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Re: Ecliptic, zodiac and history
From: John Huth
Date: 2010 Dec 11, 09:23 -0500
From: John Huth
Date: 2010 Dec 11, 09:23 -0500
The easiest way to do it is to chart the sunrise/sunset location against markers lying on the horizon. Historically, you can find things like the Hopi sun calendar, or orientation of grave barrows in northern Europe. The discussion of astronomical alignments of places like Stonehenge seem to still be in flux, but there are pointers to the path of the ecliptic. With decent markers on the horizon, you can see when the Sun appears to "stand still" against the markers at the solstices. (Sostice = "sun stop")
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Keeping up with the grind
A more interesting issue is the knowledge of cycles of the Moon - the Saros cycle for example. People would have to wait 18+ years to accumulate information from one eclipse to the next (18 years, 11.3 days between lunar eclipses). Half a year is nothing compared to figuring out eclipses.
On Sat, Dec 11, 2010 at 1:10 AM, Bill <billyrem42@earthlink.net> wrote:
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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Keeping up with the grind
