Aurora Borealis

Without the magnetic field generated by the earths liquid iron core two thousand miles beneath our feet we wouldn’t have the spectacle of the Northern Lights.

This is a phenomena whereby the magnetic field producing the North and South Poles at either end of the earth have the strongest magnetic pull.  Charged particles emitted from the sun during increased sunspot activity, also known as coronal mass ejections, create radiation also known as ‘solar wind’ which dragged toward the North and South poles.

The magnetosphere is a magnetic shield that protects us from the majority of this solar radiation but the charged particles which do get though do so during increased activity during the suns 11 year cycle.

The bright colours are generated when the charged electrons and protons collide with the gases in the earths atmosphere and are converted into photon energy that lucky observers can see when near the poles at night during increased sun spot activity.  Oxygen in the upper atmosphere emits green or orange-red, depending on the amount of energy absorbed.  Nitrogen emits blue or red; blue if the atom regains an electron after it has been ionized, red if returning to ground state from an excited state.

Scientists have discovered how the Earth’s magnetic field fluctuates, but also weakens and reverses dramatically every 200,000 years or more.  The next flip is overdue and scientists have observed significant weakening of the magnetic field over the last 100 years decreasing in strength about 5 percent per decade and some believe this is the beginning of a polarity reversal.  During this event the earth’s magnetic shield is reduced and the charged particles would hit the earth everywhere on the side facing the sun, creating an Aurora spectacle for everyone to see.  The downside is that there would be a corresponding increase in cancer rates as we are bombarded with harmful radiation we are currently protected from by our magnetic field.

This image shows a computer generated model of the Earth’s fluctuating magnetic field thousands of years ago based on data from lava samples which have fixed the earths magnetic field in the rock as they cooled down.

In the piecing together of the moving magnetic field over 100’s, 1000′ s and millions of years brings together unlikely disciplines analysing navigational maritime charts, ancient pottery and geo magnetic core samples.

This film  helps visualise the aurora and how the earth’s polarity is due to flip :  http://www.aurora-service.eu/aurora-school/aurora-borealis/

The Planck space observatory used by the ESA 2009 – 2013 gathered magnetic field data of our Milky Way galaxy producing this image.

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 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.

Brainwaves are a bit like the Earths magnetic field lines

It’s amazing to me that the brain also generates magnetic fields outside of our heads.  Perhaps this is what some people call the ‘aura’ of a person but I’ll leave that for another day. Proof of these magnetic fields are evidenced in the use of very sensitive magnetic sensors which are placed on the head, usually by neuroscientists conducting experiments, which pick up electrical wave lengths via the magnetic fields they produce.  Neuroscientists can look at the graph produced by the EEG (electroencephalogram) and make diagnoses like epilepsy or sleep disorders.  Magnetoencephalogram (MEG) headset technology is able to detect magnetism deeper in the brain (without any ill effects on the subject) and can give a more detailed picture of the cognitive processes in different areas in the brain whilst performing different activities.

Magnetoencephalogram (MEG) 3D printed headset developed by Nottingham University.

Richard Bright is an artist using EEG technology in his artwork who gave a talk at London Laser Project (a Leonard initiative) based at Central Saint Martins.



check out China Blue for her EEG interactive sound sculpture

Imagining Blue

Lisa Park also uses EEG in her performance work :  http://www.thelisapark.com

 

GeoMagnetism – North & South Poles

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/

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)