Re: The meaning of the zodiacal signs.

[Willy Leenders]

Gianni, Your explanation about the meaning of zodiacal signs is very clear and historically interesting. I agree with you that zodiacal signs are the most surveyable indication for date lines on a sundial. There is however a problem by using the classic pictograms. They are not generally known. On sundials it is better to use more figurative pictograms. I can illustrate the chaos and confusion caused by indicating periods of the year with the lines in which the Sun "enters" in the constellations that nowadays  are on the Ecliptic with  "The book of time", a sundial of Jean-Michel Ansel at the Sundial Parc in Genk, Flanders in Belgium. ( See http://www.biol.rug.nl/maes/genk/en/gk-x12-e.htm ) I have always my work cut out in taking away that confusion when I show round visitors in the Sundial Parc. Willy Leenders Hasselt, Flanders in Belgium   Gianni Ferrari wrote:   The meaning ofthe zodiacal signs.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /> Sundial List, even if the zodiacal signs derive from the Babilonian astrology,they were subsequently used to indicate the Longitude of the Sun (measured fromthe vernal point along the Ecliptic). This convention has been followed by the ancient Greek, from the Islamic scientists and from the medieval astronomers during a period of hundreds years, from around the 300 BC till 1400 AD. According to this convention the 12 signs are no more joined to the constellations but only to a value of the Sun’s longitude multiple of 30°. For instance when the Sun enters in Scorpio it meensonly that the Sun’s longitude is equal to 210° Ptolemy, for example, describes in the Almagest an observation thatHipparchus made in 127 BC,and he says that the Sun was in Leo at 8°+7/12°, that is that it had a Longitude of (120° + 8.5833°) = 128.5833°.  In other parts he writesphrases as “the last degree of Taurus was culminating”, etc. Because of the precession of the Equinoxes (from Hipparchus around 29.2°), today no zodiacal sign begins in the constellation with the same name.  For example the equinox of Aries is in Pisces, the summer solstice in Gemini instead that in Cancer, the September equinox in the Virgoinstead that in Libra, etc.  Finally theSun is in the constellation of Ophiucusfrom 5° to 25° of Sagittarius. I think that nowadays the lines of the signs are still drawnin sundials not for astrological reasons, but only to trace the main daily lines (solstices and equinoxes) and to followa tradition that has hundreds of years. Moreover in the 12 days in whichthe signs “begin” the Sunhas only 7 different values of declination and therefore the lines that are drawn on a sundial are only 7, well spaced and arrangedalmost symmetrically. As Fer de Vries writes, they arevery easily legible. If we wanted to draw the lines corresponding to the beginning of the 12 months we would not only have more lines but these would have put in enough confused way. At the end, thelines in which the Sun “enters” in the 13 constellations that nowadaysare on the Ecliptic, are even more chaotic and confused : for example the Sun remains in Virgo for around 45 days while in Scorpio only for a week. Best Gianni Ferrari 44° 39' N      10° 55' E Mailto : [EMAIL PROTECTED]