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The Sun:
The Sun is a star, a hot ball of glowing gases at the heart of our solar system. With a mass of 1.989E30 kg, a diameter of 1,390,000 km and a surface temperature of 5800 K, it is the biggest object to be found in our solar system.
The Sun is made up of 6 parts:
The Core:
The core is the very centre of the Sun. It has an average temperature of 15,600,000 K and is the source of the star’s energy. Because of the core’s immense heat and the material in the core being so dense, it creates an environment just right for nuclear reactions to occur. The core is about 347,500 km in diameter.
In the core, the intense heat destroys the internal structure of an atom and therefore all atoms are broken down into their constituent parts. Neutrons are the first to leave the core as they do not have an electrical charge therefore, they don’t react to the surrounding medium. The protons and the electrons remain in the core and drive the reactions which fuel the Sun, together making plasma. The high temperature provides the protons and electrons with a large amount of thermal energy and as a result they move around quite quickly. This motion, combined with the high density of the plasma, causes the particles to continuously slam into one another creating nuclear reactions. It is the fusion of these particles that provides the energy source for the Sun.
The Radiative Zone:
The radiation zone is the next layer to the Sun, which surrounds the core. It is about 70% of the Sun’s radius. Inside the radiative zone, the energy generated by nuclear fusion in the core moves outward as electromagnetic radiation. This radiation does not take a straight path to the radiative zone’s edges, more following a random path inside the zone before making its way to the zone’s surface.
The Convection Zone:
The convection zone makes up the outer shell of the Sun. Here is the energy flows much faster than the radiative zone because of the process of convection. Hotter gas coming from the radiative zone expands and rises through the convective zone. This is because the convective zone is cooler than the radiative zone and therefore less dense. As the gas rises in the convection zone, it cools and begins to sink down again. As it falls to the top of the radiative zone, it heats up and begins to rise again. This process repeats, creating convection currents and the visual effect of boiling on the Sun's surface.
The Photosphere:
The next layer of the Sun is the photosphere, which actually is part of the Sun’s atmosphere. The photosphere is a very thin layer in comparison with the rest of the Sun. It is the only part of the Sun that we can actually see when looking at it from Earth, because the photosphere is where the light is emitted. The photosphere actually absorbs much of the light from the Sun because of its opaqueness. In the photosphere, granulation, supergranulation, faculae, and sunspots are found.
The Chromosphere:
The chromosphere is a narrow layer above the photosphere that rises in temperature with height. It is about 2500 km thick and is normally not visible with the naked eye because of the light from the photosphere being much stronger. However, during a solar eclipse when this light is blocked out, it appears as a narrow, red ring around the Sun. The red from the chromosphere is also visible in prominences when they project from the Sun. The temperature on the chromosphere is about 6000 K.
The Corona:
The last layer of the Sun is the corona, which is a collection of gases around the Sun. It is extremely hot, much hotter than the surface of the Sun. Like the chromosphere, it can only be seen during a solar eclipse with the naked eye or with a coronagraph. Scientists do not know while the corona is as hot as it is. Because of the very high temperatures, the corona emits high energy radiation and can be observed in X-rays. The Earth's atmosphere absorbs X-rays, but satellites above the atmosphere, such as the Yohkoh spacecraft, can observe the Sun in these wavelengths.
The Sun is a star, a hot ball of glowing gases at the heart of our solar system. With a mass of 1.989E30 kg, a diameter of 1,390,000 km and a surface temperature of 5800 K, it is the biggest object to be found in our solar system.
The Sun is made up of 6 parts:
The Core:
The core is the very centre of the Sun. It has an average temperature of 15,600,000 K and is the source of the star’s energy. Because of the core’s immense heat and the material in the core being so dense, it creates an environment just right for nuclear reactions to occur. The core is about 347,500 km in diameter.
In the core, the intense heat destroys the internal structure of an atom and therefore all atoms are broken down into their constituent parts. Neutrons are the first to leave the core as they do not have an electrical charge therefore, they don’t react to the surrounding medium. The protons and the electrons remain in the core and drive the reactions which fuel the Sun, together making plasma. The high temperature provides the protons and electrons with a large amount of thermal energy and as a result they move around quite quickly. This motion, combined with the high density of the plasma, causes the particles to continuously slam into one another creating nuclear reactions. It is the fusion of these particles that provides the energy source for the Sun.
The Radiative Zone:
The radiation zone is the next layer to the Sun, which surrounds the core. It is about 70% of the Sun’s radius. Inside the radiative zone, the energy generated by nuclear fusion in the core moves outward as electromagnetic radiation. This radiation does not take a straight path to the radiative zone’s edges, more following a random path inside the zone before making its way to the zone’s surface.
The Convection Zone:
The convection zone makes up the outer shell of the Sun. Here is the energy flows much faster than the radiative zone because of the process of convection. Hotter gas coming from the radiative zone expands and rises through the convective zone. This is because the convective zone is cooler than the radiative zone and therefore less dense. As the gas rises in the convection zone, it cools and begins to sink down again. As it falls to the top of the radiative zone, it heats up and begins to rise again. This process repeats, creating convection currents and the visual effect of boiling on the Sun's surface.
The Photosphere:
The next layer of the Sun is the photosphere, which actually is part of the Sun’s atmosphere. The photosphere is a very thin layer in comparison with the rest of the Sun. It is the only part of the Sun that we can actually see when looking at it from Earth, because the photosphere is where the light is emitted. The photosphere actually absorbs much of the light from the Sun because of its opaqueness. In the photosphere, granulation, supergranulation, faculae, and sunspots are found.
The Chromosphere:
The chromosphere is a narrow layer above the photosphere that rises in temperature with height. It is about 2500 km thick and is normally not visible with the naked eye because of the light from the photosphere being much stronger. However, during a solar eclipse when this light is blocked out, it appears as a narrow, red ring around the Sun. The red from the chromosphere is also visible in prominences when they project from the Sun. The temperature on the chromosphere is about 6000 K.
The Corona:
The last layer of the Sun is the corona, which is a collection of gases around the Sun. It is extremely hot, much hotter than the surface of the Sun. Like the chromosphere, it can only be seen during a solar eclipse with the naked eye or with a coronagraph. Scientists do not know while the corona is as hot as it is. Because of the very high temperatures, the corona emits high energy radiation and can be observed in X-rays. The Earth's atmosphere absorbs X-rays, but satellites above the atmosphere, such as the Yohkoh spacecraft, can observe the Sun in these wavelengths.
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The Sun: Sun Spots,
Solar Flares, Prominences, Solar Winds and the Solar Cycle:
Sun Spots:
Sun spots are darker, cooler areas on the surface of the sun, found on the photosphere. Sun spots have temperatures of about 3,800 degrees K. They look dark only in comparison with the brighter and hotter regions of the photosphere around them. Sun spots can reach up to up to 50,000 kilometres in diameter. Sun spots are caused by interactions with the Sun's magnetic field. Sunspots occur over regions of intense magnetic activity, and when that energy is released, solar flares and coronal mass ejections erupt from sunspots.
Sun Spots:
Sun spots are darker, cooler areas on the surface of the sun, found on the photosphere. Sun spots have temperatures of about 3,800 degrees K. They look dark only in comparison with the brighter and hotter regions of the photosphere around them. Sun spots can reach up to up to 50,000 kilometres in diameter. Sun spots are caused by interactions with the Sun's magnetic field. Sunspots occur over regions of intense magnetic activity, and when that energy is released, solar flares and coronal mass ejections erupt from sunspots.
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Solar Flares:
Solar flares are defined as a sudden, rapid and intense variation in brightness. These occur when magnetic energy that has built up in the solar atmosphere is suddenly released. The radiation that is emitted spans across virtually the entire electromagnetic spectrum, from radio waves at the long wavelength end, through optical emission to x-rays and gamma rays at the short wavelength end. The amount of energy released in a solar flare is the equivalent of millions of 100-megaton hydrogen bombs exploding at the same time. The first solar flare recorded in astronomical literature was on September 1, 1859. Two scientists, Richard C. Carrington and Richard Hodgson, were independently observing sunspots at the time, when they viewed a large flare in white light.
Solar flares are defined as a sudden, rapid and intense variation in brightness. These occur when magnetic energy that has built up in the solar atmosphere is suddenly released. The radiation that is emitted spans across virtually the entire electromagnetic spectrum, from radio waves at the long wavelength end, through optical emission to x-rays and gamma rays at the short wavelength end. The amount of energy released in a solar flare is the equivalent of millions of 100-megaton hydrogen bombs exploding at the same time. The first solar flare recorded in astronomical literature was on September 1, 1859. Two scientists, Richard C. Carrington and Richard Hodgson, were independently observing sunspots at the time, when they viewed a large flare in white light.
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Prominences:
Solar prominences are arcs of gas that erupt from the surface of the Sun. Prominences can loop hundreds of thousands of miles out into space. Prominences are held above the Sun's surface by strong magnetic fields and can last for many months. At some time in their existence, most prominences will erupt, spewing enormous amounts of solar material into space.
Solar prominences are arcs of gas that erupt from the surface of the Sun. Prominences can loop hundreds of thousands of miles out into space. Prominences are held above the Sun's surface by strong magnetic fields and can last for many months. At some time in their existence, most prominences will erupt, spewing enormous amounts of solar material into space.
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Solar Winds:
Solar winds are continuous stream of ions (electrically charged particles) that are given off by magnetic anomalies on the Sun. Solar wind is emitted where the Sun's magnetic field loops out into space instead of looping back into the Sun. These magnetic anomalies in the Sun's corona are called coronal holes which can last for months or even years. It takes the solar wind about 4.5 days to reach Earth; it has a velocity of about 400 km/sec. Solar winds affect the entire Solar System, including buffeting comets' tails away from the Sun, causing auroras on Earth (and some other planets), the disruption of electronic communications on Earth and more.
Solar winds are continuous stream of ions (electrically charged particles) that are given off by magnetic anomalies on the Sun. Solar wind is emitted where the Sun's magnetic field loops out into space instead of looping back into the Sun. These magnetic anomalies in the Sun's corona are called coronal holes which can last for months or even years. It takes the solar wind about 4.5 days to reach Earth; it has a velocity of about 400 km/sec. Solar winds affect the entire Solar System, including buffeting comets' tails away from the Sun, causing auroras on Earth (and some other planets), the disruption of electronic communications on Earth and more.
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The Solar Cycle:
The amount of magnetic flux that rises up to the Sun's surface varies with time in a cycle called the solar cycle. This cycle lasts 11 years on average. Near the minimum of the solar cycle, it’s rare to see sunspots on the Sun, and the spots that do appear are very small and short-lived. During the "solar maximum", there will be sunspots visible on the Sun almost all the time; often there are more than 100 spots visible at a time. Some of those spots will be very large, nearly up to 50,000 km in diameter and can last several weeks.
The amount of magnetic flux that rises up to the Sun's surface varies with time in a cycle called the solar cycle. This cycle lasts 11 years on average. Near the minimum of the solar cycle, it’s rare to see sunspots on the Sun, and the spots that do appear are very small and short-lived. During the "solar maximum", there will be sunspots visible on the Sun almost all the time; often there are more than 100 spots visible at a time. Some of those spots will be very large, nearly up to 50,000 km in diameter and can last several weeks.
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The Implication for Earth:
Solar activity can affect Earth and the whole solar system. With solar winds for example, they have been known to send the astronauts of the International Space Station running for cover, damage satellites, force airlines to change flight paths and disruption of electronic communications on Earth. Solar activity is not directly harmful to us humans or any other life form on Earth because of our magnetic field which protects us for the harmful effects.
The Sun Screen Debate:
The Sun Screen debate is about the choice to wear sun screen which may or may not contain nanoparticles and therefore affect your chances of getting some types of cancers or not wearing sunscreen and just relying on basic sun safety.
What are nanoparticles?
Nano particles are particles with one or more dimension less than 100nm. There is many various health and environmental concerns about nanoparticles because of their ability to penetrate cells in organisms, and their interactions with biological systems are still relatively unknown.
Why are people worried about nanoparticles in sunscreen?
Several years ago, after Colorbond painted roofing showed accelerated deterioration in fingerprint-shaped patches from sunscreen used by builders. Research then published by Colorbond manufacturer BlueScope Steel in 2008 confirmed that certain nanoparticles in titanium dioxide-based sunscreens were the culprit. Other lab tests have indicated that nanoparticles of zinc oxide and titanium dioxide may create free radicals that cause damage to cellular DNA and mitochondria, particularly in the presence of UV light. Free radical damage may also lead to cancer.
Solar activity can affect Earth and the whole solar system. With solar winds for example, they have been known to send the astronauts of the International Space Station running for cover, damage satellites, force airlines to change flight paths and disruption of electronic communications on Earth. Solar activity is not directly harmful to us humans or any other life form on Earth because of our magnetic field which protects us for the harmful effects.
The Sun Screen Debate:
The Sun Screen debate is about the choice to wear sun screen which may or may not contain nanoparticles and therefore affect your chances of getting some types of cancers or not wearing sunscreen and just relying on basic sun safety.
What are nanoparticles?
Nano particles are particles with one or more dimension less than 100nm. There is many various health and environmental concerns about nanoparticles because of their ability to penetrate cells in organisms, and their interactions with biological systems are still relatively unknown.
Why are people worried about nanoparticles in sunscreen?
Several years ago, after Colorbond painted roofing showed accelerated deterioration in fingerprint-shaped patches from sunscreen used by builders. Research then published by Colorbond manufacturer BlueScope Steel in 2008 confirmed that certain nanoparticles in titanium dioxide-based sunscreens were the culprit. Other lab tests have indicated that nanoparticles of zinc oxide and titanium dioxide may create free radicals that cause damage to cellular DNA and mitochondria, particularly in the presence of UV light. Free radical damage may also lead to cancer.
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Radiation:
UVC: Short-wave ultraviolet radiation, in the "C" band has been used for over 100 years. UV-C (UVC) is also referred to as UVGI (ultraviolet germicidal irradiation). UVC penetrates the outer structure of the cell and alters the DNA molecule, preventing replication and causing cell death. UVB: UVB, the chief cause of skin reddening and sunburn, tends to damage the skin's more superficial epidermal layers. It plays a key role in the development of skin cancer and a contributory role in tanning and photo-aging. UVA: Although they are less intense than UVB, UVA rays are 30 to 50 times more prevalent. UVA, which penetrates the skin more deeply than UVB, has long been known to play a major part in skin aging and wrinkling (photoaging). UVA also contributes to and may even initiate the development of skin cancers. Visble light: Visible light waves are the only electromagnetic waves we can see. We see these waves as the colors of the rainbow. Each color has a different wavelength. Red has the longest wavelength and violet has the shortest wavelength. When all the waves are seen together, they make white light. IR : Infrared (IR) light is electromagnetic radiation with longer wavelengths than those of visible light, extending from the nominal red edge of the visible spectrum. |
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% by Sun
< 1% <5% 95% Of all UV 43% About 49% |
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Effects on human skin
DNA Damage DNA damage and skin cancer Skin aging/ sun burn/ leads to skin cancer None known Heat sensation |
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Visible to humans
No No No Yes No |