Many, if not most, ancient and primitive societies worshipped the Sun as a god.  Sun worship continues to this day in various guises around the world.  This makes a lot of sense, because the Sun has a lot of the features in common with our various cultures’ gods.

It is universally known, across all cultures from the most primitive to the most enlightened and sophisticated, that the Sun is the source of all life on Earth.  With the exception of radioactive decay, and what little heat seeps through the Earth’s crust from the hot mantle, all energy comes from the Sun.  Our food starts out as starches in plants, created by photosynthesis which is powered by sunlight.  The oil which powers our cars, aeroplanes, power stations, is the ancient remains of prehistoric life.  Life could not exist on earth without a source of power as abundant as the Sun.

Think on that for a moment.  Almost all the energy ever used on earth, by cars, televisions, lumbering dinosaurs, energy spent to raise tall trees and energy which powers huge hurricanes, it’s all from the Sun.  The Sun must be very powerful indeed!  And when you consider that the earth is roughly one hundred and fifty million kilometres from the Sun, and intercepts only the most minuscule percentage of the energy which the Sun sprays out in all directions, then we find that our minds simply can’t conceive of the power involved.

It is a popular science fiction premise that some clever person can drop a bomb into the Sun and affect it – sometimes the Sun is dying and needs a kick-start, sometimes they’re a super-villain who is planning to blow the Sun apart, or boost it’s power so that it’s fries Earth.  Sometimes it’s a different star altogether, but since the Sun is a very typical average star, this makes no practical difference.  But consider this:  It’s a popular factoid that there are enough nuclear weapons stored by the various superpowers to sterilise the earth, and strip away the crust to a depth of umpteen kilometres.  But all that destructive power, concentrated to a point and focused on the surface of the Sun would simply be lost amongst the normal daily turmoil of sunspots, granules, supergranules, convection cells, and other phenomena.  The Sun is very big, very violent, very hot, and utterly impervious to any possible human interference.  In fact, throughout the universe, the only things known to have any effect on stars are other stars (or the remnants of dead stars), and the supermassive black holes which we now know exist at the centres of galaxies.

Our sun is about three hundred and thirty three thousand times as massive as the earth, yet is made almost entirely of Hydrogen and Helium.  You could line up more than one hundred planet Earth’s, end to end, and they would fit inside the Sun.  The sun, at it’s core, is a precisely balanced nuclear fusion reactor.  The centre of the Sun is so hot that there is no such thing as solid, liquid or gas.  The very atoms that make up matter are torn apart leaving a soup of atomic nuclei and electrons, called Plasma.  Within the core, at a pressure three hundred and forty billion times that of the Earth’s atmosphere at sea level, and a temperature of around fifteen million degrees celsius, hydrogen nuclei are smashed together with so much force that some of them fuse together, producing helium and a small amount of energy.  Some five million tonnes of matter are annihilated in this fashion every second, producing energy equivalent to ninety one billion megatonnes of TNT.  It’s no wonder, then, that even at it’s great distance, it has such a dramatic effect on the Earth.

There are many dangers posed to us from the Sun.  In about five billion years, it will begin to run out of hydrogen fuel, and the nuclear reactions will begin to slow down.  The Sun will no longer be able to support its own weight, and will start collapsing in upon itself, raising the temperature and pressure until finally a new fusion cycle can begin, fusing the helium ‘ash’ into heavier elements.  These reactions are far more violent than mere hydrogen fusion, so the Sun will balloon to a much greater size than it is now, to the point where it will completely engulf the orbits of Mercury and Venus, and boil away Earth’s oceans and extinguish all life.  But this will just be the final coup de grâce – the Sun has plenty other smaller tricks to play on us.

The most common and well known threat is ultraviolet radiation, but in fact the Sun bombards the Earth with a frightening barrage of electromagnetic radiation, right across the electromagnetic spectrum.  Fortunately, Earth has a formidable shield in the form of her atmosphere which protects us from the most damaging rays, but human activity has done much to weaken these defences in the past few decades.  The ozone layer is an extremely thin layer in our atmosphere, composed of an allotrope of oxygen called Ozone (O³). To satisfy our fondness for fresh food and smelling nice, the human race manufactured millions of tonnes of chlorofluorocarbons for use in refrigerators and aerosol cans.  Unfortunately, when this gas is released, it floats up into the upper layers of the atmosphere where it reacts with ozone, destroying it.  This means that in areas where the ozone is thinner (the famous Ozone Hole), much greater amounts of ultraviolet radiation seep through, so that now in South Africa, Australia, and other sunny countries in the south, we get serious sunburn very easily, and incidences of skin cancer are very high.

Then we have infra-red radiation.  If you hold your hand near a hot object and you feel the heat radiating off of it, you are feeling the effects of infra-red radiation.  The sun puts out a lot of this, although most of it is absorbed by the moisture in our atmosphere.  Enough makes it through, though, that we can distinctly feel it, and focus it through a lens to light fires or torture ants.  This is also the mechanism by which careless sungazers can blind themselves.  Most makeshift filters (Welding goggles, for example) filter out visible or ultraviolet light, but not infra-red.  The retina has no pain receptors so we stare happily away, unaware that all that heat is being focused to a point on our retinas, slowly burning it away.

In addition to these directly harmful emissions, the Sun also ejects a great deal of subatomic particles and ionized atoms, in the form of the Solar Wind.  When this reaches earth, it is neatly deflected by the Earth’s magnetic field, but a strong enough burst can distort the field and cause havoc with electrical equipment.  Currents can be induced in power lines, causing the electricity grid to shut down.  Satellites can have their circuits scrambled, the ionosphere can be disrupted making long range radio communications impossible.  On the plus side, however, people near the Earth’s poles get to see spectacular auroral displays as a result of these interactions.

If we leave the safety of the Earth, then we experience the full force of the Sun’s onslaught.  Space ships travelling far from the earth have to be equipped with radiation shielding, and even then they have to continuously monitor the sun for heavy activity which will boost the solar wind.  So far, astronauts travelling out beyond the magnetosphere have relied on the short durations of their journeys (a little under two weeks for the moon missions, a great deal less usually), but extended missions to places like Mars will take months or years to complete, and the solar radiation will be a very big important problem to solve.

So there we have it.  The Sun gives, and the Sun takes away.  It is awesomely powerful, and it has the power of both life and death over every living thing on Earth.  How very fortunate for us that it is a natural (and extremely common) phenomenon, that it has no personality, that it doesn’t know we exist, or care, that it is not a god.  And how lucky we are to live on a planet where everything from the orbital position to the composition of the atmosphere, to the strength of the magnetic field, is perfectly tuned to provide us what we need from the Sun, and filter out what we don’t.  Because while the Sun provides, it does so in the most violent possible way, and we could not possibly survive without our nice cosy environments protecting us.

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