82 AUSTRALIAN SKY & TELESCOPE May | June 2017
THE LAST PREHISTORICstanding
stonecirclewaserectedintheBritishIsles
thousandsofyearsago.SowhywouldI,
an amateur astronomer, want to build
onenow?Forthat’swhatIdidrecently
with the support of fellow members of
my local astronomical society.
Oneofourclub’sgoalsistohelp
anyoneinterestedingainingabetter
understanding of the universe we live
in.Whynotstartwiththecloseststar
toEarth,ourveryownSun?What
betterwaytointroduceyoungpeopleto
astronomythantoshowthemfirsthand
howsomeancientpeoplesusedtheSun
asacalendar?
Threeyearsagooursocietyreceiveda
gift of 14 hectares of flat terrain. With
itsdarkskiesandeasyaccess,thesite
isidealforuseasanastronomypark.
When complete, the park will host
several astronomy domes, camping and
picnickingfacilitiesandthestanding-
stone calendar.
WhenIfirstexploredon-sitethe
feasibilityofbuildingthecalendar—it
wasacold,gustyautumnmorning
beforesunrise—myminddrifted
back to distant ancestors from the RUSS ERGANBRIGHTLet the stones stand again
An astronomy club has built a Neolithic-style solar observatory.
British Isles who perhaps made use of a
standing-stone observatory much like
the one I planned to construct. Who
were those people? How did they live?
What mythology did they create around
what they saw in the sky? Only their
stones remain to suggest answers.
The stone calendar took two years to
design, plan and build. In keeping with
the low-tech nature of construction
in Neolithic times, we made all
astronomical observations with the
unaided eye, and we measured distances
with a simple tape measure and roll
of twine. Would this calendar be as
accurate as one made using modern
technology? No. But in its simplicity and
flaws lie its authenticity.
We broke ground in 2015. After
verifying the solar alignments,
we began excavating holes and
manhandling 13 donated limestone
markers, each weighing up to 180
kilograms, into place. Last summer we
installed the final stone, and the site
became a functional solar observatory.
The calendar is approximately 22 metres
in diameter and orientated to true
north. In its centre rises a standingstone surrounded by 12 marker stones
placed roughly 11 metres away from it
around the circle’s perimeter.
By visually aligning the centre stone
with the appropriate marker along the
perimeter, an observer can determine
the equinoxes as well as the winter
and summer solstices. For example, if
you imagine the stone calendar as a
clock seen from above, with 12 o’clock
pointing north, on the winter solstice
the Sun, as viewed from the centre
stone, will rise directly over the “4
o’clock” marker and set directly behind
the “8 o’clock” marker.
How long will this modern-day
version of an archaic stone calendar
stand in that grassy plain and passively
measure out the changing seasons?
A century? A millennium? Only time
holds the answer to that question.
But if just one young person becomes
enriched and motivated by what he or
she observes there, it will have been
worth all the effort. RUSS ERGANBRIGHT, a retired
engineer, can be reached at
[email protected]Sunset over the winter solstice perimeter
stone, with the centre stone in foreground.To see a diagram and learn more about
the standing-stone calendar, go to
https://is.gd/stonecalendar.FOCAL POINT by Russell Erganbright