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"The Sothic cycle was based
on what is referred to in
technical jargon as 'the
periodic return of the
heliacal rising of Sirius',
which is the first
appearance of this star
after a seasonal absence,
rising at dawn just ahead of
the sun in the eastern
portion of the sky. In the
case of Sirius the interval
between one such rising and
the next amounts to
exactly 365.25 days - a
mathematical harmonious
figure, uncomplicated by
further decimal points,
which is just twelve minutes
longer that the duration of
the solar year. The curious thing about Sirius is that out of an estimated 2000 stars in the heavens visible to the naked eye it is the only one to rise heliacally at this precise and nicely rounded interval of 365 and a quarter days - a unique product of its 'proper motion' (the speed of its own movement through space) combined with the effects of precession of the equinoxes. Moreover, it is known that the day of the heliacal rising of Sirius - New Year's Day in the Ancient Egyptian calendar - was traditionally calculated at Heliopolis, where the Pyramid Texts were compiled, and announced ahead of time to all the other major temples up and down the Nile." (Hancock) |