The natural Navigation: The Right Course, Naturally

I went for a walk in the South Downs yesterday afternoon. The air was cold, there were still chunks of ice lining the north-facing side of chalk ruts in the path. The sun was up for the first part of the walk and made direction-finding easy. When it fell below the hills to my southwest it gave different opportunities. One of my favourite dusk techniques is to use the light reflections of cloud edges to gauge where the sun must be behind higher ground. This photograph from 4.30pm yesterday shows this effect quite clearly. The sun is reaching the far ground, trees and clouds, but it does not light the clouds equally. The bright edges act almost as a parabola, pointing the way back to a now invisible sun.

The picture was taken looking northeast. The very perceptive will have noticed that there are molehills in the foreground and that…

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…with a little help from the sun.

An interesting article on the BBC website today about the seasonal habits of Puffins.

The most interesting thing other than learning more about the puffins’ whereabouts was the method they used for understanding where the birds were at any one time. Using ‘geolocator tags’ that logged the time of sunrise, sunset the research team were able to deduce their location.

‘The loggers work by measuring light levels, recording when dawn and dusk occurs each day.

With this data, researchers can calculate day length, when midday occurs, and the daily longitudinal and latitudinal co-ordinates for the individual bird.’

The tags also detected when the birds’ feet were wet, the hope being that this would give information about when the birds were airborne, but the puffins foxed the researchers here: they like to tuck their feet up into their plumage when asleep. Their feet…

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Nothing tickles me more than stumbling across an obscure reference to an arcane relationship between humans and the natural world. The tickling sensation is particularly acute when the reference is historic and it concerns celestial objects.

On New Year’s holiday in Strathconon in the Scottish Highlands I waded merrily into Simon Schama’s, ‘Citizens, A Chronicle of the French Revolution‘. The subject matter was rich enough and when generously layered with Mr Schama’s oppulent language it was a feast worthy of the Christmas period.

Following on shortly from the sentence, ‘The arrival of the Palais-Royal as a quotidian carnival of the appetites drastically altered all that.’, I learnt that the palace forecourt used to be home to cannon that would go off at noon each day when the sun’s rays passed through a carefully aligned lens to ignite the fuse.

I lay awake after reading that, thinking of how one…

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…and he was high in the sky, which reminded me of one of the simplest and most beautiful of natural navigational celestial techiques. Orion is a great help in finding East or West, but there is a method for finding direction that works even if you have no idea what object you are looking at in the sky. It takes time to apply accurately, but it can be used anywhere in the world and applies to all the stars, the moon, the sun and all the planets – even if you have no idea which one you are looking at.

The moment a celestial object reaches its highest point in the sky it will be due north or south. Simples! As those meerkats like to say. Well, the principle is beautifully simple, but the practice is a bit more involved. Hence the use of shadow sticks, and sextants for that…

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On holiday I did try very hard not to think too much about navigation, but wherever I am I cannot resist checking that the sun is behaving itself appropriately considering my latitude and the season. At 7 degrees north, Phuket is in the northern hemisphere and the tropics and because the sun is now well south of the equator the short midday shadow is cast towards the north. Nearer June this same pencil would cast a shadow in the opposite direction at midday, to the south.

This photo was actually taken eleven minutes after local midday, which is logical since it was taken in the west of Phuket and Phuket itself is in the west of the country, about 2 degrees west of Bangkok. The sun will be at its highest point over Phuket about eight minutes after it has reached its highest point when viewed from Bangkok.

At eighteen minutes past ten tonight, neither the north pole nor the south will be pointing towards or away from the sun and the sun will be overhead the equator. It is the autumnal equinox and the sun will spend the next six months overhead the southern hemisphere. During this time it will rise south of east and set south of west.

To celebrate this I headed up to one of my favourite spots last night, Halnaker Windmill, and took this photo. The clouds and light were doing extraordinary things, one of which I am still investigating and will hopefully be able to reveal more about.

Another cracking dawn. There were four Roe deer in our neighbouring field, but sadly they scarpered before I got to my camera. I don’t actually have a brilliant lens for wildlife, so you have been spared a photo of four brown smudges in a brown field.

Only a few days of this solar season left, the autumnal equinox is on 22 September. This means that in the UK there are only four more days when the sun will have any north in it at all for another six months. At times like this, close to the equinox, the point on the horizon that the sun rises changes by more each day than at any other time in the year.

Regular blog readers will know that I am a bit of a fan of Robert Pirsig’s book, ‘Zen and the Art of Motorcycle Maintenance‘. I’m just about to finish the sequel, ‘Lila‘, which is also a bit of a positive mind-bender (that is if you have some alternative views, and possibly a negative one if you consider yourself a conformist. Come to think of it, a conformist wouldn’t buy the book, and if they stumbled across it would be unlikely to start it and if they did start it, would be extremely unlikely to finish it.)

Pirsig takes on some massive philosophical beasts in both books, but the freshness of his approach can sometimes be seen best in the way he deals with more simple and natural phenomena. This is his take on the fabled ‘green flash’ of the setting sun,

‘When Phaedrus started to read yachting literature…

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Nice article on the Beeb website about the Saturn equinox. A succinct definiton of ‘equinox’ in the article too:

‘Equinox is the moment when the Sun crosses a planet’s equator, making day and night the same length.’

I forgot to mention that I delivered the manuscript of my book to my publishers, Virgin Books, three weeks ago. It is an exciting moment, a good line in the sand, but far from a terminal one. Work will continue on it until about November probably.

The two pictures above show two sides of the same bridleway signpost on the South Downs Way. The arrows both point east and there is a clue to this in the photos. It is not in the lichen growth, which unusually is quite similar on both sides, but in the colour of the arrows themselves. The blue of the south-facing (but east-pointing!) arrow has been bleached more by the sun. The three main weathering clues are sun, wind and rain. The first will usually be greatest on the southern side, but wind and rain will usually leave their marks more prominently on the southwestern side.