[meteorite-list] Dog Days and Sirius: was "List is Quiet"

[Sterling K. Webb]

Bernd, List

Well, yes, not every Egyptian civil calendrical year,
but every true sidereal solar year. However, the Egyptians
did not rely on a 12-months-of-30-days-each calendar,
but inserted a block of 5 days "outside of time" (hence
very calm and peaceful) to create a 365-day solar year
for civil purposes.

In widespread use was also a lunar calendar of 13
months of 28 days each for a 364-day year which then
required the insertion on only one holiday day "outside
of time" to achieve a 365-day year for religious purposes.
Lunar calendars are still in widespread use as the Jewish
and Muslim calendars of today.

It's easy to see that a 365-day year will get one day out
every four years, and that in 4 times 365 years (1460
years) the gears of the calendar wheel will reset things
again to match earth and sky synchronism.

This 1460 year cycle is called the Sothic cycle. However,
the Egyptians knew that if you timed from one heliacal
rising of Sirius to the next, you were timing a true solar
sidereal year of 365.25636... days.

A-Ha! you say, the precession of the equinoxes would soon
ruin that correspondence, but Sirius is a nearby star with
a proper motion opposite to and roughly the magnitude
of the precession movement, therefore Sirius appears to
be "immune" to the precession of the equinoxes in so far
as can be detected without instrumented astronometry.

To the Egyptians, it appeared as "fixed point," the only
fixed point in the heavens. This cycle was only discovered
in Egyptian texts in 1904 and there is argument as to
whether the first Sothic cycle began July 19, 4241 BC
or July 19, 2781 BC.

The Deccan calendar of 360 days was divided into 5-day
weeks, the addition of one week created the civil year.
The number of days in the four years it took the civil
calendar to slip one day is 1460 + 1 = 1461 days to even
things up again. And of course, 1460 equals the number
of years in the Sothic cycle. Equally the Deccan calendar
date was 4 x 5 +1 = 21 days out every four years.

Thus, it was possible to calculate the days of offset between
the Deccan, civil and Sothic calendars for any date with simple
calculations. Very handy and practical, as the Egyptians
always were. The Romans would neaten things up further,
being more practical than the Egyptians, with the leap year
and 500 years ago we Westerners would fiddle with the leap
year rules to make it fit even better, being more practical than
Romans...

The tradition of the "extra" five days entered mythology as the
"Halcyon Days," but everybody will have to Google that one up
themselves.


Sterling K. Webb
-----------------------------------------------------------------------------------------
----- Original Message ----- 
From: <bernd.pauli at paulinet.de>
To: <Meteorite-list at meteoritecentral.com>
Sent: Sunday, August 01, 2010 4:31 PM
Subject: [meteorite-list] Dog Days and Sirius: was "List is Quiet"


Sterling wrote:

"It is the *heliacal rising of Sirius*, the *Dog Star*, which achieved 
conjunction
with the Sun on July 31, but won't be briefly visible on the eastern 
horizon at dawn
until August 7th or so...It was the basis of the Egyptian calendar, for 
the appearance
of Sirius marked the start of the rising of the Nile to flood. 
Anciently, the heliacal
rising of Sirius at that time and latitude happened on July 23 every 
year."


Hi Sterling and List,

As for the heliacal rising of Sirius, I totally agree. That's why the 
first sighting of
the brilliant star Sirius in the morning sky (shortly before sunrise) 
was regarded as the
true New Year's Day by the ancient Egyptians.

Unfortunately "not every year", at least for the ancient Egyptians 
because they used
a civil year of 365 days instead of 365 ¼ days. They did not use our 
leap-year so that
after about 120 years the civil year would be a whole month in advance 
of the astro-
nomical year. Because of this defect in the civil year, it sometimes 
happened that the
real summer fell in the winter of the civil calendar, and vice versa.

Reference:

GARDINER A. (1994) Egyptian Grammar (Third Edition, Revised, pp. 
204-205).


Best wishes,

Bernd

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