Wednesday 16 June 2010

Solar Flares And Sunspots - Should We Be Worried?

There's been a sudden explosion of "The End Of The World Is Nigh" articles in the press recently, prompted by NASA's recent warning over increased solar activity over the next few years.  Planes will fall out of the sky, power grids will go down and the internet will be deleted....apparently, and according to your choice of newspaper.
So what's the truth, and how worried should we be?
There's two main issues here, the recent activity (or lack thereof) on the Sun, and our increased susceptibility to space weather.

Solar Activity 
The Sun goes through cycles.  That's been known for well over a century, and records of various kinds go back nearly three millenia - the first recorded sunspot observations were in China circa 800 BCE and professional astronomical observations have been carried out for the last hundred and fifty years.  

This figure was prepared by Robert A. Rohde and is part of the Global Warming Art project.

Solar cycles seem to have a fairly powerful effect on the Earth.  Archaeological records using radioisotope measurements, pollen samples and dendrochronology (a fancy name for what  is effectively "counting tree rings") have shown some fairly drastic changes in temperature and weather which appear to coincide with solar cycles - the recent Little Ice Age, involving a drop in temperature of about 1C across the Northern hemisphere, occurred in synchronisation with the Maunder Minimum, the red bit on the graph above.  
None of this means that solar weather was a direct cause of the change in Earth weather, "correlation is not causation" being an important thing to remember, but given that the Sun provides almost all of the energy driving the Earth's climate it's a strong suggestion that we should be paying close attention to what the Sun is up to.
So what, exactly, is it up to at present?  We've recently gone through one of the quiet periods.  In fact August 2009 was one of the only sunspot-free months ever measured, and sunspots seem to be a good measurement of solar activity.  We should have seen activity pick up a little in the last year or so, in preparation for a peak around the end of 2012 or early  2013, according to the graphs and predictions anyway.  That doesn't really seem to be happening though. 
 The Sun is staying quiet, that's one of the reasons I got so excited recently when I managed to snap a picture of a couple of sunspots.  And this is essentially why people are getting concerned, the simple lack of the Sun "doing what it's supposed to".  
Does this mean that it's going to stay quiet and we're going into another mini-ice-age?  Or does it mean that the Sun is building up to a doozy of a big event?  The evidence can point either way...the history of quiet periods is clearly there, so that's a possibility, but the Sun's cycles are also driven in part by a build-up and sudden release of energy, so the quiet spell at the moment could equally well herald a fairly spectacular burst of activity in the next few years.
Long story short, nobody really knows at the moment, and that's what's scary.

 The Effects On Human Civilisation
This is the second issue that needs to be looked at in depth.  Let's presume that the Sun is, in fact, building up to a big event.  What's likely to happen on Earth as a result?

The last big solar event recorded was the Carrington Event of 1859.  Numerous sunspots and solar flares appeared, aurora (Northern Lights) were seen all over the northern hemisphere as far south as the Caribbean, telegraph systems failed across North America and a "coronal mass ejection" (CME) was even observed, basically an explosion on the Sun that sent a huge glob of solar matter streaming towards the Earth.

Sunspots are cool, and CMEs are one of the most spectacular events in the solar system, thankfully mostly deflected by the Earth's magnetic field, which is what causes the oh-so-pretty aurora.

United States Air Force photo by Senior Airman Joshua Strang - Public Domain

The bit we should be concerned about, however, is the telegraph failure.  Not because we still use the telegraph system, but because of why it failed and what it became.
The failure was caused, in essence, by the fact that the telegraph system used long bits of wire.  When the stream of particles from a solar event hits the Earth's magnetic field it is diverted away from the Earth....but something has to give, and that's the Earth's magnetic field.  It bends and warps as it absorbs and redirects the energy, and when you wave a magnet around next to a long piece of wire it heats up.  Effectively, the telegraph system started to behave just like an induction cooker, and it was never designed to do that.  The wires got hot, current surged through them and fuses blew.  Any long piece of wire will do the same - in 1989 Canada lost large parts of its power supply system because of a solar storm.  
Whilst we don't have much of a telegraph system these days we do have what it turned into - a worldwide power supply and information transmission system.  The internet, phone lines, power supplies, email, computers, banking, trading.....much of modern civilisation is based on long, thin bits of metal wire, and we rely on it in a big way.
A large solar event could, worst case scenario, take down much of our infrastructure and cause damage and economic repercussions that would make the current economic crisis look like child's play.  No internet, few communications systems, a massive loss of data...half of the things needed to repair the problem would be lost in the problem itself.  Satellites have even bigger problems...they sit right in the middle of the field, so they are still subject to the induced currents but lose some of the shielding.  This is a known issue - British company QuinetiQ (formerly part of the Ministry of Defence's research department) specialise in trying to protect orbital systems from this kind of damage.
It's not all doom and gloom however - optical fibres, for instance, aren't subject to magnetic fluctuations like this, and the nature of the internet is such that it will naturally try to route around fact it was originally designed as a communications system that could still operate after multiple nuclear strikes across the US.  Power supplies, too, are designed to back themselves up, although this redundancy has been known to cause "cascade" style outages where system after system goes down trying to pick up the slack from the others.
So in conclusion, should we be scared?  Well, no.  Concerned?  Absolutely.  Prepared?  It never hurts.


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