Happy Winter Solstice

Today the northern hemisphere of the Earth is maximally inclined away from the Sun, producing the shortest day. This is due to the axial tilt of the Earth, driving the seasons as we hurtle around our home star each year.

From here on, imperceptibly at first, our days grow longer in the northern hemisphere and shorter in the southern hemisphere.

This change in daylight is like a trigonometric Sine wave and will accelerate as winter advances, reaching its greatest rate of change near the Spring equinox in March.

The image I’ve shared was taken from inside one of the the passage cairns at Clava a few years ago on Dec 21st, a site with claimed mid winter significance. Sure enough light flooded into the back of the cairn via the south western aligned passage.

The truth is we don’t really know the real significance of these structures, and are left to speculate, sometimes more wildly than the evidence deserves. But it’s fun and captivating to imagine what could well have been ancient connections linking landscape, culture and the heavens above.

Seasons greetings everyone.

The Astronomy of Ancient Places (Livestream talk)

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In view of recent developments my contribution to this years Inverness Science Festival will be a free live streamed talk.  Please visit my Highland Astronomy facebook page for more details:

Astronomer Stephen Mackintosh will take you back in time to discover how our distant ancestors used the Sun, Moon and stars to track the progress of time and the seasons. Looking at ancient monuments connected to the night sky, we’ll go on a tour of Egypt, Central America, southern England and back home to Scotland where some of the finest concentrations of neolithic structures exist anywhere in Europe, not least the wonderful Clava Cairns. Plus advice on sky watching and naked eye observing you can put into practice yourself.

Note: this event is free and will be live streamed online as part of the Inverness Science Festival’s adjusted programme.

Stephen Mackintosh’s blog: modulouniverse.com
Image by Callanish Digital Design: callanishdigitaldesign.com

Marking the Solstice

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The setting Solstice Sun – Image courtesy of Abriachan Forest Trust

We had a fantastic summer solstice event up at Abriachan last Thursday evening.  Despite being a mid week evening the event sold out and we had a lovely gathering of people joining us to learn all about the solstice and why it was such an important cultural and astronomical marker.

The evening started with a round of Sunset Mocktails, crafted by my wife Judith from a wild fruit concentrate, orange juice and lemonade.  We were also blessed with a lovely sunny evening and enough wind to keep the midges at bay, allowing everyone to mingle and chat outdoors.

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A Sunset Mocktail

After waiting for some late arrivals I took the adults and older children into the forest classroom for a talk on the solstice and ancient astronomy, whilst the very young children made flower crowns and Sun mandalas in the greenhouse.

To kick things off I presented a quick ‘what’s up’ guide to June’s night skies and the fantastic collection of planets visible over the next few months – Jupiter, Saturn, Mars and Vesta, the second largest body in the main asteroid belt.

The talk then progressed onto the observational dynamics of the Sun in the sky – its elevation, setting and rising points and the resulting shape the Sun will make when photographed at the same time each day for a year – an Analemma.  We then looked at the reason behind these dynamics (the Earth’s 23.5 degree tilt) and compared our seasons to that of Mars, a world whose 25 degree tilt and highly eccentric orbit produces some of the most extreme seasonal changes of all the planets.

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This is the shape the Sun makes in the sky if photographed at the same time over a year.  Ancient people probably knew about this by instead looking at the shadow projected from a straight object.  Was this shape tied to the mathematical symbol for infinity, or even Pictish and Celtic knot art?

From there we covered the construction of a primitive wooden solar calendar and looked at various examples of ancient solar markers from across the word, including many of Scotland’s mid winter aligned covered cairns (for example Clava Cairns in Culloden).

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The cairns in Clava have an obvious mid winter sunset alignment and an interesting array of  surrounding stones which raise in elevation towards the South West.

After the talk we broke for more refreshments and it was then over to Clelland for the rest of the evening.

Clelland stared off with a walk and talk describing the various plants which were important during the mid summer months and how the Sun was believed to lend magical power to the plant lore in olden times – boosting their healing and nutritional value.  Everyone then gathered in the green shelter around an open fire as Clelland told a local story to illustrate the way fact and legend are intermingled and passed down through the generations.

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As a final gesture towards the setting sun on the longest day folks were asked to write a wish on paper, set it alight and place it in the loch – a reenactment of an old Scots tradition of sending your wishes tumbling into the loch in burning balls of hay!

Feedback on the event has been great and we’ll almost certainly do something again next year. A big thanks as ever to Suzann, Ronnie and the staff at Abriachan for helping make the event so successful.

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Making a Solstice wish