Draco...Sky serpents.

The moon is inclined by about 5 degrees to the ecliptic, and the moon travels a full circle around the earth each month.

So the moon crosses the ecliptic twice each month.
The Moon takes around 27 days to travel all the way down and up again.

The position in the sky where the moon crosses the ecliptic is a 'node'.

Here is a picture from my files, with  'Babylonian' terms.

MURAB means node.
NIM is moon's maximum angular distance each month.
SIG is moon's minimum angular height each month.





Even though each crossing is a node, the term node is often used to specify two particular nodes a year.

The important nodes occur when the moon is crossing in front of the sun. These nodes are  more significant because there may be a solar eclipse.

But terms such as Caput Draconis in Virgo seem to hint that equinox eclipses are somehow more significant than others. The significance may well be the effect these equinox nodes have on the moon's positions relative to the ecliptic for the rest of the year.

Eclipses in 2015

  • March 20: Total solar eclipse
  • April 4: Total lunar eclipse
  • September 13: Partial solar eclipse
  • September 28: Total lunar eclipse


This year, the sun was eclipsed by the moon at the spring equinox.
The moon was descending from the ecliptic, to below it, reaching its lowest point in relation to the ecliptic for that month about a week latter.

This September, the moon will be ascending as it crosses the ecliptic (the node) closest to the equinox, but the node does not occur on the equinox.

This rule is more useful:
A solar eclipse always takes place within one fortnight of any lunar eclipse

Clearly there is a connection between the Draconitic period and eclipses, but is the Draco the constellation Draco, or does Draco mean any one of four! sky snakes?

There are four sky-serpents:
  1. Draco - coiled around the ecliptic pole.
  2. Hydra.
  3. The snake held by Ophiuchus 
  4. And Cetus, from which the river Eridanus flows.


Draco.
Even though William Orcott has put the word Nodus on his drawing of Draco, I'm still none the wiser!

Hydra.
In 2500 BC, the equinox is situated in Taurus and the serpent Hydra straddles the equator.


Unfortunately Hydra and the ecliptic will never coincide, so the moon will never be above the ecliptic and on the head of  Hydra.

The sun rises and travels across the sky at the head of Hydra, around midsummer, and rises and travels with Hydra's tail in September - the autumn equinox takes place in October - so the tail doesn't seem so significant.

But Hydra is always on the equator and so is the sun at the equinox. An eclipsing moon must also be on the equinox to be eclipsed or eclipse...therefore it must be Hydra that shows the likelihood of equinox eclipses, so I guess it must be Hydra and not Draco who swallows the sun and moon.



So the term Draconitic has come from a mix up in snakes?
In Vedic astrology the North Node is refered to as Rahu and the South Node as Ketu, and the moon's undulating course was symbolized by Hydra.

How old is the term?
Hydra's tail doesn't dip below the equator until 2000 BC, so the idea of the sky snake eating the sun and moon must be less than 4500 years old.

There is a reference to the word Draconitic in in Eden's Dedication, of 1574, to Sir Wyllyam Wynter. Eden had written one of the first accounts of America, but more than that about him is hard to find!

By 1574 Hydra no longer lay along the equator. Then as now, Hydra's head is above the equator and its tail well below it.

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