The natural Navigation: The Right Course, Naturally

I love the idea that the moon is trying to tell us where the sun is hiding

In this photograph, which I took a few days ago, the moon is chasing a recently set sun and has begun its own journey down towards the western horizon. You can see the sun’s bright light reflecting vividly off the right-hand, western side of the moon. The light gets brighter towards the edge, until it reaches a burning white at the edge itself.

It is almost as though the moon is trying to say, ‘You’re getting warmer!’

My thanks to everyone who came to my talk last night at the Weald and Downland Museum. What a wonderful place to spend a summer’s evening, I recommend a visit to anyone who has yet to sample its delights.

On a different note, I received a fascinating letter recently from someone who has read the book. They wrote to me with an unusual observation.

I have touched the phenomenon of the ‘green flash’ at sunset in this blog and elsewhere, it is well documented and well heard-of. My correspondent is keen to learn more about something different and since I have been unable to solve the mystery, I promised to publish the extract from his letter here in the hope that a blog reader may be able to offer an insight.

“...My second point is the green flash you mention. My experience was quite different from the quick flash most people seem to…

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I’m just back from giving a short talk at the Royal Institute of Navigation’s Land Conference at the National Physical Laboratory.

I learnt plenty from the other speakers and chats during the breaks. One little gem: the Apollo program nearly lost two astronauts, literally. They were roaming the lunar surface and became temporarily unaware where ‘home’ was. Without a map, compass, GPS or any other instrument there were some tense moments before they found their way back successfully. Definitely an opportunity for some natural navigation training in this niche market, as I was not too shy to point out to the assembled!

Something that makes a walk on the moon more challenging than on earth is that the moon has a much smaller radius and therefore has a more dramatically curved surface, the result being you cannot see nearly as far on the moon as you can on Earth. All other things…

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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.

What a difference an hour makes, I took this photo only one hour later than yesterday’s. Venus was still visible to the naked eye, but being drowned out by the minute as the morning’s twilight becomes dawn itself. Twilight is a hugely important time for celestial navigators as it is the only time that both the stars and horizon are visible. Celestial navigation relies on using a sextant to measure the angle between stars and the horizon. Before the morning twilight the horizon is not visible and after it the stars have disappeared. In the evening it is of course the other way round.

Apologies all blog readers. Firstly the last post wasn’t really fair. The picture quality isn’t good enough to be able to tell that the grasses have been blown in the direction that the picture is being taken or that the distant horizon is bright. The photo was taken a few weeks ago in Wensleydale looking ENE towards the dawn light.

Secondly, I’ve been out of touch longer than hoped for as I’ve been travelling in some nearby, but strangely wild places recently with limited options for internet access, including deepest darkest Brittany and a hut on some rocks in the Channel Islands called Les Ecrehou . Back soon and normal service will resume hopefully!

Sticking with a midsummer theme for another day, I came across this picture today. It was taken in a place called Uttakleiv in northern Norway. The time lapse shows how the sun does get lower, the angle being directly related to the latitude, but at this high latitude even its lowest point is not below the horizon. I was fortunate enough to witness the midnight sun in Kiruna in north Sweden a few years ago, but my photos were a lot less dramatic than this. Something to do with the fact I had flown about ten hours that day in a tiny aircraft. That and the fact that I am not a very good photographer.

It is the morning after the equinox and not a bad one either. The sun rises due east on the equinox, but the daily difference is at its greatest at this time too so we have already moved north of east.

In this picture the horizon is well above sea level because of the hill, so we have to bear in mind that the angle the sun makes to the horizon will be 90 degrees minus our latitude, ie. our colatitude.

There was a typically excellent Horizon documentary on BBC2 last night called, ‘Do You Know What Time It Is?‘ It ranged and veered in a challenging and entertaining way from the Mayans to the sub-atomic. I hadn’t planned to watch it all, more of a ‘give it a chance’ type of sit down, but it got its claws in early on. I failed to escape the sofa for the full hour, despite being subjected to some string theory along the way.

One of the things I learned (as opposed to being ‘bamboozled by’) was that the time it takes the earth to rotate varies slightly (a millisecond or so) each day and the reason for it is… the winds. The winds on earth actually affect the speed the whole thing rotates. And, as Columbo might say, one more thing… the speed of the earth’s rotation is slowing down, a few hundred million…

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