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I am guessing when I get an answer to my question, I'll slap myself on
the forehead and utter, "Of course." But here goes.

I look at star charts and planispheres with the current ecliptic--the
path of the sun through the stars--neatly added. I take it for granted
that if I could see the stars and the Sun simultaneously that is the
relationship I would see. Easy to confirm with an almanac and spherical
trig.

The zodiac signs--a form of right ascension or SHA--lie along the
ecliptic as opposed to the celestial equator. The zodiac etc. have been
around for about 3000 years, spanning the Sumerian's lunar calendar, the
Babylonians, and the sexagesimal system. The shift of the First Point of
Aries to its present location on the celestial equator also appears to
indicate a long history of ecliptic knowledge.

My question, how the heck did they figure out the ecliptic so long ago?
  No pi, no trig.  A viewer would have to wait half a year to see the
star pattern that would have that day's Sun superimposed on it. Yes?  A
lunar calendar with 12 cycles a year and a leap month every three years
would not be a big help.

Bill B.

   

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