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GeoMagnetism

Over a series of posts I’d like to talk about lots of different aspects of this Natural force of Nature.  From Geomagnetism to the Magnetosphere and from historic Navigational compasses to Magneto-reception in animals. But first I’d like to talk about the biggest magnet on earth : Planet Earth.

The earths North and South poles exist as a result of molten iron swirling miles beneath our feet.  This liquid outer core at the centre of the earth is very active and flows in random patterns a bit like our weather.  What generates this continuous movement, is the spin of the earth in space, which is 1000 miles per hour at the equator.  Because of the spinning, a motor like effect is produced and in turn electrical currents are generated by the swirling iron.  It’s these electrical currents which are responsible for creating the magnetic fields which polarise the Earth into a giant magnet with a North and a South pole.

More interestingly the North and South poles are constantly moving and we have to make an adjustment when using a map (which has a fixed north) with a compass (which follows the moving magnetic North).  Here’s a link which explains this magnetic declination : http://www.magnetic-declination.com/what-is-magnetic-declination.php

NOAA has a very cool website about declination and this page shows where the north pole has moved over the last 400 years which was painstakingly generated from shipping logs collected from hundreds of historic journeys.  This illustration shows the movement of magnetic north over the last 100 years.  https://maps.ngdc.noaa.gov/viewers/historical_declination/

Here’s a video I posted on Vimeo showing the movement of the magnetic North Pole over the last 300 years.

As well as orienting the earth’s magnetic field lines from north to south, the magnetic field also extends out beyond the earths atmosphere creating the Magnetosphere.  Without the Magnetosphere, life on earth wouldn’t have evolved as we know it today because it shields us from the suns harmful radiation as this illustration shows.

This is also the reason we get the Northern Lights, more on this in the next post.  I’ll leave you with this rather understated quote:

“I happen to have discovered a direct relation between magnetism and light, also electricity and light, and the field it opens is so large and I think rich.”      — Michael Faraday (1899)

Animal disorientation due to Human magnetic ‘noise’

It’s proven that many animals possess a sense that make them aware of the earths magnetic field,  mice, rats, flies, bees, birds, whales, dolphins, turtles, dogs, deer, cows, snails, foxes, bats, eels and so on, have all been scientifically  proven to have ‘magnetoreception’.  This magneto sense is a precision instrument like hearing or eyesight and is sensitive to minute variations in magnetism which is why many animals have been shown to be affected by man made magnetism, namely electricity.  As Michael Faraday showed us 200 years ago, magnetism is an integral part of electricity.  Cows naturally align themselves along the north-south magnetic field as do Roe Deer but both display random alignment when in the vicinity of  electricity cables carried by pylons across fields (Burda et al., 2009) see article.

In red foxes it has been proven that interference with the natural magnetic field by humans via electric cables can have a detrimental effect on it’s hunting behaviour.  Red fox align themselves in a particular direction before pouncing on rodents underground, they are more successful in a north east direction (Cˇ erveny ́ et al., 2011).

It has also been demonstrated that the reason dogs often spin in circles whilst trying to defecate is because they may not get a good sense the earths natural magnetic field, perhaps because of electromagnetism produced in underground cables. (article)

dogs defecate to field lines

Radar, has proliferated the natural environment across the globe which produces electromagnetic magnetic waves travelling long distances through the earth, the sea and air.  Radar is used in ship navigation, mobile phone, radio and tv, air traffic control, weather monitoring and satellite technology.  There are WHO guidelines for it’s safe use in humans (article) but we are less sensitive than birds for example where it has been shown that radar does affect migratory behaviour (article).

The question that arises is to what degree are animals with magneto reception, in the air, on the ground and in the sea, being affected by the electromagnetic noise we humans emit all over the earth?  Just because we humans have an almost extinct magneto sense should we not be protecting the depleting wild biomass left on the earth ? (article)

references:

Burda, H., Begall, S., Cˇ erveny ́, J., Neef, J., & Neˇmec, P. (2009). Extremely low-frequency electromagnetic fields disrupt magnetic alignment of ruminants. Proceedings of the National Academy of Sciences of the United States of America, 106, 5708–5713.

Cˇ erveny ́, J., Begall, S., Koubek, P., Nova ́kova ́, P., & Burda, H. (2011). Directional prefer- ence may enhance hunting accuracy in foraging foxes. Biology Letters, 7, 355–357. Cook, C. M., Thomas, A. W., & Prato, F. S. (2002). Human electrophysiological and cognitive effects of exposure to ELF magnetic and ELF modulated RF and microwave fields: a review of recent studies. Bioelectromagnetics, 23, 144–157.

Cow’s magneto reception : https://www.nature.com/news/2008/080825/full/news.2008.1059.html

Dogs defecating ritual: https://www.theguardian.com/news/datablog/2014/jan/08/dogs-defecate-earths-magnetic-field-research-finds

https://frontiersinzoology.biomedcentral.com/track/pdf/10.1186/1742-9994-10-80

Eleanor Sheridan, Jacquelyn Randolet, Travis Lee DeVault, Thomas Walter Seamans, Bradley Fields Blackwell, & Esteban Fernández-Juricic. (2015). The effects of radar on avian behavior: Implications for wildlife management at airports. Applied Animal Behaviour Science 171, 241–252. DOI: 10.1016/j.applanim.2015.08.001.

https://www.researchgate.net/publication/325276009_The_biomass_distribution_on_Earth

Magnetoreception and Migration

I’m fascinated by this subject.  For hundreds of years humans have known of animal migration, at least seasonally animals appeared and disappeared, the mechanics of which have been a mystery until recently.  Science has discovered that most animals have a sense which can detect the earths magnetic field, in short they instinctively know which way is north and south.  This is a young area of science and we are still finding out to what degree this sense plays a part in the migration patterns of animals.

The animals which have been studied and proven to have a magnetic sense are: pigeons, salmon, trout, dolphins, whales, squid, octopus, fruit flies (of course), mice (of course), moles, bats, red fox, roe deer, red deer, eels, robins, turtles, dogs, geese, in fact most migratory birds – and the list goes on.  However, it is apparently a difficult sense to study compared to the other senses which is why we don’t have a comprehensive list.  Humans on the other hand don’t seem to demonstrate a clear magnetic sense at all, although there have been studies which claim to show that we do have this magneto-receptive ability.

Here Joe Kirschvink (Human Frontier Science Program, California) wearing an EEG monitor inside a faraday cage (which neutralises the earths magnetic field and induces a new field in any direction).  Kirschvink, a respected geophysicist, suggests that human Magnetoreception is a primal sense which we may have lost but is still doing experimental work in this area with colleges in Japan.

This of raises the question as to whether Humans have lost their sense of direction both literally but also metaphorically when we consider the state of the planet in ecological terms and socio equality.  If we have lost this Magnetoreception then when in our evolutionary history did it become genetically deselected and why?  Could it have been as a result of our move from hunting & gathering to farming when we first put down roots as a species around 10,000 years ago?  Perhaps we’ll never know but for me this is a rich area of postulation that will, no doubt, migrate into my own work.

magnets, iron filings, magnetic canvas (rusted) by richard paton 2017

Early Magnetic Field Navigation

The earliest basic magnetic compass, like many of humanity’s important technological breakthroughs, owes its development to the necessities brought on by warfare. Emperor Hoang-ti (2700 B.C.) used a magical stone  hung on horse drawn wagons in pursuit of his enemies giving a tactical advantage.

Lodestone is the name given to this iron rich mineral magnetite which became magnetised by high voltage lightning strikes [1] orientated itself along the magnetic field lines. As a consequence of its seemingly magical property became highly prized and worth its equivalent weight in silver.  The magnetic stone was either suspended by a thread or placed on a piece of floating wood (sometimes sculpted into the shape of a boat) on the surface of a bowl of water and by eliminating friction the stone naturally oriented itself along the North & South poles.

Later the Chinese found that they could magnetise an iron wire (or needle) by touching it to a lodestone. The needle would then become magnetised for a short time and could be stuck in a piece of  straw or cork to float and likewise orientate North & South. To maintain the magnetism of this early compass it was necessary to frequently slide the stone along the needle, a process known as “feeding the needle.”

Sailors in Europe became aware of this crude compass via the Arabs around 1000 A.D. and began developing it for use in Maritime exploration.

However, floating a magnetized needle on a liquid surface was not easy, especially in a rolling sea, so a pivot pin was developed onto which the magnetised needle could be mounted to rotate freely. This technological innovation was followed by the introduction of a compass “card,” which later became the “compass rose” showing North, South, East & West, and subdivided into 32 points. North was traditionally indicated on the card by a fleur-de-lis, probably because of the early use of marine compasses by the seamen from the ancient Aquitaine region of France, (according to  Norie & Wilson in 1889 ).

Over the ensuing 1000 years the compass as we know it today has changed very little but was used during that time to generate increasingly accurate maps that enabled a cumulative knowledge of the physical world.

The maps became a precious resource for explorers, merchants, politicians and their Navy’s.  Maps represented a tool for power and expansion, without the compass may not have been possible.  The compass was without doubt a key technology that shaped the world we live in today.  For hundreds of years the compass and the exploration it honed has been a fascination for many artists, perhaps because of the horizon of possibilities it represents.

For Vermeer it was something of an obsession.  Next I’ll look at  more contemporary artists who have used the compass, maps or navigation as a means to produce artwork.

Notes

[1] Wasilewski, Peter; Günther Kletetschka (1999). “Lodestone: Nature’s only permanent magnet – What it is and how it gets charged”. Geophysical Research Letters. 26 (15): 2275–78. Bibcode:1999GeoRL..26.2275W. doi:10.1029/1999GL900496.