Burning bright as our star, the sun remains the basis for all energy sources in our solar system, including all those found on earth. As such, most find it unarguable that our sun is the most important piece in our solar system contributing to the existence of mankind. But how does the sun produce such vast amounts of energy, while continuing to burn bright with the coming of each day? The age old fallacy of a ball of fire burning bright in the sky is unfortunately not the way our sun produces the energy it does. If the sun were in fact on fire, we would have long ago ceased to exist, as the life span of our star in such a scenario would only sit at 10,000 years before its source of fuel had been burnt to ashes. The later theory of gravitational contraction, that is, energy production through heat caused by massive gravitational forces, would only place the sun at a lifespan of 25 million years, again removing its current existence from question. The actuality of the suns constant energy source lies in the concept of Nuclear Fusion, correctly placing our sun at a long life of an average 10 billion years, allotting several billion years more of renewable energy to continue its course through our solar system.

      But still, what exactly is our sun composed of, if fire remains out of question? Unusually enough, the sun’s composition consists of a substance known as plasma, the fourth state of matter. In essence, plasma remains the product of partially ionized and superheated gas molecules, acting as a substance that defies the properties of solids, liquids, and gases. Plasma, however, is not a new concept to humankind. Plasma is created artificially on earth and found in many items we come in contact with each day, such as fluorescent lights, and even televisions that lend their name to the substance itself ; plasma TV’s. The sun stays in its constant shape, providing a constant energy level through a natural process entitled, “hydrostatic equilibrium.” Hydrostatic equilibrium describes the process through which outward pressure and gravity reach a state of balance, or equilibrium. The energy produced within the core of the sun pushes outwards with heavy force, which if isolated would blow the sun apart. However, the size of the sun creates a gravitational inward pull that balances out this outward force, equalizing and stabilizing the sun’s size and shape, allowing for a constant star to burn brightly for billions of years.

      As small as the sun appears in the sky, many seem too underestimate the actual size of our great star at 333,000 times the size of the earth, and a volume over one million times that of our own. But as plasma, this burning behemoth is not a solid, with its equator rotating notably faster than its poles. An interesting feature of the sun, which causes noticeable effects here on earth, is the solar wind produced every second. This solar wind is composed of charged particles and electromagnetic radiation from the suns surface. We can see the solar wind from earth because of the high quantity of light bearing photons spread ablaze with the wind.

      The suns atmosphere is typically divided into three separate parts: The Corona, the chromospheres, and the photosphere. The outermost layer of the sun is the Corona, which comprises the entire outer atmosphere. The corona is actually larger than the sun itself, burning at an average of 1-2 million degrees Kelvin, with some regions reaching an extraordinary 20 million degrees. The corona as a whole is nearly transparent, only visible during a total solar eclipse. Next lays the chromospheres, which visually remains a pinkish transparent layer, visible only in a total eclipse, or an annular eclipse. The chromosphere is usually characterized by jets of gas streaming upwards in what are known as spircules. Finally, the photosphere lends itself as the third layer of the sun, the layer which remains constantly visible to our eyes. At 5800 degrees Kelvin, the photosphere remains the layer at which all light from the core is emitted, and even determines the color of the sun.

      The surface of the sun is noted for its pattern of granulation, or the boiling, marbled like pattern caused by the convection of gases in layers below. This is a very dynamic event, and can be easily measured by Doppler shift detecting radars here on earth. Super-granulation lends its name to the large regions of granules, each bubbling at a size near that of the earth. The radiation zone under the surface of the sun describes the zone in which energy is transported from the core in which it is released, to the surface where it escapes. The photons that are a part of this energy move with a random pattern under the surface, making a slow rise to the surface where they are emitted. This random pattern can take hundreds of thousands to millions of years to actually escape. Interestingly enough, the light that we see on earth was actually most likely created about a million years ago!                     

      Sunspots remain a common form of solar activity, and have been recorded for hundreds of years. These large dark regions vary in size and time occurrence, but are surrounded by high magnetic fields that can sometimes disrupt electrical equipment here on earth. Though these sun spots appear dark in comparison the rest of the photosphere, they are actually incredibly bright. It is only in comparison with its surroundings that each sunspot looks dark and dull.

      The sun’s core is perhaps the most interesting part of the anatomy of our star, creating all the light we see and energy we utilize on a daily basis. As stated before, the energy within the sun is generated by nuclear fusion, heating the core to an average of about 15 million degrees Kelvin. The atmospheric pressure within the core is nearly 240 billion times that of the earth’s atmosphere! Even with all the energy emitted from the sun, only .7% of the mass within the core is converted into energy. One gram of matter alone within the sun is converted into energy worth 300,000 tons of coal. The suns energy comes through a process known as the proton-proton cycle, which remains a three step process of nuclear fusion resulting in the energy we see and record. Under great pressures created by the sun’s sheer size, hydrogen atoms are constantly fused together. This remains the first step of the sun’s fusion process. In stage one, a single hydrogen atom will fuse with another hydrogen atom, to create a hydrogen isotope commonly referred to as deuterium. Next, this deuterium will then come together with another single hydrogen atom to now form an isotope of helium. The final stage consists of the fusing of two helium isotopes, creating a loss of two protons in the form of an energy reaction. There are essentially two requirements for nuclear fusion: High temperature and high density. This three step process creates all the energy the sun will ever utilize and emit.

      With reactions of such unstable proportions, how does it remain possible that the sun’s temperature does not drastically alter? Luckily, our sun is embedded with a self-working thermostat of sorts, allowing a balance in temperature in size. For example, if the suns core temperature were to rise, the core would then begin to expand, and eventually cool off, shrinking back to its original size and continuing its energy production. Yet, if the core’s temperature were to somehow cool, the rate of nuclear fusion would decrease, and the core would compress, raising the temperature due to higher density, and the temperature would then self-stabilize back to its original optimal levels.

      The study of our sun through solar vibrations is specifically referred to as Helio-seismology. Within the sun, sound waves bounce in random pattern, eventually making contact with the undersurface of the photosphere, creating bulges in the outer surface. Doppler imaging shows the velocity field over the solar surface, and then allows scientists to understand the complex makings of the suns interior.

      Another way scientists are able to image the interior portions of the sun is through the mapping of neutrino particles given off during nuclear fusion within the core. These Neutrinos fly directly out of the sun in all directions, small portions striking the earth. Machines built to calculate the origin of these neutrinos allow astronomers to lightly map the actual core of the sun, giving us knowledge of the suns inner processes of nuclear fusion and much more.

      Our star, the sun, is the key to all of life here on earth, and remains the cornerstone symbol of power and might in all lands and cultures. It’s importance has never gone unnoticed, as it continues to provide the energy and light needed to sustain a world and solar system of constant wonder and amazement.