How the Sun Produces Heat and Light? - Essay Sample

Introduction

The Sun is a star situated at the heart of the Solar System. It is remarkable from other stars as the earth, and other planets revolve around it and contribute about 99 percent of the total mass. The sun is composed of three main parts. They include; the core, the radiative, and the convective zones. The core makes 25 percent of the radius. The radiative zone makes 45 percent of the total radius, and convective zone takes the remaining 30 percent. Understanding how the sun produces heat and light by nuclear fusion enables one appreciate fundamental concepts of physics such as laws of energy.

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The sun dissipates energy at a substantial conversion rate of 42.6 million metric tons per second; this produces an equivalent of 38,500 septillion watts per second. Putting this into perspective, is an equivalent of 9.2*1010 megatons of TNT per second or 1.8 billion Bombas, one of the most powerful thermonuclear bombs ever designed.There are many theories explaining on how the sun came into existence. It is believed to have started when a massive cloud of gas and particles collapsed under the force of gravity. This created a giant ball of light at the center of the solar system and initiated a process where the hydrogen collected began fusing to develop solar energy.This is one theory that scientists believe known as Nebula Cloud theory.

The sun produces energy through nuclear fusion reaction facilitated by quantum tunneling. Quantum tunneling allows particles to exceed the energy barriers which would be impossible under normal conditions. The nuclear fusion process takes place at the core of the sun. It is here where energy is produced by the conversion of hydrogen atoms to helium. This process requires high pressure and temperature to occur, available in the core. This is due to the gravity of the sun which pulls its mass towards the center. The pressure is estimated to be about 250 billion atmospheres and a temperature of 15.7 million kelvin (https://phys.org/news/2015-12-sun-energy.html).

The process results into the fusion of four protons of hydrogen molecules into one alpha particle. This constitutes two neutrons and two protons bound together into one particle similar to the helium nucleus. The first collision forms deuterium which is a heavy hydrogen atom made of one proton and neutron. In the second collision, the deuterium collides with the proton, the result is a helium-3 made of two protons and one neutron.Helium-3 is unstable chemically which results in a third collision where two helium-3 nuclei collide to form a stable helium nucleus. The stable helium nuclei consist of two protons and one neutron. The three collisions produce gamma rays which are an energy-rich form of light. (https://phys.org/news/2015-12-sun-energy.html).

These fusions produce tremendous energy as they are exothermic reactions. This is explained by Einstein's formula ; energy equals mass multiplied by the velocity of light E=m*c2.At the beginning of the fusion, there are four protons having a mass of 6.7 *10-27 kg and in the end, helium nucleus of 6. 65*10-27 kg. From the reaction 0.05 * 10-27 kg is lost which seems negligible. However, when multiplied by the square of the speed of light, 3*108 m/s and there are numerous fusions per second. It yields a massive amount of energy; 3.4*1026 joules per second ( Herschel 1801).

The energy is released in form of gamma rays which are referred as lumps of energy. These are massive amounts of energy, putting this into context means the sun produces as much energy each second that the world's population cannot consume in 600,000 years. This is a lot of energy that is hard to imagine. The gamma rays take about 100,000 years to reach the surface of the sun. This is due to the collisions with particles as the sun is made of a dense material; in this process, some amount of energy is lost. As a result of these collisions, gamma rays are referred as photons on the surface of the sun which travel at the speed of light.

All the energy produced by the sun takes place in the core. This is because the conditions for fusion are not available in the other layers. The rest of the sun, therefore, gets heated by the energy that moves through the different layers from the core. The energy eventually reaches the outer layer and escapes into outer space as particle energy which is commonly referred to as sunlight.

The radiative zone surrounds the core. It is made of hot and dense solar material necessary to transfer heat produced by radiation. In this zone, there is no heat transfer by convection. This mainly involves hydrogen ions and helium emitting ions that travel for short distances before being absorbed by other ions. There is a tremendous drop in temperature from 7 million kelvin to 2 million kelvin at the boundary with the convective zone. Density drops by hundredfold from 20g/cm3 to 0.2g/cm3 at the upper boundary.

The peripheral layer-convective zone is responsible for everything further than 70 percent of the inner radius. It is characterized by heavy ions that are not entirely ionized. This results in the inefficiency of heat transfer by radiation and therefore, convective currents develop due to the low density of the plasma. The rising thermal cells carry most of the heat to the photosphere. On reaching the photosphere surface, the cells cool leading to increase in density. Density and mass are directly proportional; increase in density means the cells becomes heavier hence returns to the convective zone and the process repeats itself. This convection is responsible for producing both magnetic poles on the surface of the sun. Also, sunspots occur in this region where dark patches appear compared to the adjacent area. These spots are as a result of magnetic flux concentrations which hinder convection causing temperature decrease on the surface compared to the adjacent material.

The photosphere is the visible surface of the sun. It is in this region where heat and sunlight are radiated and convected to the surface and hence into space. The upper part is cooler than the lower part, which makes the image of the sun appear brighter in the middle than the edges. This phenomenon is known as Limb Darkening.

In addition, in this region the sun is opaque hence light is visible. This is due to reduction in the amount of negatively charged hydrogen ions which absorbs visible light. Therefore the visible light that we see is produced as electrons react with hydrogen atoms which produces negatively charged hydrogen ions.

Above the photosphere exists the solar atmosphere which is made up of corona and chromosphere. It is in this region where sunspots and flares are observed.This is as a result of the visible light at the top of this region being very weak to be seen against the photosphere which is bright. However, during a solar eclipse, the moon covers the photosphere which makes the chromosphere look like a reddish rim around the sun. The corona ends up forming white crown with plasma ribbons which resemble flower petals.

The energy discharged from the photosphere spreads through space. It eventually reaches the planets on the solar system which includes the earth's atmosphere. The upper layer of the atmosphere, ozone layer filters ultraviolet rays, but some reach the earth. The energy is then absorbed by the air and crust which heats up the surface providing power to living organisms.

Recently, research has shown that the sun undergoes cycles which change its behavior. It is approximated that after every 11 years the magnetic polarity of the sun's geographic poles varies. When this occurs the chromosphere, corona, and photosphere become violently active. This phenomenon is known as solar maximum, and it is when solar storms occur where the sun releases large amounts of energy some of which reaches the earth. This tends to destroy satellites and to affect power lines (https://solarsystem.nasa.gov/solar-system/sun/in-depth/).

Conclusion

In conclusion, the sun produces heat and light by the process of nuclear fusion which involves three cycles of the collision. All this happens in the core of the sun due to the high temperature and pressure available. The sun plays a vital role in supporting life on earth as the energy it produces is essential for both biological and physical processes.

References

Solar System Exploration: In Depth. (2018). Solar System Exploration: NASA Science. Retrieved 16 April 2018, from https://solarsystem.nasa.gov/solar-system/sun/in-depth/Herschel, W. (1801). XIII. Observations tending to investigate the nature of the sun, in order to find the causes or symptoms of its variable emission of light and heat; with remarks on the use that may possibly be drawn from solar observations. Philosophical Transactions of the Royal Society of London, 91, 265-318.

How does the sun produce light? - Humbot - Your Smart School Buddy. (2018). Humbot.io. Retrieved 16 April 2018, from https://humbot.io/How-does-the-sun-produce-light

How the Sun Produces Light and Heat :: temperature, hydrogen, nuclear fussion. (2018). 123helpme.com. Retrieved 16 April 2018, from http://www.123helpme.com/how-the-sun-produces-light-and-heat-view.asp?id=410781How does the sun produce energy?. (2018). Phys.org. Retrieved 16 April 2018, from https://phys.org/news/2015-12-sun-energy.html