmatic sundial using the reflected light will be circular and the gnomon/person will not need to be moved for different seasons. But the numbers will go round anticlockwise, which might cause further objections! The actual angle you'd need is this, I think: take a vertical mirror, facing south, then lean it towards the north at (90+latitude)/2 to the horizontal. For 40 degrees North this makes 65 degrees. So, it's facing the southern sky, as it were. If it were a dialface we'd say it was a direct south reclining dial. Fix it there. Now, put a vertical gnomon close to the bottom centre of the mirror and mark out a perfectly semicircular, equiangular dial around it. It will work from 6am to 6pm throughout the summer. Or, if you want the user to be the gnomon, just mark the spot where they must stand. In the winter months, as John said, the sun's too low in the sky for the reflection to shine on the ground. A mirror of, say, four feet high and eight feet wide would work well. It doesn't have to be 100% perfect optical quality. Users should back up to it to avoid being dazzled, I suggest. I think this is an excellent solution to what at first appeared an impossible brief. Regards Chris - Original Message - From: John Carmichael To: [EMAIL PROTECTED] ; [EMAIL PROTECTED] ; sundial@uni-koeln.de Sent: Monday, June 09, 2008 3:42 PM Subject: RE: Advice wanted, on 'Analemmatic' sundial orientation Hello John L. I’ve never heard of such a sundial and I can’t imagine how it would function. I’m not sure I understand the setup and positioning of the mirror. Is the mirror permanently fastened to the ground or is the mirror moveable? Does the mirror reflect sunlight onto the sundial face, or do you read the sundial by looking at the face’s reflection in the mirror? I just don’t get it. It sure would be helpful to see a drawing if possible. Puzzled in Tucson John C. From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Monday, June 09, 2008 4:08 AM To: [EMAIL PROTECTED]; sundial@uni-koeln.de Subject: RE: Advice wanted, on 'Analemmatic' sundial orientation Dear Alison One expedient, at least in theory, would be to fix a plane mirror, suitably angled in plan to the main driveway and tilted to convert the analemmatic sundial ellipse into a circle. The position of the human gnomon would not vary with the season. The sundial would receive reflected sunlight only on six months of the year, during the summer months, but this is when most visitors would be around. Unfortunately you would need either an enormous mirror or a very modest analemmatic sundial. John Lynes -Original Message-From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Alison ShieldsSent: 03 June 2008 18:57To: [EMAIL PROTECTED]: Advice wanted, on 'Analemmatic' sundial orientation Dear Sundial Experts, I have recently joined this Mailing List, and hope that any memberswill be able to give me some assistance on the following situation. Our local Stately Home (Kentwell Hall, Long Melford, Suffolk) isconsidering installing an Analemmatic sundial, as a new interactiveattraction for visitors - but we are getting 'conflicting' advice,on whether this 'Human Sundial' will work in the way we want it to. We have been in discussion with Modern
Re: Sundial Calculations
Hi Edleyand others, I am not familiar with the Euler and/or Yacas package. I am sure it will work. What I particulair like about Matlab is the matrix approach. In most computer languages, you have to use a lot off for-next loops. In a Matrix based packages as Matlab however, one does not use for -next loops. a loop like for p = 1 to 1000 for q= 1 to 500 a(p,q)= b(p,q) * cos(phi(p,q) next q next p looks in matlab just: A=B.*cos(Phi) where A, B, Phi are matrices of 1000 by 500 elements. One can read it almost like english. If I can help with the algorithm somehow, just let me know, kind regards, Hendrik -Analemma SundialsH J HollanderFixed +31 20 6374383Cell +31 616 462 879[EMAIL PROTECTED]www.analemma.bizlat 52 23' long 4 57' - - Original Message - From: "Edley McKnight" [EMAIL PROTECTED] To: [EMAIL PROTECTED]; "Sundial List" sundial@uni-koeln.de Sent: Friday, October 06, 2006 7:27 PM Subject: Sundial Calculations Dear Hendrik and dialers, In your calculations for your great mean time cone dial you say you use Matlab and Maple. Would a similar math program like Euler and Yacas do as well? Euler and Yacas are freeware, if they could be used for all these great matrix, vector, symbolic calculations, maybe programming in them would be an alternative to a specific sundial program. (I just found them and downloaded them yesterday, so I'm not up to speed on them.) I certainly do thank you for your great mean time dial! Edley McKnight --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
