The Sun
 We know the Sun as an intense radiant globe that warms and gives us light and life. The Sun is almost incredibly large; it sends out into space unbelievably great quantities of energy and influences and affects the Earth and us in many ways.
In this teachers’ resource we are going to have a look at what the Sun is, how it affects the Earth, and why and how we conduct research on this exciting star.
We shall also try to explain how the Sun and the rest of the solar system came into existence 4.6 billion years ago, and what destiny is awaiting us at some time in the far distant future.
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The place of the Sun in the solar system
 Are you interested in learning more about the solar system?
Our own globe is called “The blue planet”. Do you know why?
How to make a model of the solar system?
Here you may read about the Sun and the 8 planets.
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Early knowledge about the Sun
 Before the 1700-hundreds the most important questions within astronomy were about how space was built up, and whether the Sun or the Earth is in the centre of the universe.
Today we know that the Sun is in the centre of the solar system, but not at all in the centre of the universe.
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The structure of the Sun
 The Sun is a gigantic gas globe. It is so large that it could have contained 1 300 000 (1.3 million) globes the size of the Earth.
It is also very, very hot. In the outer parts of the Sun the gas is boiling.
It behaves in almost the same way as the water in a kettle does. Here we are going to look more closely at what happens.
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The outer layers of the Sun
 The outer layers of the Sun may be observed directly, but ordinarily it is only the thin, visible surface that may be studied in detail from the ground. With the space age quite new possibilities also arrived for studying the Sun in other types of radiation than visible light.
A number of strange and amazing phenomena take place in the outer layer of the Sun. Here we are going to look more closely at these phenomena.
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Solar activity
 The Sun is an active star – it boils, large clouds of gas are projected into space, large spots appear and disappear, faculae protrude thousands of kilometres out from the surface, explosions are as violent as if millions of atomic bombs were fired off and gigantic arches of hot gases lift hundreds of thousands of kilometres above the surface of the Sun. All these and a number of other phenomena are changing all the time.
This is called Sun activity.
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The mystery of the Northern lights
 Surrounded by the mystery of former times, this is at present the object of sound curiosity among most people and of deep interest to researchers.
Educational examples give insight into the research into the northern lights, popular belief and mystery, forms of northern lights and images.
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Solar eclipses
 The most magnificent solar phenomenon we may experience from the ground is total solar eclipses – and they are due not to the Sun – but the moon.
Solar eclipses are due to the fact that the moon covers or shadows the Sun in such a way that the entire part of the Sun disk is darkened.
Eclipses are rather rare. People often travel half the globe in order to experience the most magnificent of all eclipses – total solar eclipses.
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The development of the Sun
 When the Sun was created 4.6 billion years ago it had gone through a stage when it had been much cooler and larger than today.
On the other hand it shone up to 100 times more strongly than today.
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Modern journeys into space
 Before the space age the atmosphere obstructed many types of observations. Only visible radiation and some types of radio radiation reach the ground relatively undisturbed. Ground based observations are at the mercy of weather conditions and cannot go on when the sun is below the horizon.
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SOHO supervises the Sun
 The SOHO satellite is the largest and most complicated space observatory in history for studies of the Sun. SOHO gives us the opportunity of learning more about the interior of the Sun, the mechanisms forming and warming up the corona (the outer atmosphere of the Sun) and the reasons why the Solar wind occurs and increases.
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The solar satellite Hinode
 Hinode is a space based solar observatory launched from the Uchinoura Space Center 22nd September 2006. The Japanese Space Organisation JAXA is responsible for the building, the launching and the operation of the satellite. Before the launching it was known as Solar B. It changed its name to Hinode when it came into orbit. Hinode means "sunrise". Hinode is the follow-up of Yohkoh (Solar A) that was in operation from 1991 to 2001.
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