The Burning Star
The sun is a star located in the centre of our Solar System and is classified as a 'yellow dwarf star.' Scientists believe it is approximately 4.5 billion years old. It is perfectly spherical with a diameter of 1,391,000 kilometres making it about 109 times that of Earth. The Sun is made of mainly hydrogen and burns up to 4 million tonnes of this gas per second. The Sun makes up 99.86% of the Solar System's combined mass. It is made up of hot plasma and has an average surface temperature of 5700°C.
The sunlight we receive on Earth today was formed in the core of the Sun 30,000 years ago by a process called 'Nuclear Fusion'. The energy of this sunlight spent the majority of time passing through the dense atoms that make up the sun and then just 8 minutes to reach Earth, which is 149.6 million kilometres from the Sun.
Birth Of our Sun
Our Sun was brought into existence by a voilent explosion of supernovas. This was the same time in which our Solar System was born. After the explosion, large amounts of debris and dust were left behind forming an enormous dark gas cloud, called a 'Nebula.' During this time, parts of the cloud experienced a gravitational collapse causing the dust and debris to compress and form what is called a 'large interstellar cloud.' Inside this cloud multiple dense cores were formed. These rotating balls come together to form a gas globule, a small round particle of substance, thus completing the birth of our Sun.
The sun is a star located in the centre of our Solar System and is classified as a 'yellow dwarf star.' Scientists believe it is approximately 4.5 billion years old. It is perfectly spherical with a diameter of 1,391,000 kilometres making it about 109 times that of Earth. The Sun is made of mainly hydrogen and burns up to 4 million tonnes of this gas per second. The Sun makes up 99.86% of the Solar System's combined mass. It is made up of hot plasma and has an average surface temperature of 5700°C.
The sunlight we receive on Earth today was formed in the core of the Sun 30,000 years ago by a process called 'Nuclear Fusion'. The energy of this sunlight spent the majority of time passing through the dense atoms that make up the sun and then just 8 minutes to reach Earth, which is 149.6 million kilometres from the Sun.
Birth Of our Sun
Our Sun was brought into existence by a voilent explosion of supernovas. This was the same time in which our Solar System was born. After the explosion, large amounts of debris and dust were left behind forming an enormous dark gas cloud, called a 'Nebula.' During this time, parts of the cloud experienced a gravitational collapse causing the dust and debris to compress and form what is called a 'large interstellar cloud.' Inside this cloud multiple dense cores were formed. These rotating balls come together to form a gas globule, a small round particle of substance, thus completing the birth of our Sun.
Structure
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The Sun is currently classified as a yellow dwarf star. It has 6 layers:
The Core: The Sun's core, at approximately 15 million °C, is found in the centre of the star. It is constantly undergoing a process called 'nuclear fusion.'. This is when, due to high pressure levels, the Sun turns four hydrogen nuclei into a single helium nucleus producing a large amount of energy. The hydrogen burning process, emits gamma rays and neutrinos (particles with no charge and almost no mass).
The Radiative Zone: Is the first layer out from the core where radiation is released. The radiation diffuses outwards. The zones temperature ranges from 15 million °C to 1 million °C.
It can take photons (a particle representing a quantum of light or other electromagnetic radiation) thousands of years to pass through the radiative zone.
The Convective Zone: In this next layer, photons continue to pass through the layers via convection. The temperature in the Convective Zone ranges from 1 million °C to 6,000 °C.
The Photosphere: This is the first layer in the Sun's atmosphere. This part is visible to us because it emits light at visible wavelengths. This layer is approximately 500km thick with a temperature of about 5,500 °C.
The Chromosphere: This layer of the Sun has a temperature that ranges from 6,000 °C to 50,000 °C . It is a few thousand kilometers thick and appears red because the hydrogen atoms are emitting radiation near the red part of the visible spectrum.
The Corona: The outer layer of the Sun's atmosphere is called the Corona. The corona extends for millions of kilometres with temperatures reaching 1 million °C. It is not unusual for holes to appear in this layer. These holes occur where the Sun's magnetic field bursts out into space.
Solar Flares
A solar flare occurs when a magnetic storm on the Sun causes an eruption on it's surface. These eruptions release huge amounts of high-energy particles and extremely hot gases. These particles are released thousands of kilometres from the Sun's surface. The solar flares were first observed in 1859 by scientist, Lord Richard C. Carrington. While observing the Sun through his telescope, Carrington wrote that he saw "two patches of intensely bright and white light" near a large group of sunspots. Just a few seconds later, the flare disappeared.
The Core: The Sun's core, at approximately 15 million °C, is found in the centre of the star. It is constantly undergoing a process called 'nuclear fusion.'. This is when, due to high pressure levels, the Sun turns four hydrogen nuclei into a single helium nucleus producing a large amount of energy. The hydrogen burning process, emits gamma rays and neutrinos (particles with no charge and almost no mass).
The Radiative Zone: Is the first layer out from the core where radiation is released. The radiation diffuses outwards. The zones temperature ranges from 15 million °C to 1 million °C.
It can take photons (a particle representing a quantum of light or other electromagnetic radiation) thousands of years to pass through the radiative zone.
The Convective Zone: In this next layer, photons continue to pass through the layers via convection. The temperature in the Convective Zone ranges from 1 million °C to 6,000 °C.
The Photosphere: This is the first layer in the Sun's atmosphere. This part is visible to us because it emits light at visible wavelengths. This layer is approximately 500km thick with a temperature of about 5,500 °C.
The Chromosphere: This layer of the Sun has a temperature that ranges from 6,000 °C to 50,000 °C . It is a few thousand kilometers thick and appears red because the hydrogen atoms are emitting radiation near the red part of the visible spectrum.
The Corona: The outer layer of the Sun's atmosphere is called the Corona. The corona extends for millions of kilometres with temperatures reaching 1 million °C. It is not unusual for holes to appear in this layer. These holes occur where the Sun's magnetic field bursts out into space.
Solar Flares
A solar flare occurs when a magnetic storm on the Sun causes an eruption on it's surface. These eruptions release huge amounts of high-energy particles and extremely hot gases. These particles are released thousands of kilometres from the Sun's surface. The solar flares were first observed in 1859 by scientist, Lord Richard C. Carrington. While observing the Sun through his telescope, Carrington wrote that he saw "two patches of intensely bright and white light" near a large group of sunspots. Just a few seconds later, the flare disappeared.
Solar Wind
The solar wind is a continuous stream of ions (electrically charged particles) that are emitted by the Sun. The wind is released where the Sun's magnetic field loops out into space instead of refracting back into the Sun. These magnetic anomalies in the Sun's corona, outer most layer, are called 'coronal holes.' When viewing these holes in X-ray photographs, they appear as black areas. Coronal holes can last for months or years.
"It takes the solar wind about 4.5 days to reach Earth; it has a velocity of about 250 miles/sec (400 km/sec). Since the particles are emitted from the Sun as the Sun rotates, the solar wind blows in a pinwheel pattern through the solar system. The solar wind affects 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, pushing spacecraft around, etc."
(Extracted from: http://www.enchantedlearning.com/subjects/astronomy/sun/prominences.shtml)
Sun Spots
Sunspots are cool, dark marks on the sun's surface that are visible from Earth. They can appear in many different shapes and sizes and are often seen in groups. These spots are much larger than the Earth. Some have even been found to have a diameter 10 times that of Earth. Individual sunspot will only last for one to two weeks. However, a group of sunspots follows an 11 year cycle. This 'sunspot cycle' was discovered in 1843 by S. Heinrich Schwabe.
Solar Eclipse
A solar eclipse occurs when the Moon comes between the viewing path of the Sun from the Earth. The longest solar eclipses happens when the Earth is at 'aphelion,' meaning it as at its furthest point from the Sun, and the Moon is at 'perigee,' at its closest point to the Earth, at the same time. Because of this the Sun appears smaller and the Moon appears larger. Therefore, when the Moon moves in front of the Sun it blocks our view of the sun.
There are three types of eclipses, Partial Solar Eclipse, Total Solar Eclipse and Annular Eclipse. An Annular Eclipse occurs when the sun appears like an 'annulus,' which means 'little ring' in Latin. This is because the corona (upper most part of the Sun's atmosphere) becomes visible to us on Earth. Normally, the photosphere's extremely bright light blocks the corona and we don't see it. However, when an Annular Eclipse occurs, the moon is large enough to block the Sun's photosphere, causing the corona to be seen in a ring like shape. Total Eclipse's occurs when the Sun's solar disc is completely blocked by the Moon. This type of Eclipse is can only be seen in some parts of the world. It doesn't last very long, approximately 8 minutes. A Partial Eclipse occurs when the Moon covers only part of the solar disc.
Why is the Sun important?
The Sun is Earth’s main source of energy, heat and light. It is these three things that makes Earth habitable (livable). Sunlight is responsible for starting a process called 'photosynthesis,' which allows a plant convert light energy from the Sun into chemical energy. This process starts the life cycle for all living things on Earth. It is then continued by (for example) bugs eating the plants, animals eating the bugs and humans eating the animals. Sunlight gives living organisms their food making it possible for them to survive.
The Sun also provides the warmth for survival. Without the Sun it would be impossible for life to exist on Earth as it would be too cold, have no food and be in complete darkness. Everything biotic (living) on Earth in some why, shape or form depends greatly on the Sun.
Past Theories
Everything in the Solar System is held in orbit around the Sun by its magnetic field and gravitational pull. In a past theory called 'The Geocentric Theory' it was believed that the Earth was the centre of the universe and that everything orbited it. The Geocentric Theory was very popular in China and ancient Greece.
This theory was believed to be proven because from Earth it appears as if the stars, sun, and planets are revolving around the Earth each day. Also because during this time they believed the Earth was not moving, therefore, all other objects must be orbiting around it.
Geocentrism was replaced by the 'Heliocentric Theory' in the 16th century. This theory states that all things orbited the Sun and was first proposed by Nicolaus Copernicus, a mathematician and astronomer. Johannes Kepler elaborated this theory in the next century by expanding the model to include the orbit route of the planets. He discorded these orbits using his telescope and then presented his theory to Galileo Galilei, another leading astronomer.
Later, observations by Bessel, William Herschel and other astronomers had discovered that the sun was not the centre of the universe but rather that is was a part of a galaxy.
Will the Sun die?
The Sun will one day begin to die. It will start to burn out as it burns off all its nuclear fuel (hydrogen). So far, the Sun has used up half of this fuel. In approximately 5 million years from now, it will use up all the hydrogen. The sun expands as it grows older but when it runs out of gas it will contract causing the outer layers to expand, cool and become less bright. At this stage the Sun will be classified as a 'red giant.'
The outer layers will continue to expand. During this time, the helium atoms still in the core will fuse together, forming carbon atoms and release energy. The outer layers will then start to drift off into space, exposing the core. This means the Sun is a 'planetary nebula.' The remainder of the Sun will cool and shrink resulting in it being only a few kilometres in diameter