Physics of space plasma
During the space age, the principles on which the physics of space plasma are based have expanded tremendously. With the development of advanced techniques, new parameters and physical processes became amenable to scientific study. Concurrently, space physics also called plasma physics has been established as a separate discipline of physics. The auroral science has thus evolved toward the point of view that is encompassed by the term space plasma physics. |
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| A brief history of solar-terrestrial physics |
 The magnetized plasma of solar origin interacts with the Earth’s magnetic field and its upper atmosphere. These interactions are often complex, because the spatial and temporal varying electromagnetic fields, that determine the motions of the charged particles. |
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| The Sun´s radiations |
 The Sun is our nearest star – a star like all other stars, and the source of energy for life on Earth. It is an enormous gas sphere nearly 4,5 billion years old. It is about 150 million km away (93 million miles), a distance which sunlight covers in approximately 8 minutes, whereas the distance to the Moon is only 1.3 light-seconds. This distance between Sun and Earth is also called 1 AU – one astronomic unit. |
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| The Earth’s Magnetic Field and the Magnetosphere |
 The Earth as a whole acts as a magnet. The field is not only attached to the Earth, but it extends far outside the atmosphere. Its direction at any point in space is the direction found by the vector sum of its horizontal and vertical components. |
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| The Atmosphere and the Ionosphere |
 The atmosphere above ~10 km, i.e. the atmosphere above the "weather zone" - the troposphere, is the main topic of discussion. The middle atmosphere ranges between 10-90 km and includes the stratosphere and the mesosphere. The upper atmosphere starts at 90 km and includes the ionosphere |
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| Northern Lights – the light organ of the polar sky |
 Auroras – often called northern lights are nature’s most magnificent display. These fantastic, glorious lights appeal to our imagination. During large displays the aurora changes constantly. It dances back and forth over the sky, in many different forms and combinations of sparkling colours. |
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