The following text was originally sent to Dr. Arthur Carlson but not to the rest of the sundial list-members on 8/22/96. As Dr. Carlson placed his response to this on the list 8/23/96, I thought that the next exchange(s) would be more intelligible to others if this message were avalable to them.
Begin copy of 8/22/96 message: ____________________________________________________________ Yo Art, Incidentally (a word meaning, here comes a nitpick,)on 8/15/96 @ 06:39 you wrote: >On an astronomical level, the equinox is the *instant* >when the sun lies in the equatorial plane of the earth. My ancient (1964)"Nortons Star Atlas" is informative re actual astronomical practice. I cite part of it as better stated than my own words would be: "...the True or Apparent Equinox, or The Equinox of any date --- moves westward on the Ecliptic 1/7th second of arc every day, but is neverthe- less the most convenient point for the purpose, as the Sun's position in the sky, measured from it, remains practically the same on a given day for thousands of years, by the leap year arrangements of the calendar, though those of the stars slowly change. 'Vernal Equinox,' WHEN USED IN CONNECTION WITH MEASUREMENTS, always means this moving True Equinox, but the LITERAL Vernal (Spring) Equinox is the instant when the Sun's centre actually crosses the Celestial equator." (My upper case in lieu of the italics causa internet.) The Pisces-Aries transition, or First Point of Aries, as also Virgo-Libra in autumn, refer to 12 "Sign" sectors, each 30 degrees long, into which the Ecliptic is divided. These Sign labels do not relate to the similarly named actual constellations. The Pisces-Aries point is therefor, 180 deg away from the Vernal Equinox. In these ecliptic coordinates used, the sun has a very small latitude (very roughly 0.005 deg) for the 1997 Autumnal Equinox which results (due to the low rate of change) in a difference of a bit over 20 mins. of time earlier for zero declination, than for the event if measured per the above convention as used for almanacs, etc.. Cheers, Bill. -- To study,.. and study,....and to perish. Anonymus Bosh ___________________________________________________________ End of Copy W. Maddux
