Can you imagine life without the sun? Where would we be without it? The Sun is vital for our existence as it provides Earth with heat and light (and those warm Summer days that we all love). Making up 98% of the solar system’s matter, it is the largest object in our solar system. Due to it's enormous size compared to everything else, it easily holds on to everything else, causing things to orbit around it.
Layers of the Sun
As displayed above, the Sun consists of six layers:
The Core
The very inside of the Sun is called the core. This is where the Sun gathers its energy. The temperature of this layer is about 15 600 000° K. Because of the extreme temperature in this layer, atoms are constantly colliding and being broken down. This causes fusion of hydrogen atoms to occur. The energy produced by this fuels the Sun, allowing to provide heat and light for us here on Earth. This energy is in the form of photons (gamma rays), which is a form of electromagnetic radiation.
The Radiation Zone
The layer surrounding the core is the radiation zone. This layer's temperature is 7 million° K. As the photons that are made in the core are so incredibly fast (as fast as the speed of light), they bounce off of each other as they make their way through the radiation zone. Due to the constant collisions, it can take 100 000 years for the photons to make their way through the radiation zone.
The Convection Zone
The layer after the radiation zone is the convection zone. This layer's temperature is about 2 million° K. In the convection zone, the transfer of energy occurs much faster than in the radiation zone. Because this layer is so much cooler, the hot gases coming from the inner layers are caused to grow in size and ascend to the top of the convection zone. When the energy reaches this point it is transferred into the next layer. Whilst the gases are rising their temperature starts to drop, causing them to lower back into the radiation zone. They then repeat the process and create convection currents. This is the reason that the surface of the sun appears to be boiling.
The Photosphere
The layer after the convection zone is the photosphere. This layer is about 5800° K. The photosphere is commonly referred to as the Sun's surface. However, as the Sun is a ball of gases, it does not have an actual surface. This is where the Sun’s light is emitted from. This causes it to be the only layer of the Sun that can be seen by us on Earth. This layer is home to sunspots (for more information, see below).
The Chromosphere
The chromosphere is the slim layer above the photosphere. The only time that the chromosphere can be viewed from Earth is during a solar eclipse, when the moon blocks out the photosphere. This layer hosts solar flares and prominences (for more information, see below). The temperature of this layer is 4500° K.
The Corona
The area around the sun is called the Corona. It extends to over one million km from the surface. Its temperature can reach up to 2 million° K. The corona emits X-ray radiation. Just like the chromosphere, the only time the corona can be seen from Earth is during a solar eclipse.
The Core
The very inside of the Sun is called the core. This is where the Sun gathers its energy. The temperature of this layer is about 15 600 000° K. Because of the extreme temperature in this layer, atoms are constantly colliding and being broken down. This causes fusion of hydrogen atoms to occur. The energy produced by this fuels the Sun, allowing to provide heat and light for us here on Earth. This energy is in the form of photons (gamma rays), which is a form of electromagnetic radiation.
The Radiation Zone
The layer surrounding the core is the radiation zone. This layer's temperature is 7 million° K. As the photons that are made in the core are so incredibly fast (as fast as the speed of light), they bounce off of each other as they make their way through the radiation zone. Due to the constant collisions, it can take 100 000 years for the photons to make their way through the radiation zone.
The Convection Zone
The layer after the radiation zone is the convection zone. This layer's temperature is about 2 million° K. In the convection zone, the transfer of energy occurs much faster than in the radiation zone. Because this layer is so much cooler, the hot gases coming from the inner layers are caused to grow in size and ascend to the top of the convection zone. When the energy reaches this point it is transferred into the next layer. Whilst the gases are rising their temperature starts to drop, causing them to lower back into the radiation zone. They then repeat the process and create convection currents. This is the reason that the surface of the sun appears to be boiling.
The Photosphere
The layer after the convection zone is the photosphere. This layer is about 5800° K. The photosphere is commonly referred to as the Sun's surface. However, as the Sun is a ball of gases, it does not have an actual surface. This is where the Sun’s light is emitted from. This causes it to be the only layer of the Sun that can be seen by us on Earth. This layer is home to sunspots (for more information, see below).
The Chromosphere
The chromosphere is the slim layer above the photosphere. The only time that the chromosphere can be viewed from Earth is during a solar eclipse, when the moon blocks out the photosphere. This layer hosts solar flares and prominences (for more information, see below). The temperature of this layer is 4500° K.
The Corona
The area around the sun is called the Corona. It extends to over one million km from the surface. Its temperature can reach up to 2 million° K. The corona emits X-ray radiation. Just like the chromosphere, the only time the corona can be seen from Earth is during a solar eclipse.
Sunspots
From our eyes on Earth, the sun looks like a smooth white ball without an imperfection. However this is not the case. On the photosphere of the Sun, one can sometimes see a ‘sunspot’. These appear as dark spots due to them being cooler than the surrounding region. Sunspots are only temporary, as after a while they return to the solar interior. According to Kenneth R. Lang, ‘large sunspots are as big as the Earth and contain magnetic fields that are thousands of times stronger than the Earth’s magnetic field’(cited in What are sunspots, and do they have an effect on the Earth's weather? 2012). Occasionally, a sunspot becomes so big that at sunrise or sunset, it can be seen by the naked eye. The existence of sunspots makes it impossible for the sun to glow at its full potential. Sunspots have an influence on Earth as when there is frequent sunspot activity, a solar wind occurs (see below).
The Solar Cycle
The graph below shows the solar cycle. The vertical axis represents the number of sunspots found in the year. The horizontal axis represents the year.
Solar Flares
A solar flare is ‘an explosion on the Sun that happens when energy stored in twisted magnetic fields (usually above sunspots) is suddenly released’ (Spaceweather.com 2010). Solar flares are classified into three categories:
- X-class flares – these are big and can result in worldwide radio blackouts and extreme radiation storms.
- M-class flares – these are medium-sized and can result in minor radio blackouts in Earth’s polar regions.
- C-class flares – these are small and result in very few noticeable consequences on Earth.
Solar Prominences
According to Wikipedia (Solar Prominence 2012), a solar prominence is ‘a large, bright feature extending outward from the Sun’s surface, often in a loop shape’. Prominences come from the Sun’s photosphere and continue into the corona. One is formed in about a day, and may exist for many months. Solar prominences release solar flares, which have an affect on Earth (see above for more information).
Solar Winds
A solar wind (also known as a coronal mass ejection) is ‘a flow of charged particles that travels from the Sun out into the solar system’ (Astronomical Glossary 2012). These solar winds cause an increased amount of energy to travel to the poles of the Earth. This is why in the poles we see beautiful auroras.
The Electromagnetic Spectrum
Electromagnetic radiation is a type of energy. It is measured by the wavelength.
Ultraviolet Radiation
Ultraviolet (UV) light is a type of radiation that the sun emits. Although we cannot see or feel UV radiation, it does affect us on Earth majorly. There are three types of UV radiation:
- UVA – Most people will constantly be exposed to this type of UV ray in their lifetime. UVA causes skin aging and wrinkling. Too much exposure to this can cause sunburn and skin cancer. However, many of us continuously seek it out, as it provides us with a tan. A tan results from the skin being harmed. The skin then darkens as an attempt to prevent further injury.
- UVB – This type is the main cause of skin cancer and sunburn. The Ozone layer prevents it from reaching us, however there are holes in this layer.
- UVC – This is the most extreme and dangerous type of UV ray. Luckily, the Ozone layer stops all UVC so that none of it reaches us.
The Sunscreen Debate
Recently there has been an ongoing debate about the possibility that applying sunscreen does more harm than good, as it may cause cancer. It all has to do with whether or not sunscreen and other cosmetics contain nanoparticles. According to choice.com.au ‘Nanoparticles are particles with one or more dimension less than 100 nanometers’ (Choice 2012). Because of their extremely tiny size, they are able to penetrate skin cells. The reactions that take place when this occurs are unknown, which causes various health concerns. Scientific tests have taken place, and have shown that, when an object is subjected to UV rays, and it has been coated with a substance that contains nanoparticles, the object has been destroyed. These tests were done on painted surfaces and DNA.
In my opinion, sunscreen is not safe to use. However, constant exposure to the sun is also highly dangerous. The best thing to do is to cover up when in the sun, and find shade if possible.
In my opinion, sunscreen is not safe to use. However, constant exposure to the sun is also highly dangerous. The best thing to do is to cover up when in the sun, and find shade if possible.