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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| Definition of Plasma physics |
| The Sun-Earth space is filled with a rarefied gas consisting of freely floating electrons and positive ions – molecules and atoms which have lost one or more electrons, giving them a positive charge. Such a gas is called a plasma; it conducts electricity and tends to get attached to magnetic field lines. |
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| The Aurora |
| Auroras occur high above the Earth’s surface and can be reached only by large, expensive rockets. In order to obtain this knowledge about the production of auroras, you need to learn and understand the four subjects mentioned in the diagram below. |
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| The Earth’s Magnetic Field |
| The year 1600 represents an important milestone in the history because of the famous treatise "De Magnete" by William Gilbert. Gilbert made a magnetic model of the Earth and showed by means of a compass that the direction of the magnetic field varied with where on Earth one was located. |
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| The atmosphere and the ionosphere |
| The Earth is surrounded by a comparatively thin layer of atmosphere. And yet, the lives of all of us sensitively depend on the integrity of this layer of air. Because our atmosphere is so important, we need to have some knowledge about its composition and capacity. |
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| The Sun radiation and the solar wind |
| Physical processes on the Earth require an energy source to drive them. Not surprisingly, our main energy source is the Sun. After all, the Sun powers the food we eat, the coal and gasoline we burn; none would exist without the energy provided by sunlight. |
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| The magnetosphere |
| When the ionosphere was firmly established, scientists began to wonder about the upper extension of the ionosphere, linked magnetically to the Earth; the region we today call the magnetosphere. |
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| Radiation belts |
| Satellites provided the opportunity to begin to explore the magnetosphere. In 1958, the satellites Explorer 1 and 3 carried a particle counter that enabled professor James Van All, the PI for the project, to discover the trapped radiation belts. |
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| Adiabatic invariants – Single-particle motion |
| When fast charged particles spiral around the Earth’s magnetic field lines, while bouncing back and forth, unable to penetrate the stronger magnetism near the Earth, we say they are trapped. |
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