The Sun
The sun is the largest object in the solar system, in which 99.8% of the solar system's total mass is concentrated. It is an almost perfectly spherical ball of hydrogen gas being fused into helium. The sun is in the main sequence stage of its life cycle. Despite its large size, it is only a medium sized star compared to other stars. At the end of its life cycle it will form into a white dwarf star.
Sun Spots
Large dark spots can be seen moving across the sun, growing larger and smaller on the way. The reason they are dark is because a strong section in the magnetic field prevents convection currents from transferring heat to that region. This area is thus cooler, by about 1500 kelvin. The appearance of sunspots follows a 22 year cycle, where the sunspots move across the sun from the poles to the equator and then back again in a butterfly pattern with each cycle taking about 11 years. During this time there is a solar minimum and a solar maximum, periods of low and high sunspot activity respectively. This is known as the solar cycle.
Solar Flares
When plasma interacts with the high magnetic field near sunspots, magnetic energy causes pressure to build up. When the pressure is released, there is a large explosion during which the energy is equivalent to 100 hydrogen bombs exploding at the same time. Energy is released across the spectrum, from radio waves to gamma rays. These flares eject particles, such as photons, protons and electrons. The flare reaches the corona, the outer most region of the sun, an area consiting of rarified gas (gas with pressure less then atmospheric pressure). The particles continue to travel towards the earth and form the geomagnetic wind from the sun. Normally, these particles are deflected away by the earth's magnetic field, which causes the phenomena of Northern and Southern lights. However, during these periods of solar flares, which increase and decrease with the solar cycle, the large amount of particles bombarding the earth causes huge displays of Northern and Southern lights, and disrupts communication of satellites, since they are not protected by the magnetic field. It also disrupts power grids on the Earth due to accelerated electrons that penetrate the earth's magnetic field and interact with electronic grids, similar to an EMP bomb. However, the gas from the solar flare is trapped by the gravity and magnetic field of the sun and arches back down to another sun spot. Sun spots come in pairs and a solar flare is the matter travelling from one to another.
This diagram shows the solar cycle of the sun, and the number of sun spots from 1957-2011.
Sun Spots
Large dark spots can be seen moving across the sun, growing larger and smaller on the way. The reason they are dark is because a strong section in the magnetic field prevents convection currents from transferring heat to that region. This area is thus cooler, by about 1500 kelvin. The appearance of sunspots follows a 22 year cycle, where the sunspots move across the sun from the poles to the equator and then back again in a butterfly pattern with each cycle taking about 11 years. During this time there is a solar minimum and a solar maximum, periods of low and high sunspot activity respectively. This is known as the solar cycle.
Solar Flares
When plasma interacts with the high magnetic field near sunspots, magnetic energy causes pressure to build up. When the pressure is released, there is a large explosion during which the energy is equivalent to 100 hydrogen bombs exploding at the same time. Energy is released across the spectrum, from radio waves to gamma rays. These flares eject particles, such as photons, protons and electrons. The flare reaches the corona, the outer most region of the sun, an area consiting of rarified gas (gas with pressure less then atmospheric pressure). The particles continue to travel towards the earth and form the geomagnetic wind from the sun. Normally, these particles are deflected away by the earth's magnetic field, which causes the phenomena of Northern and Southern lights. However, during these periods of solar flares, which increase and decrease with the solar cycle, the large amount of particles bombarding the earth causes huge displays of Northern and Southern lights, and disrupts communication of satellites, since they are not protected by the magnetic field. It also disrupts power grids on the Earth due to accelerated electrons that penetrate the earth's magnetic field and interact with electronic grids, similar to an EMP bomb. However, the gas from the solar flare is trapped by the gravity and magnetic field of the sun and arches back down to another sun spot. Sun spots come in pairs and a solar flare is the matter travelling from one to another.
This diagram shows the solar cycle of the sun, and the number of sun spots from 1957-2011.
Parts of the Sun
The sun has 5 different parts, but does not have a definite boundary like the terrestrial planets. The core is the innermost layer of the sun. This is where fusion takes place converting hydrogen into helium. The temperature of this area is estimated to be 13 600 000 degrees kelvin and the density is estimated to be 150 times that of water on earth. This area is where all the heat and energy of the sun is produced. Huge amounts of gamma rays are produced in this zone, and photons constantly enter and reenter atoms. In the radiative zone, the next zone out, the particles are transferred out from the core and heat is transferred away from the core. Particles travel in a zig zag pattern through this area, taking thousands of years to get out of the sun. The next layer is the convective zone, which is where particles are carried outwards by columns of gas. The gas closer to the core heats up, travels outwards, cools and sinks back down again - a constant cycle. The photosphere is the next layer and is the layer that we see. This area is about 6000 degrees Kelvin. This area is where sun spots form. The corona is the 'atmosphere of the sun' and extends outwards from the sun. It consists of plasma and rarefied gas. The gas of the corona is believed to be over one million degrees Kelvin.
Solar Wind
The solar wind is the streams of charged particles traveling from the sun, composed mostly of photons and electrons, that travel at 400km/s away from the sun in all directions. The corona is the source of the solar wind. The corona reaches such high temperatures that the sun's gravity can no longer hold onto it, and the particles fly away as the solar wind. It is unknown why the corona reaches such high temperatures. The area when these particles slow and stop is known as the heliosphere, the outermost region of the solar system. At the termination shock the solar wind slows down and becomes subsonic. The heliopause is the point where the solar wind is stopped by the interstellar medium, which is over 100 AU away from the sun. This is considered the final part of the solar system.
Sun Screen Debate
It has always been known that sunscreen prevents burning and skin cancer. However, new studies are showing that ingredients in sunscreen are carcinogenic (cancer causing) which can be absorbed by the skin. When the skin absorbs these particles, the risk of cancer is greatly increased. This leads to the debate with some saying sunscreen is beneficial because of the prevention of the skin damage, however because some studies show that it is not beneficial to the skin, it is actually damaging, then the question is should we wear it or not. However, the answer cannot be decided completely since studies are still taking place studying the effects of sunscreen.
The sun has 5 different parts, but does not have a definite boundary like the terrestrial planets. The core is the innermost layer of the sun. This is where fusion takes place converting hydrogen into helium. The temperature of this area is estimated to be 13 600 000 degrees kelvin and the density is estimated to be 150 times that of water on earth. This area is where all the heat and energy of the sun is produced. Huge amounts of gamma rays are produced in this zone, and photons constantly enter and reenter atoms. In the radiative zone, the next zone out, the particles are transferred out from the core and heat is transferred away from the core. Particles travel in a zig zag pattern through this area, taking thousands of years to get out of the sun. The next layer is the convective zone, which is where particles are carried outwards by columns of gas. The gas closer to the core heats up, travels outwards, cools and sinks back down again - a constant cycle. The photosphere is the next layer and is the layer that we see. This area is about 6000 degrees Kelvin. This area is where sun spots form. The corona is the 'atmosphere of the sun' and extends outwards from the sun. It consists of plasma and rarefied gas. The gas of the corona is believed to be over one million degrees Kelvin.
Solar Wind
The solar wind is the streams of charged particles traveling from the sun, composed mostly of photons and electrons, that travel at 400km/s away from the sun in all directions. The corona is the source of the solar wind. The corona reaches such high temperatures that the sun's gravity can no longer hold onto it, and the particles fly away as the solar wind. It is unknown why the corona reaches such high temperatures. The area when these particles slow and stop is known as the heliosphere, the outermost region of the solar system. At the termination shock the solar wind slows down and becomes subsonic. The heliopause is the point where the solar wind is stopped by the interstellar medium, which is over 100 AU away from the sun. This is considered the final part of the solar system.
Sun Screen Debate
It has always been known that sunscreen prevents burning and skin cancer. However, new studies are showing that ingredients in sunscreen are carcinogenic (cancer causing) which can be absorbed by the skin. When the skin absorbs these particles, the risk of cancer is greatly increased. This leads to the debate with some saying sunscreen is beneficial because of the prevention of the skin damage, however because some studies show that it is not beneficial to the skin, it is actually damaging, then the question is should we wear it or not. However, the answer cannot be decided completely since studies are still taking place studying the effects of sunscreen.