The Perseids 2018

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The period between August 11th -13th will mark peak activity for the annual Perseid meteor shower.  Like all annual meteor showers the Perseids occurs due to the Earth ploughing through the fine debris left behind by a short period comet, in this case Comet Swift-Tuttle.  Rates of shooting stars could be as high as 60-70 per hour at peak although this figure is under the most favourable of conditions and you’ll likely see less.

This year’s Perseids looks set to be the best shower of the year due to favourable Moon conditions.  A thin crescent Moon will set before the shower gets properly underway providing excellent sky conditions if you’re sufficiently away from urban lighting and (of course) have clear skies.

Even if you don’t see any shooting stars you can always look out for Saturn and Mars in the south, both setting between 2 – 4am in the morning, and appreciate the increasing number of stars popping into view as our subarctic skies gradually darken.

The radiant for the shower is within the constellation Perseus the hero, although you don’t need to look in this direction to see them.  In fact some of the longest fireballs and streaks caught on camera will be picked up looking away from the radiant.

Due to the brightness of skies this far north you’ll want to wait for the Sun to dip as far below the horizon as possible to achieve the most favourable darkness, this means you’ll want to observe as late as possible, ideally close to or after midnight if you can.

 

Shooting stars and meteor showers are one and the same phenomena – fine lumps of material impacting the earth’s atmosphere about 40-60 miles overhead.  These tiny pieces of debris are travelling so fast they superheat when entering the atmosphere and burn up rapidly.  Occasionally a larger piece will impact resembling a spectacular fireball.

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Remember, you don’t have to look directly at the radiant to see a meteor shower, this is just the area of space they’ll originate from.

Observing Meteor Showers

You don’t need any special equipment to view a meteor shower, in fact binoculars or telescopes will just narrow your field of view. Grab a deck chair or a warm blanket, prepare a hot drink, wrap up warm and lay out under the darkest conditions you can find. It’s an excellent activity to do alone or if you have children they’ll love an excuse to get outside for some after dark play.

Put away any lights or bright mobile phones and simply look up and wait. Remember it takes up to 30 minutes for your eyes to fully dark adapt and any exposure to bright lights will start the process all over again. If you need a light red touches are best for preserving your night vision.

Clear skies!

Mars Closest Approach to Earth until 2287

Space Close Mars

 

Today Mars is closer to Earth than it will be for the next 269 years!

The reason for this varying distance is the red planet’s elliptical orbit which alters the distance between the planets each time Earth overtakes Mars. The attached animation below should give you a feel for how this works.

This close proximity means Mars is particularly bright at the moment shining at magnitude 2.8, and will remain so for the next month and a half. In fact Mars is twice as bright as Jupiter at the moment and will be brighter than the gas giant until September 7th.

Weather permitting you can see Mars sitting low in the South after dark, burning like a brilliant red coal. Viewing surface details requires a telescope at a reasonable magnification, currently hampered by the planet wide dust storms raging on the surface of Mars.

Clear skies.

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Total Lunar Eclipse

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This Friday (the 27th of July) the Moon will rise into view in the south east around 9.30pm with an unusual red colour. This is due to a rare phenomena known as total lunar eclipse – when the Earth sits directly between the Moon and the Sun.

But why doesn’t the Moon darken if its light supply is cut off by the Earth, and why will it turn a red colour?

The best way to think about this is to imagine yourself standing on the surface of the Moon as the Earth slowly passes in front of the Sun.

As the disc of the Earth begins to occult the Sun it will start to darken until finally the whole of the Earth sits in front of the Sun. But as this takes place something amazing happens. The Earth’s atmosphere refracts the sunlight into an intense circle of vibrant sunset. It’s this ring of fire around the Earth that illuminates the Moon during totality, giving it an eerie red colour.

This far north between 9.30pm and 10.30pm it’ll still be pretty bright outside but the colour change should still be obvious to see. As the evening progresses the eclipse will become partial and will be almost over by midnight.

Totality for this lunar eclipse will be 103 minutes making it the longest in this century. As my animation below shows we won’t be able to witness the start of this eclipse, only its middle and end.

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Times:

Peak Eclipse 9.21pm
Moonrise (at 57 deg north) 9.35pm
Total eclipse ends 10.13pm
Partial eclipse ends 11.19pm
Eclipse ends 12.28am

Clear skies and happy Moon watching!

 

STFC Support for Astronomy Outreach

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I received some fantastic news this week. The Science and Technology Facilities Council (STFC) are supporting our continued programme of astronomy outreach at Abriachan Forest Trust, via a SPARK award.  The news was published in the BBC Highlands & Islands website here.

STFC council members were impressed with the successful pilot events delivered over the winter, bringing together astronomy, science and culture through the medium of stargazing and storytelling.

The released funds will be invested in observing equipment, landscape astronomy props, and transportation costs to help families without vehicles access future events.  They will also help us deliver another 12 events out at Abriachan over the next year and into 2019.

I’d like to personally thank the following individuals for their formal letters of support on the bid:

Suzann Barr – Learning Coordinator at Abriachan Forest Trust

Martin Hendry – Professor of Gravitational Astrophysics & Cosmology and Head of the School of Physics & Astronomy, University of Glasgow

Steve Owens – Dark Sky Consultant and Author of Stargazing for Dummies.

Elizabeth Barron-Majerik – Project Development Manager, School of Forestry, Science, Maths and Aquaculture, UHI

But most of all thanks to everyone who have attended the Abriachan stargazing sessions so far, during clear and wild weather.   Keep a look out for the future list of events.

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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  – this time Forest Pots made from whipped cream, honey, fruit and oates.  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

Spica and the Precession of the Equinoxes

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A line of the Moon, Jupiter and the bright star Spica can be seen tonight in the S/SW as the Sun sets (try after 11.30pm or later if it’s still too light).  Spica is the brightest star in the constellation Virgo and was the star that helped unearth the 26,000 year cycle known as the Precession of the Equinoxes.

As the story goes a temple in Thebes built around 3000 BC was originally aligned with Spica but the Heliacal sighting was found to have significantly drifted off target some 3200 years later.  This fact was taken up by the Greek astronomer, mathematician and geographer Hipparchus who used this and other data to approximate the precessional cycle time of the heavens (as he saw it) to be over 30,000 years.  An over estimate but a respectable first guess.

Of course we now know the real reason for this apparent cyclic drift of the constellations over long time scales – 25,772 years to be accurate.  A wobble in the earth’s local axis of rotation (see animation below) caused by the gravitational influence of the Moon and Sun on Earth’s equatorial bulge.

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There are a couple of interesting side effects of this dynamic.  Firstly our pole star slowly changes over thousands of years.  In ancient Egyptian times (3000 BC) the northern  pole star was Thuban in the Constellation Draco, and in around 12000 years time the pole star will have moved close to brilliant Vega.

The other effect is that the dates of the original Zodiacal star signs are now completely out of sync with the position of the Sun. A child born today is still designated as a ‘Cancer’ (because the Sun is supposed to be in the constellation Cancer right now).  But the Sun isn’t in Cancer – it’s actually in Taurus.

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.