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Cosmology, Astronomy and Abstract Mathematics


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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.


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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.