| Modulo | Universe

Cosmology, Astronomy and Abstract Mathematics

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Mercury Opportunity


Mercury is only 40% larger than the moon but very difficult to spot

The planet Mercury can be very tricky to observe.  It’s close proximity to the sun means we generally only have brief opportunities to observe it low on the horizon either before or after sunset.

Right now Mercury is approaching maximum eastern elongation (on March 15th to be precise) meaning the planet is up for longer after the sun sets.  The window is still pretty brief with only about 45 mins of useful time to work with after sunset.

Your best chance is to pick a clear evening and head out somewhere with a good unobstructed view to the West.  You don’t need dark skies as the Sun will still be producing a lot of light between 6 and 8pm.

At the moment, and at Highland latitudes, the action starts about 6.30pm just after the Sun sets.  Wait a while then scan the western horizon and you should see Venus first, which will appear brighter.  Use this as a guide for finding Mercury which will sit slightly above it over the next few days.

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6.20pm 14th March 2018, 57 degrees north

The longer you wait after the sunset the easier Mercury will be to see due to darkening skies but also harder due to it moving lower and lower towards the horizon, adding more atmospheric distortion to your views.

If you do see it take a note of its crescent phase.  We almost always see Mercury as a crescent because it would be too close to the sun to see it in a full or new aspect.  One exception to this is during a solar transit when Mercury crosses directly across the disc of the sun.  The next opportunity to witness this will be 11th November 2019, which gives you plenty of time to prepare a solar filter for safe observing of the solar disc.  Happy planet hunting meanwhile.

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Transits reveal the true scale of the Sun

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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


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


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

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Super Blue Blood Moon


So what’s a ‘Super Blue Blood Moon’?

It’s a combination of three lunar phenomena. A blue moon is when two full moons fall in the same calendar month, which isn’t very often (roughly once every 3 years) hence the expression ‘once in a blue moon’. The ‘super’ is because the full moon is occurring at a close approach to earth (formally within 10% of orbital perigee). Finally the blood part indicates there’s also a lunar eclipse, although we won’t witness it from Highland skies.

One of the amazing things when witnessing a lunar eclipse is the blood red colour the moon takes as sunlight refracts around earth’s atmosphere.  This is really an extreme form of earth shine, when we can see the shadowed areas of the moon due to sunlight reflected from earth.  I always like to imagine what a lunar eclipse would look like from the surface of the moon.  As the earth completely obscured the sun you would see a brilliant ring of red light radiating around the black disc of the earth.  The lunar landscape around you would be bathed in an eerie red light.

The blue moon phenomena is interesting when you consider we now use a solar calendar.  Around 40BC Julius Caesar severed the old link with the moon, so that months (or ‘moon-ths’)  no longer coincided with the phases of the moon.

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Lunar Burns Night

Moon between clouds

The star of the evening – a waxing gibbous moon

What do you get if you cross a bright gibbous moon, award winning haggis and a celebration of Scotland’s bard?  A Lunar Burns Night!

This was our fourth stargazing event up at Abriachan and despite somewhat blustery conditions, ended up being loads of fun with a good turnout across all ages.

Haggis handwarmers

Haggis and neep hand warmers

After introductions from the Abriachan crew we kicked off outside with the moon high in the south and making dramatic appearances between fast moving clouds.  After a bit of moon gazing and chat I took everyone back inside the forest classroom for an illustrated talk on the moon – its phases, cycles, observational phenomena and even some discussion on manned moon bases (why the obsession with Mars when we could be building a lovely moon base at much lower cost and risk?).

Stephen presenting Lunar Facts

Presenting my moon talk

After the talk Roni and Suzann called everyone through for Clelland’s dramatic ‘knife wielding’ address to the Haggis, followed by a tasty spread of haggis and neep wraps.  The younger ones then took centre stage as they expertly simulated millions of years of lunar surface evolution – by dropping (never throwing!) metal balls into giant flour trays.  This was followed by 3D moon phases and a competition to see who could guess the real separation between the Earth and Moon.

Clelland addressing the haggis

Addressing the haggis

The evening was topped off up with a haggis drive and Cottar’s tales from Clelland.  I also took a group out for some final moon gazing, and managed to glimpse a few brighter stars between the cloud breaks.

The only disappointment was being unable to set up the video telescope to show folks closeups of the lunar surface.  The sporadic showers and wind made that too challenging on the night, but I don’t think anyone really noticed.


We have more astronomy nights planned at Abriachan before the encroachment of our long summer days.  On March 10th we’re hosting a Star Cluster special under dark sky conditions, followed by a Solar Special on April 14th, where we’ll hopefully be projecting the Sun onto a big screen for all to see.  For details please check Abriachan’s or my own Facebook pages.  As ever thanks to the Abriachan team for helping make these events so fun and welcoming.

Clear skies!


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Sirius Rising


The dog star ‘Sirius’ is now high and visible in winter skies looking South. Draw a line down and left from Orion’s belt and you can’t miss the brightest star in the night sky.

Sirius means ‘scorching’ and was considered a second Sun of sorts to many ancient cultures. Its incredible brightness is due to its close proximity. At only 9 light years away it’s the 5th closest star system to our Sun and a fairly typical hydrogen fusing main sequence star likely to live a long stable life of several billion years.  This is in contrast to short lived giant stars like Rigel and Betelgeuse, which are very distant and appear bright  due to their bloated sizes and massive energy output.

Procyon is sometimes mistaken for Sirius but it rises earlier, hence its name which means ‘before the dog’.  The Arabs told a tale linking Procyon and Sirius as two sisters, who became separated by a great river (the Milky Way) while searching for their missing brother.

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Winter Open Star Clusters

You can see three excellent examples of open star clusters within the Orion and Taurus constellations, all in one convenient direction during winter skies (looking south or south east) and in a rough line drawn out by Orion’s belt.

Open clusters

Start with the Orion nebula (M42), below the three belt stars in Orion.  This star forming region contains a very young open cluster called the Trapezium which is surrounded by glowing clouds of ionised hydrogen gas. You can see this nebula in binoculars but it looks best in a low or medium power telescope eyepiece.

Moving up into the eye of Taurus to the red giant star Aldebaran, we find the Hyades cluster. Aldebaran is like a premonition of the fate that awaits out own sun. A red giant around 7 billion years old, bloated and shuddering in its final gasps before it collapses down to a white dwarf. Shining brightly all around Aldebaran are the members of the Hyades open cluster (although they are much further away) – quite a mature cluster at around 500 millions years old.  Best viewed in binoculars.

And finally moving higher and to the right we find the Pleiades, a lovely jewel box of middle age hot stars (and many less bright members) slowly drifting apart to join the general distribution of stars. When the dinosaurs roamed the earth this cluster would have resembled the Orion nebula – bright and nebulous, its hot infant stars lighting up the surrounding hydrogen gas clouds.

Clear skies.

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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.


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.


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.