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

Solstice Special at Abriachan

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The summer Solstice goes largely unmarked these days. Join me up at Abriachan forest on the longest day to learn all about the Sun’s standstill and why it resonated so deeply with our ancestors.

Join us at Abriachan Forest to celebrate the longest day with a Solstice evening of anicent astronomy and storytelling.

We’ll kick off with a talk from local astronomer Stephen Mackintosh, learning about solar and lunar time keeping, horizon calendars & henges, seasonal constellations and more. Stephen will also give an overview of June’s night skies, including a feast of planetary opportunities and tips on how to get the best views.

We’ll then step back in time and sample the entertainment of our ancestors, as storyteller and countryside ranger Clelland McCallum recounts an ancient tale around the flames of an open campfire.

A warm welcome from the Abriachan Staff with refreshments to toast the Sun’s standstill.  All ages welcome. Tickets are £6 per person. Children 8 years and younger go free.

Booking essential via Eventbrite.  Ticket link here.

Solar Day at Abriachan

We were blessed with a lovely sunny day on Saturday for our day of Solar learning up at Abriachan.  We were fully prepared for indoor activities as forecasts were looking pretty grey.  But as the weekend swung around skies cleared and we ended up seeing plenty of Sun all day.

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A day of fun solar learning

Since conditions were so good we moved everything outside, including the talk I’d prepared which was originally put together on powerpoint.  I demonstrated basic shadow time keeping and direction finding, and how solar eclipses take place using a scale model of the Moon and Earth (with the moon’s orbit inclined at 5 degrees).

Based on our model the Earth and Moon were around 3 meters apart with the former about the size of a large orange.  At this scale the Sun would be 10 meters in diameter and over a mile away!  With this model the relative rarity of total solar eclipses becomes clear (on average one every 18 months).

During the talk we also touched upon:

  • Sun gods and how our ancestors perceived the Sun as a perfect orb with no imperfections
  • The human fear of eclipses
  • The discovery of Sun spots and how they revealed that the Sun is spinning
  • How spectroscopy revealed that our Sun is in fact a star (at very close proximity)
  • Why the Sun is loosing mass – over 4 billion tons of hydrogen per second
  • The ultimate fate of our Sun – how it will eventually flare up as a red giant star before cooling and shrinking down to a white dwarf

After the talk Clelland took over for some fun outdoor activities including a scale walk of the solar system, DIY spectroscopes and solar lasers using big magnifiers.  We also did a fun experiment simulating the colour of the sky and sunsets using milk in water bottles.

In terms of solar viewing, I setup the 200mm with a full objective white light filter, and we also had a Sunspotter, kindly on load from Glasgow Science centre.  Both setups produced clear views of the Sun’s photosphere, but unfortunately there were no sunspots to see.  This isn’t entirely surprising given we’re bang in the middle of the 11 year solar cycle minimum, although large spots can appear suddenly at any time.  We hope to one day invest in a good quality hydrogen alpha filter for these events, as these reveal many more interesting features, like edge prominences and coronal loops.

Overall a fun day of learning with great interaction and questions from the adults and little ones alike.

Next Abriachan Astronomy Dates

I’m excited to be hosting two more astronomy events alongside the Abriachan forest team in March and April 2018.  Details and ticket links below.

Star Cluster Special – March 10th (moved from Feb 10th) 7pm-9pm

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The Hyades and Pleiades Star clusters

Explore the great winter open clusters under moonless dark skies with campfire stories to follow. Outdoor binocular guiding under clear skies. Indoor talk, astronomy activities and virtual guiding in the classroom in the event of poor weather. Refreshments provided.

Ticket link: https://www.eventbrite.co.uk/e/dark-sky-observingwith-a-sta…

Solar Special and the Life of Stars – April 14th 2pm – 4pm

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A typical G-type main sequence star – locals have dubbed this one ‘The Sun’

A Sun special exploring our nearest star and the life of giant stars. Outdoor sun projections and activities, with illustrated talk and refreshments. Suzann even has plans for a solar pizza oven!

Ticket link: https://www.eventbrite.co.uk/e/some-sunny-science-and-the-l…

All stargazing events organised in collaboration with the Abriachan team, astronomer Stephen Mackintosh and learning coordinator Suzann Barr. Campfire tales delivered by forest ranger Clelland.

For group bookings please email: abriachanforest@gmail.com

Lunar Maria

Happy New Year everyone.  There’s been a lovely bright full moon on display over the new year, allowing me to venture out for well lit evening walks, stopping every so often to study the bright lunar disc both unaided and with binoculars.

One very obvious thing you can notice from looking at the moon, especially naked eye, is the contrasting dark and light regions.

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The dark regions are called lunar ‘maria’ which is latin for ‘sea’. These regions are relatively smooth and have a low abundance of craters, which suggests they’re younger than the brighter more heavily cratered regions.

But how can the moon, a dead world with no significant geological activity, have younger regions?

The answer is from giant impacts.

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Imagine a massive asteroid hitting the moon. Not only will it generate a huge crater but the heat from the impact will cause the solid rock underneath to become molten and well up in a huge overflowing lava event. This overflow pours across the surface of the moon a bit like applying fresh plaster to a wall, masking all the old craters and creating what we now see as ‘maria’.

I’ll be talking about this and much more at our special moon night on the 27th Jan out at Abriachan Forest.

Abriachan Forest Trust Gains ‘Milky Way’ Dark Sky Discovery Status

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I was delighted to help Abriachan Forest Trust gain ‘Milky Way’ Dark Sky Discovery status this month after working on a joint nomination with Abriachan’s learning coordinator Suzann Barr.  This is the first site in the Inverness area to be awarded the status and it’ll hopefully attract winter tourism and lots of opportunity for astronomy based public engagement.

The Highlands really are blessed with excellent dark skies – we just need to do more to capitalise on it and perhaps emulate some of the great work that’s been done in the Scottish Borders where the Galloway International Dark Sky Park brings substantial benefits to the local economy.

After the status was formally awarded by Dan Hillier (who leads the Dark Sky Discover network from Edinburgh’s Royal Observatory) I generated a press release which several news bodies picked up, not least BBC Scotland.

Link to  BBC Scotland Article.

The Press and Journal also ran a full page article reproduced below:

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Mesolithic Stargazing at Abriachan

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Stargazing at Abriachan – Photo by Ken Armstrong – Castlehill Photography

A fantastic night of stargazing was had at Abriachan community forest last Friday.  The night was dubbed ‘Mesolithic Stargazing’ and was delivered as part of the Highland Archaeology Festival.

Abriachan is an excellent location for dark sky observing, being both well elevated in the high moors above the Great Glen and miles away from urban light pollution.  Its southern skies are particularly stunning.

Interest in the event far exceeded expectations, with a Facebook event erected in August achieving a shared reach of over 35,000 people!  The Sky at Night magazine even got in touch, wishing to highlight the event in the ‘What’s On’ section of the print magazine.   Because of this, a late request for email bookings had to be enforced by Abriachan to control numbers.  This left lots of folks disappointed but ultimately ensured the event ran smoothly.

There were two elements to the evening which people could move between – stargazing and mesolithic campfire stories.  I was set up to host the stargazing component out in the open above the forest classroom, while ranger Clelland built a hearty fire in the woods for camp fire tales.  Meanwhile, Suzann and the Abriachan team prepared the site and classroom, marking out paths with glow-sticks to help people negotiate safely in the dark.  They also readied hot drinks, soup and snacks to serve from the Camanachd Cabin beside the classroom.

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Mesmerising colours – Photo by Ken Armstrong – Castlehill Photography

Around 7pm folks started arriving, just as an ominous bank of clouds rolled in.  I needed some extra time to decide if the stargazing would go ahead at this point, so Suzann helpfully escorted the first group of folks down to the campfire for stories.  Meanwhile, lots more people were arriving and a call had to be made soon on whether to abandon the stargazing, and instead present an indoor talk I’d prepared on ‘Ancient Astronomy’.

Thankfully the shifting skies soon made that decision easy.  The clouds began melting away revealing a lovely evening sky peppered with brighter stars.  By the time I escorted my first group to the appointed observing spot the skies were ablaze with stars, and a beautiful Milky Way soared overhead.  After that, conditions got better and better, and to top it all off a mesmerising display of northern lights materialised, distracting everyone from the stargazing as it ebbed and rippled high in the northern sky.

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The Summer Triangle and the Cygnus Rift, captured by photographer Claire Rehr

In rough order, the stargazing tour covered the following:

  • Ursa Major and the Big Dipper asterism
  • Ancient navigation and time keeping using Polaris and circumpolar constellations
  • Properties of Polaris
  • Cassiopeia – the 1572 Tyco Brahe supernova
  • Perseus – the Merfak group, the double cluster and the ghoul star Algol
  • Andromeda – the stunning M31 galaxy.
  • The story of Perseus, Andromeda, Pegasus and the sea monster Cetus
  • The summer triangle – Vega, Deneb and Altair
  • Cygnus – the galactic disk, the Cygnus rift and the Kepler exoplanet survey
  • Lyra – Vega and the double double
  • The unique properties of the blue-white giant Vega
  • Delphinus and Sagitta – the coat hanger asterism
  • Meteor storms and large impactors

The tour was largely naked eye and with binoculars.  I had hoped to get some telescope time in with the 200mm auto tracker, but the groups were too large to make that a practical option.  However, some folks who stayed behind after the tours did see some pleasing views of Andromeda and the double cluster in the eyepiece.

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More stunning aurora, captured by photographer Claire Rehr

Overall the evening was a big success with lots of positive feedback.  The addition of a stunning display of northern lights made the experience all the more memorable.  By all accounts the story telling was very well received too, with Clelland recounting a Celtic tale about Ursa Major, including the ghoul star ‘Algol’ in Perseus, which we’d surveyed earlier in the sky tour.

A followup event is planned for November 18th.  Please check the Facebook site for details.