The S U N

INTRODUCTION

Our Sun, somtimes called Sol lies as the very heart of the Solar System. In many early cultures it was worshipped as the supreme god, whose grace and thanks should be given for its glorious rays of warm light and allowing all the peoples of the Earth to live and thrive. There were always fears that if the Sun was not honoured properly, then the god may become angry and extinguishing its important light - plunging the Earth into permanent darkness. This idea was perpetuated by occasional solar eclipses threatening to consume the Sun unless the god was appeased in some way. To the Ancient Egyptians under Tutmosese IV this god was Aten. For the Greeks it was the god Apollo, who daily rode his celestial chariot across the sky under the power of four celestial horses.

Sol is in fact a star, similar to all the ones that appear in the night-time sky. Obviously, the difference is that the Sun is very much brighter due to its proximity to the Earth. The next nearest star is nearly 40 000 times the distance between the Sun and the Earth, being the Alpha Centauri triple system, where Proxima Centauri happens to be slightly closer at 4.3 light-years. Some other stars seen in the night sky are similar to the Sun but the vast majority is either hotter or cooler, larger or slightly smaller, brighter or less luminous. In the scheme of things our Sun is considered to be just an ordinary yellow dwarf star with no particular outstanding or unusual peculiarities. The smaller mass of the Sun does produce one advantage - as the energy will last between eight and ten billion years, unlike the largest stars, which have much shorter life-times. The Sun at present is only about half way through its evolution.

From its tremendous output of light, all the planets, the Moon, asteroids and comets and shine brightly by simple reflection. Solar energy is manufactured constantly and continuously, allowing for the Earth’s stable environment that harbours and sustains all terrestrial life. The Sun does, however, slightly fluctuation in brightness over the millennia - contributing to the Ice Ages known to have occurred many times in the past. The present warm climate of the Earth may also be affected in the short term by such changes and the number of sunspots visible on the solar disk.

The volume of the entire solar sphere occupies a ball of very hot gases, primarily made from two main elements; Hydrogen (73.46%) and Helium (24.85%), which make up a total of 98.21% of the mass. The remaining 1.79% is made up of all the other chemical elements.

Comprising the outer observed ‘surface’ is the photosphere, whose effective temperature is 5 778 K. In the central radiative core this temperature rises to an estimated fourteen million degrees (14,000,000 K).

Matter in the core is very unlike the rest of the Solar System, existing as ultra-hot plasma - the fourth state of matter. In this environment, all electrons normally orbiting the atomic nuclei are completely stripped away by the very high temperatures and pressures. Each atomic nuclei can collide together, mostly being deflected by the strong nuclear forces. Sometimes they hit so hard that the kinetic energy overwhelms the strong nuclear forces so they fuse together, creating heavier atoms as different chemical elements. This is the important process is known as fusion, generally referred in astronomy as nucleosynthesis.

In the Sun lies vast stores of Hydrogen dwell. Here in the core, several million tonnes per second of Hydrogen are converted to the heavier Helium - something in the process that also creates copious quantities energy. In the core only a small percentage of the atomic mass is destroyed, with the net outcome being simply stupendous amounts of liberated energy I.e. The solar energy is 6×10²⁶ Watts each second. (See Note Below.) So in this particular view, the Sun is really a gigantic power plant of light and heat.

[NOTE: Discovery of liberated energies via fusion was Albert Einstein in 1905 is his famous mass-energy equivalence equation E =m&215;c² (energy equals mass times the speed of light squared), as first published in the landmark paper; “Does the inertia of a body depend upon its energy-content?” In terms of a typical 600 MW. (megawatt) nuclear power station, our Sun produces 10¹² - or one trillion or 1,000 billion times more energy every second!
If just one gram (1g.) of matter were converted into pure energy, the total power released is equal to 25 million kilowatt-hours or about 9×10¹⁶ Joules of energy. Comparing to the average quarterly power bill of 2,000 kilowatt-hours, this is 12,500 times more in total energy consumption. At, say, 12 cents per kW the amount (2008), this is equal to about $3,000,000 worth of consumed electricity or 50,000 consecutive power bills, or enough power for 12,300 years!
So if we based our calculations on the entire net electricity generation on Earth in 2004, by all sources, it was predicted to be 1.665×10¹³ kW-hours (or 16,650 billion kW-hours) then it would take the equivalent of converting 655 kilograms of matter into pure energy each year, 1.8 kilograms per day, or just 21 grams per second - merely using 950 trillionth of the solar energy production in the same ssecond! Just Amazing!

• It is interesting that this consumed energy is actually 1.5102×10¹³ kW.-hours (15,102 billion kW-hours), meaning the energy lost is about 1,540 billion kW-hours or 9.3%. This significantly loss is probably due to energy transmission leakage via power lines or from heat dissipation.
Source: Energy Information Administration E.I.A. Energy Statistics U.S. Government (2008)]

Hydrogen is not the only element that can be fused in this way, as there are other rarer conversions, that normally required higher core temperatures. (They can occasionally occur at lower temperatures, by the actually probability of this happening decreases rapidly.) These different processes are established reactions that also occur in other stars. Here the Hydrogen is converted into Helium, then next is Helium into Carbon, Carbon into Silicon, and finally Silcon into Iron. Many sub-reactions can also exist, where, for example, Helium can convert into either Oxygen or Nitrogen (and rarely, Fluorine), etc. Simplistically, the Sun in reality is a elemental chemical factory, manufacturing all the common elements that are found on the Earth and found within our human bodies.

Once these energies reach the solar surface, it radiates light equally into all directions into space. Our Earth receives only very tiny fractions of this energy, but despite the distance of about 150 million kilometres, the amount received is so intense that the retina of the eye can be quickly damaged causing irreparably and permanent blindness . Also the UV radiation begins to disrupt external body cells like skin.

COMOSITION of the SUN

!!! W A R N I N G !!!

Using any telescope, the Sun should ONLY be observed by projecting the image on to a white screen or card. (Even this should be for short periods)
Direct viewing of the Sun, by either eye or any other optical equipment, is VERY DANGEROUS without proper eye protection. Otherwise, TOTAL BLINDNESS WILL RESULT, and even glancing will blind you in less than a ten-thousandth of a second.
If your telescope has something called a SUN FILTER - NEVER USE IT !! If this filter were to crack while you are observing the Sun, INSTANT blindness is the only possible outcome.

!!! W A R N I N G !!!

(NOTE : PLEASE READ THE DISCLAIMER BELOW.)

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Important Disclaimer

The user applying this data for any purpose forgoes any liability against the author. None of the information should be used for regarding either legal or medical purposes. Although the data is accurate as possible some errors might be present. The onus of its use is placed solely with the user. Those not heading the given important warnings written in red on this page do so at their own risk.

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Last Update : 2nd September 2008

Southern Astronomical Delights
© (2008)

For any problems with this Website or Document please email me.

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