The Sun
The sun is only one of billions of stars. It takes the sun 27 days to rotate on its axis. The sun is made up of 92% hydrogen, 7% helium and 1% other gases. The sun is the largest mass in our solar system. The diameter of the sun, 1 400 00 kilometres, makes it big enough to fit 1 million Earths inside the sun. It appears yellow in colour due to its surface temperature. The density of the sun is 1400 kg/m3. Most of the suns mass, roughly 90%, is found in the interior half of the sun.
The Process of Nuclear Fusion
Nuclear fusion is the process that powers active stars, like the sun. The sun fuses hydrogen nuclei into helium to create energy. It is estimated that the sun fuses roughly 620 metric tons of hydrogen every second.
The sun has many layers. They are shown in the diagram below:
The sun has many layers. They are shown in the diagram below:
The suns core is approximately 15 000 000°C. The core is the site of nuclear fusion in the sun. The energy from the core travels outwards through the radiant zone. This happens by the transfer of energy from one molecule to another. Heated gases move the energy from the radiant zone through to the convection zone. In the convection zone the gases start to cool. This causes them to sink back down to the radiant zone. The photosphere is approximately 500 kilometres thick and is the surface layer of the sun. The thin layer of gas that surrounds the photosphere is called the chromosphere. The chromosphere is 2500 kilometres thick. The corona is another layer of gas that extends a long way outside of the sun. It is heated by magnetic energy from the sun.
The Importance of the Sun
The sun is the only star in our Solar System. It provides all the energy that supports life on Earth. This energy it absorbed by plants through photosynthesis. Animals (and humans) eat these plants and the energy is transferred from the plant. Humans then eat these animals and the energy is transferred to the human from the animal. The sun supplies daylight to Earth. The sun doesn’t move but the Earths position relative to it does. The sun supplies heat which maintains a liveable climate on Earth. There would be no changes in season without the sun. It takes the Earth 365 days (one year) to orbit the Sun. When the northern hemisphere is pointed towards the sun Australia experiences winter. When the southern hemisphere is pointed towards the sun Australia experiences summer. Due to the Earth’s distance from the sun, one astronomical unit or 150 000 000 kilometres, we have the perfect temperature that allows water to condense and rain to fall. The most important function of the sun is its gravitational pull on the Earth, which keeps it in orbit – stopping the Earth from flying off into space.
Features
SUNSPOTS
Sunspots are dark spots on the surface on the sun; they appear dark because they are cooler than the photosphere surrounding the sun. The temperature in the centre of a sunspot drops by around 5700K. Sunspots aren’t really dark; they are just dark in comparison to the bright background of the sun. They generally appear in pairs with magnetic fields between them. Sunspots last several day but large ones can last several weeks. Sunspots reach a maximum occurrence every 11 years. There is also a suggestion of a 55 to 57 year cycle. The diameter of the largest observed sunspots were approximately 50 000 km which made them easy enough to see with the naked eye.
Sunspots are dark spots on the surface on the sun; they appear dark because they are cooler than the photosphere surrounding the sun. The temperature in the centre of a sunspot drops by around 5700K. Sunspots aren’t really dark; they are just dark in comparison to the bright background of the sun. They generally appear in pairs with magnetic fields between them. Sunspots last several day but large ones can last several weeks. Sunspots reach a maximum occurrence every 11 years. There is also a suggestion of a 55 to 57 year cycle. The diameter of the largest observed sunspots were approximately 50 000 km which made them easy enough to see with the naked eye.
SOLAR FLARES
A solar flare is a sudden change in the brightness of the sun. Solar flares happen when magnetic energy built up in the solar atmosphere is suddenly released. Solar flares usually happen over the top of a sun spot due to their magnetic fields. The most powerful solar flare was observed on September 1st, 1859, and was called The Solar Storm of 1859 or the Carrington Event. It was reported by Richard Carrington, a British astronomer and an observer named Richard Hodgson. Currently, there are methods for predicting solar flares, but they are problematic as there is no certain indication that an active spot on the sun will cause a solar flare.
A solar flare is a sudden change in the brightness of the sun. Solar flares happen when magnetic energy built up in the solar atmosphere is suddenly released. Solar flares usually happen over the top of a sun spot due to their magnetic fields. The most powerful solar flare was observed on September 1st, 1859, and was called The Solar Storm of 1859 or the Carrington Event. It was reported by Richard Carrington, a British astronomer and an observer named Richard Hodgson. Currently, there are methods for predicting solar flares, but they are problematic as there is no certain indication that an active spot on the sun will cause a solar flare.
SOLAR WINDS
A solar wind is a stream of charged particles, mostly electrons and protons, which are ejected from the sun in all directions. Over time the temperature and speed of these particles vary. It usually takes about a week for the particles from a solar wind to travel to the Earth. When these particles reach the Earth they get trapped. Solar winds are thought to be responsible for the tails of comets, along with the Sun’s radiation.
A solar wind is a stream of charged particles, mostly electrons and protons, which are ejected from the sun in all directions. Over time the temperature and speed of these particles vary. It usually takes about a week for the particles from a solar wind to travel to the Earth. When these particles reach the Earth they get trapped. Solar winds are thought to be responsible for the tails of comets, along with the Sun’s radiation.
ECLIPSE
Eclipses are caused by shadows being cast on objects. There are two types of eclipses- solar eclipses and lunar eclipses.
Solar Eclipse
A solar eclipse happens when the moon blocks the light from the sun from reaching the Earth. This causes a shadow to be cast onto the Earth. Once a month the moon passes between the Earth and the sun, the moon and sun don’t always line up completely but when they do it causes a total solar eclipse. The darkest are of the moon’s shadow is called the umbra and is where the moon is completely blocking out the suns light.
Eclipses are caused by shadows being cast on objects. There are two types of eclipses- solar eclipses and lunar eclipses.
Solar Eclipse
A solar eclipse happens when the moon blocks the light from the sun from reaching the Earth. This causes a shadow to be cast onto the Earth. Once a month the moon passes between the Earth and the sun, the moon and sun don’t always line up completely but when they do it causes a total solar eclipse. The darkest are of the moon’s shadow is called the umbra and is where the moon is completely blocking out the suns light.
Lunar Eclipse
A lunar eclipse occurs when the Earth blocks the light from the sun from reaching the moon, casting a shadow onto the moon. The moon only reflects light from the sun, it doesn’t emit its own light. A lunar eclipse can only happen on the night of a full moon.
A lunar eclipse occurs when the Earth blocks the light from the sun from reaching the moon, casting a shadow onto the moon. The moon only reflects light from the sun, it doesn’t emit its own light. A lunar eclipse can only happen on the night of a full moon.
The Fate of Our Sun
Our sun is estimated to be 4.5 billion years old. At this point in time it has almost used up half of its hydrogen or nuclear fuel. In approximately5 billion years the sun will begin to die. As it grows old it will expand, engulfing most, if not all of the planets in our solar system. As the core runs out of hydrogen and helium it will begin to contract and the outer layers will expand and become cooler and less bright. Our sun will become a red giant. As the outer layers continue to contract the helium atoms in the core will fuse together forming carbon atoms and releasing energy. At this stage the core will be stable as the carbon atoms can’t be compressed more. The outer layers will drift off into space forming a planetary nebula and exposing the core. Almost all of the suns mass will go to the nebula and the remaining sun will cool and shrink. The sun has now become a white dwarf- a stable star with no nuclear fuel left. The white dwarf will continue to radiate its left over heat for billions of years. When this heat runs out the sun will become a cold, dark black dwarf. At this point it is essentially a dead star.
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