The Sun
The sun is the closest star to Earth being 149 600 000 kms away. It has a diameter of 1 392 000km which is 109 times the size of Earth's diameter and has a mass of 1.989E30 kg The sun is 10 times the size of Jupiter; the largest planet in our solar system. This page covers the structure of the sun, sunspots, flares, prominences and solar winds.
Structure of the SunInner Structure: The inner structure of the sun consists of three layers; the core, radiation zone and convection zone.
Core - The core of our sun is the very centre layer. It is immensely hot with temperatures of more than 15 million degrees Kelvin (K). This heat destroys and breaks down the structure of atoms to protons (+), neutrons (neutral) and electrons (-). These move extremely fast and slam into each other and this causes them to fuse. It releases heat and light; this is called plasma. This is also where hydrogen is converted to helium. Radiation Zone - The radiation zone is the middle layer of the inner structure of the sun and reaches temperatures of up to 5 million K. When fusion occured in the core energy was created this reacts with a large amount of gamma rays which then passes through the radiation zone. This can take up to 170 thousand years. Convection Zone - The convection zone is the outermost layer of the internal structure of the sun. It reaches temperatures of up to 2 million K. It can also be known as the boiling zone. It takes up the final 30% of the sun's radius. The convection zone is named after the convection currents that travel in it. These currents carry energy towards the surface. Outer Structure:
Photosphere - The photosphere is the deepest layer of the sun that you can see. It is referred to as the surface of the sun because at the top of it the photons are finally able to escape. It is about 500km thick and has a temperature of roughly 5840 K. The gas is thick enough that you can not see through it and emits a continuous spectrum. Chronosphere - The chromosphere is a thin pink layer of the sun that is only 2000 - 3000km thick. As it moves away from the photosphere it's temperature rises. The chromosphere has a very low density therefore you see the emission lines of hydrogen which is what makes it appear pink. Corona - The corona is the final layer of the sun and can very rarely be seen. It is only visible during events such as total solar eclipses. It has very high temperatures of of one to two million K.The temperature of the corona is so hot because it has ions with many electrons removed from the atoms. The atoms collide with one another with such energy to eject electrons. This process is known as ionization. |
Sunspots
Galileo discovered that sunspots are regions on the sun's 'surface' that appear to be dark because they are cooler than the surrounding photosphere and do not emit much light. They are generally cooler by about 1500 K but they are still extremely hot at temperatures of up to 4500 K. The largest sunspots observed are about 50 000Km in diameter which mean that they are large enough to be seen by the human eye. They often appear in groups with as many as 100 per group. Although on average there are only about ten in a regular sunspot group. Galileo used the longer lasting sunspots to work out the rotation patterns of the sun. Not all parts of the sun rotate at the same rate because the sun is so gaseous.
Sunspot Diagram
This is a diagram displaying the variation in sunspot number each year from 1920 - 2010.
It also displays the Min and Max solar activity of sunspots.
This is a diagram displaying the variation in sunspot number each year from 1920 - 2010.
It also displays the Min and Max solar activity of sunspots.
Sun Flares
A solar flare is sudden intense burst of light and radiation from the sun's magnetic atmosphere. They are ejected thousands of miles from the surface of the Sun. his occurs when magnetic energy has built up in the solar atmosphere and then is suddenly released. This energy then travels at the speed of light and reaches Earth just eight minutes later. A part of the atmosphere called the ionosphere absorbs it. These flares are placed into three different categories by scientists depending on their brightness in the x-ray wavelengths; x-class, m-class and c-class. X-class flares are the biggest of the three and are major events that can even cause radio blackouts and long lasting radiation storms in the upper atmosphere. M-class flares are medium sized and generally only cause brief radio blackouts but they only affect the Earth's polar regions. Sometimes a minor radiation storm may also follow. C-class flares a by far the smallest and have very few noticable affects compared to the other two types.
Prominances
A prominence is an arc of gas that erupts from the surface of the sun. They can loop thousands of miles into space and are held there by strong magnetic fields. They can last for many months. At some point during the existence of a prominence it will erupt causing enormous amounts of solar material to be spewed into space. There are two types of solar prominence; active and quiescent. Active prominences erupt rapidly and have shorter lifetimes lasting from just several minutes to a few hours. However quiescent prominences emerge smoothly and subside much slower; they can be visible for several months.
Solar Winds
A solar wind is a continuous stream of electrically charged particles called ions. They are given off by magnetic anomalies on the sun such as coronal holes. A solar wind is caused when the sun's magnetic field loops out into space instead of back to the sun. In X-ray photographs of the sun, coronal holes appear to be black areas and they last for months if not years. A solar wind takes about 4.5 days to reach Earth and travels at a velocity of approximately 400km/sec. These winds affect the entire solar system and cause events such as buffeting comets' tails away from the sun, causing auroras on Earth (and other planets), the disruption of electronic communications on Earth, pushing spacecraft around and so forth.