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"A fascinating insight into Ireland's ancient burial sites" - Irish Independent
Stone: Calculating the synodic and siderial months
and the exact length of the year
one of the large mounds of the Boyne Valley complex, has become
famous in recent years for its huge array of 'Neolithic art'.
The site has been said to contain over a quarter of all known
art from this period in Europe, and now that excavations are winding
up at the site after nearly 40 years, a full inventory of the
art has been made.
a question must be asked of this amazing written record, which
comes to us from as as far back as 3,300BC, at which time the
construction of Knowth began. The question is this - what does
the art mean? Is it really art, whether abstract forms, or symbolism
- or is it a mixture of abstract representations and drawings
of real objects. Could the carvings be representative of something
else, something arcane and mysterious, or even astronomical?
believe that much of Knowth's art can be explained properly when
viewed from an astronomical viewpoint. In the context of the Boyne
Valley complex of sites, Knowth begs to be interpreted fully and
properly, and in my opinion that process must begin with astronomy.
moon symbols on the Knowth Lunar Stone.
casual visitor will see that Knowth's stones are covered with a
vast array of symbols. Many of these symbols are repeated, with
common forms including circles, spirals, curves, zig-zags, semi-circles,
crescents, lines, lozenges and other features. The casual visitor
will also notice that many of these forms appear present an astronomical
theme, revealing an interest in the heavens.
Brennan has suggested that this kerbstone at Knowth was
used for making a 27-day lunar calculations. Although he's on
the right track, I believe it goes much further, and reveals
a complex system of moon counting which shows that the ancient
stone builders were competent astronomers, and used it to tell
the length of the year. The secret of the stone lies in the
way the symbols are counted. When you know the count, you know
the meaning of the stone.
lesson on how to solve this 5,300-year-old puzzle begins with
trying to classify the elements so that they can be identified
as specific symbols and representations. We can classify the
markings into easy-to-remember groupings: circles, crescents,
waves, a spiral and a line. With this system of classification,
we can now explain the symbols, how they were counted and, what
the 'secret' knowledge contained on the stone really is. Then
the symbols will be seen as parts of a unified whole.
my opinion, the symbols can be interpreted as follows: the crescent
shapes are early and late phases of the moon; the circles are
lunar phases close to full moon, the small spiral with a single
crescent to the right represents the way the count is carried
out, as identified by Martin Brennan; the wavy line represents
numbers of lunations, or months, while the line underneath is
a calibration bar marking a specific number of lunations or
The 27-day count working inwards
The 27-day count outwards
is the count identified by Brennan.
It begins on the extreme right of the stone, working (as shown
in Fig. 1 above) towards the right, a total count of 11 crescents.
Brennan notes that the eighth phase is marked with a line to
indicate a quarter moon. Then the three concentric circles are
added to the count, making a running total of 14. Working backwards
(Fig. 2), we don't count the centre circle because it marks
the turning point of the count, and work outwards, adding another
two circles, total 16, and then the 11 crescents again, totalling
first method of counting reveals the siderial month, the length
of time it takes the Moon to make one complete circuit through
the sky, in other words the time it takes the Moon to return
to the same background stars. It has to be pointed out that
the lunar tropical month is almost exactly the same length as
the siderial month. The difference is so small that it would
take a keen observer over a century to notice!
The 29-day count working inwards
The 29-day lunar count working outwards
second count was not identified by Brennan in his studies of
the stone. It is important to the overall understanding of the
stone, and shows that the level of understanding of the lunar
movements was quite high in such supposedly 'primitive' times.
The count works inwards exactly the same way as the Tropical
Month (27-day) count shown above.
this time, in addition to counting the outer two concentric
circles of the triple circle, the additional double concentric
circle on the far top left of the stone is also counted. So
we have (working inwards) 11 crescents, plus three circles,
total 14, and (working outwards) add two circles, plus another
two circles, total 18, plus the 11 crescents again, totalling
I believe, is the Synodic Lunar Month count, and has been identified
on another great masterpiece, the Calendar
Stone, also at Knowth. While the Siderial Month marks the
Moon's return to the same background stars, the Synodic Month
marks its return to the same phase. Both are important in calculating
the 19-year cycle of the Moon, called the Metonic Cycle. There
are 235 synodic months and 254 siderial months in the Metonic
Cycle. Interestingly, another Irish researcher, Gillies MacBain,
has pointed out that the original total number of kerbstones
around Knowth, 127, is half of 254, or half the number of siderial
lunar months in one Metonic Cycle.
as the exact length of the year in days can be calculated at
the Calendar Stone, so too
can it be done with this Lunar Stone. It involves a simple calculation,
using the stone as a guide, and the result is accurate.
length of the Synodic Lunar Month is 29.5 days, and if we do
as the stone suggests (in the waved line calibrated count of
12) and multiply the synodic period by 12 (in other words 12
lunations), we get 354.37 days, which is 11 days short of a
complete year. One final addition of the 11 crescents will result
in the accurate answer of 365 days.
researchers say the art of the Stone Age was non-representational.
It appears to be very abstract. Some say it cannot be decoded
as having any real meaning. We disagree with that viewpoint.
With enough circumstantial evidence from the interpretation
of the carvings, the sites and the myths, we can put forward
a hypothesis that the Boyne Valley builders were astronomers,
who studied the complex movements of the Moon and planets. So
far, no serious effort has been made to disprove the astronomical
function. Is it the conclusive solution to what was happening
in the Boyne Valley over 5,000 years ago? Maybe not, but it
goes a long way to solving an age-old puzzle - what were these
enigmatic sites about?
pages of interest:
The Calendar Stone - complex
lunar cycle calculations.
sunlight at Knowth - Sunlight in the western passage.
Knowth west - 5,000-year-old megalithic engravings.
Stellar engravings -
the Stone of the Seven Suns at Dowth.
I am, as always, greatly indebted to the masterful astronomer
Charlie Scribner, who has been teaching me the astronomy of
the ancient people over the last year.
to the Knowth page