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Cosmology, Astronomy and Abstract Mathematics


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Mercury at Maximum Elongation

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Heavily cratered Mercury

If you have flat and unobstructed views towards the south west there’s a chance of observing one of the most elusive planets this evening – Mercury.

Mercury is hard to see because it orbits so close to the sun, meaning it’s usually lost in the glare of our parent star.

However the planet is currently at its maximum eastern elongation from the Sun, so there’s a small window of opportunity to spot Mercury just after sunset low in the south west. Grab a pair of binoculars and see if you get lucky.

For us high northern latitude observers it’s a tough ask due to the currently flat orientation of the ecliptic, but even if you don’t see Mercury you should catch Saturn sitting just a little higher on the horizon.

Mercury goes through several peak elongations from east to west during a year, providing alternating opportunities to see the planet in pre-dawn or evening skies

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Maximum eastern elongation

Despite being closest to the sun, Mercury isn’t the planet with the highest temperatures – that prize goes to Venus with its thick carbon dioxide cloud base.  This is because Mercury has no atmosphere to trap or distribute heat.  If you were able to stand on Mercury, your daytime temperatures would be a blistering 427C.  However, if you hid in the shadow of a large crater or travelled into the dark half of Mercury, temperatures would plummet to a freezing -173C!  Again, due to a lack of atmosphere to smooth out the temperature extremes.


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Stargazing at Balloch Brownies

I had the great pleasure of helping the 2nd Balloch Brownies gain their Stargazers badge this evening.  Brownie leader Gaener Rodger wanted an astronomer to lead the girls through basic constellations and star navigating, but I came prepared for both outdoor and indoor activities in the event of poor skies.

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A captive and very excitable audience!

The location for stargazing was next to the Balloch hall (beside Balloch Primary) which has some fairly bright street lights nearby.  Thankfully the skies were clear enough to make out the main constellations once we’d shifted our location to the gable end of the hall, away from the worse offending lights.

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The plough or dipper is one of the best asterisms to orientate an audience and begin a stargazing tour with.  Ursa Major is also home to dozens of interesting stars and deep sky objects.

The stargazing tour lasted about 30 mins and covered the following:

  • Ursa Major and the big dipper pointers stars
  • Polaris and circumpolar constellations
  • The story of Callisto and Arkos (The greater and lesser bears)
  • Cassiopeia and the story of Queen Cassiopeia and Cepheus
  • The great square of Pegasus and the legend of Perseus
  • The Northern Cross (Cygnus)
  • Stellar physics on the differences between the stars Vega, Deneb and our Sun

Although it was quite a large group (around 20 brownies), I was amazed at the number of really interesting questions the girls kept throwing at me – what’s a light year,  what causes a supernova, how many stars are there?  The science behind the stars seems to really engage the minds and imaginations of children.

After stargazing we headed back inside for some of the indoor activities I’d prepared.  These included:

  • Demonstrating Moon phases using spheres on sticks and bright head torches
  • A competition to guess the distance from the moon to the earth (using scale ‘chocolate’ models)
  • Mars and Moon cratering using trays of flower, coca powder and lots of marbles!
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Laying down the lunar soil

The latter experiment was messy but well worth the effort, and was a good opportunity to discuss planetary evolution – why the moon and inner planets have such clear cratering and what it tells us about their age and history.

All in all it was a great evening and more importantly the Brownies seemed to have a fantastic time.

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Discussing the impact craters


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Cairngorm Stargazing Weekend and the Ghoul Star ‘Algol’

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Algol in Perseus – an eclipsing binary star system

I had a great two nights of stargazing with guests at the Grant Arms Hotel in Grantown-on-Spey this weekend.  The Grant Arms is a 3 star gold hotel located on the main street of Grantown-on-Spey, and a superb base for adventure holidays within the Cairngorms National Park.  The Cairngorms also doubles as one of Scotland’s best stargazing locations due to the area’s superb dark skies and elevated position.

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The Grant Arms Hotel in Grantown-on-Spey

After dinner on Friday I met my guests and we travelled out to the remote moors beside Lochindorb, where the skies were ablaze with stars and the Milky Way soared overhead.

Most of the main autumn constellations were on display with only the low western flank of the sky obscured by some distant weather fronts.  Some of my guests had never seen the Milky Way under really dark conditions before and were amazed at the clarity of the galactic disc soaring overhead.

We opted for naked eye and binocular observing and had stunning views of objects like the Pleiades, Hyades and the Andromeda galaxy, which was a clear naked eye target and resolved into a lovely oval haze in binoculars.  Most of the bright stars shone with stunning intensity under these conditions, allowing us to pick out clear colour differences in Orion’s main stars (just rising in the east), and within constellations like Aries and Andromeda.

During my tour I told the story of Algol, the ghoul star in Perseus, and how the ancients were mystified by its queer dimming every few days lasting several hours.  What I didn’t realise was that at that moment we were looking up at Algol during its lowest brightness, which only happens around 3% of the time you care to look at it.

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How to find Algol

The reason for Algol’s periodic dimming is because it has a larger but dimmer companion star in a relatively tight orbit.  Every three days the larger companion occults Algol, reducing the intensity of light reaching an observer.  Algol is therefore classified as an eclipsing binary system.

We headed out into the darkness again on Saturday evening for more fleeting but equaly rewarding observing, with scattered cloud providing tantalising glimpses of clusters and constellations.   Afterwards we packed up and headed back to the Grant Arms for some hot chocolate, and I concluded the weekend with an astronomy presentation in the lecture theatre.

I’d like to thank my guests for being such great company and making it an enjoyable and memorable weekend.  I’ll be operating more Stargazing weekends out of the Grant Arms in the near future so keep a look out for new dates.

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I met some lovely and interesting people during the weekend


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Albireo and Double Stars

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A beautiful exposure of Albireo A and B  by astro-photographer Minos Kritikos

One of the best applications of a good telescope is the viewing of a wide range of double stars. While there are many double stars that can be split in a pair of binoculars, some of the most beautiful examples require more magnification, and that’s where telescopes excel with their narrower fields and greater resolving power.

One of the best double stars to view at northern latitudes lies in the head of the constellation Cygnus the swan – Albireo.

This beautiful indigo and gold double star really dazzles in a telescope eyepiece, and is easily resolved in a small telescope with at least 30x magnification.

The contrast between amber Albireo A and sapphire Albireo B is readily apparent in the above striking image, taken by my friend and astro-photographer Minos Kritikos.

There is still some speculation surrounding whether or not the Albireo pair are gravitationally bound – most evidence suggests they are. If so, their orbital period would be around 75,000 years.

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There are many interesting double stars you can try observing with even a modestly sized telescope – remember that most stars we can see in our galaxy (over 60%) are either double or multiple star systems.  Here’s a list of some other visually pleasing doubles to look out for.

  • Epsilon Lyrae – Lyra (binocular friendly)
  • Polaris – Ursa Minor (high magnification needed)
  • Mitaka – Orion
  • Alpha Capricorni – Capricorn (binocular friendly)
  • Epsilon Pegasi – Pegasus
  • Gamma Delphini – Delphinus
  • Eta Cassiopéia – Cassiopeia (high magnification needed)
  • Gamma Aries – Aries


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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.

 


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Orionids Meteor Shower

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The Orionids meteor shower will peak this month on October 20th, radiating close to the prominent constellation of Orion the hunter.

At Highland latitudes the hunter will rise in the East after 10pm and gain a decent observing altitude around midnight. The radiant for the shower lies just to the left of the hunter and close to the orange supergiant Betelgeuse.

While you wait for shooting stars why not scan below the hunter’s belt with binoculars and marvel at the stunning Orion nebula – one of the best binocular and telescope targets in the night sky.

As ever, you’ll have the best chance of seeing activity if you head to a nice dark site well away from town and city glare.

Be patient, wrap up warm and bring a hot drink to sip while you wait. Good luck and clear skies!


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New Comet Alert!

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Look out for a new bright comet visible in night skies now and for the next couple of weeks.

Comet C/2017 O1 ASAS-SN is presently sweeping its way between the constellations Auriga (The Charioteer) and Perseus (The Hero). Later in Ocober it will move into the boundaries of the faint constellation Camelopardalis.

At magnitude 7 or 8 a good dark site and binoculars will be essential for viewing.

Right now at Highland latitudes, Perseus and Auriga start the evening about 20 degrees above the hoizon in the NE before rotating higher and higher in the sky towards the East beyond midnight. Viewing opportunities will therefore get better as the night progresses.

With a calculated orbital period of 17.000 years this will be a rare viewing opportunity.  Happy hunting.

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