If the magnetic field was not present most of the particles would miss the earth and keep moving through space.įourth, an energy source that can give the plasma particles all the energy they need to create auroras is required. Third, something that can steer the plasma particles down to the atmosphere is needed. If there were no particles the situation would be the same as above. Second, there must be charged particles, plasma, that can collide with the atmosphere. If there was no atmosphere the particles from space would find no atoms to collide with and no light would be visible. The atmosphere is the screen upon which the aurora is shown. When a lot of particles collide with atoms, releasing light, an aurora occurs.įor auroras to arise on a planet five things are required.įirst of all the planet has to have an atmosphere. This occurs when the particle is approximately 100 kilometres from the Earth’s surface. When the particle has collided a number of times it has lost so much of its kinetic energy that it stops moving. Each time the particle collides it moves a bit slower and more light is emitted. As the particle moves down through the atmosphere the atoms become more and more crowded, resulting in more collisions for the particle. The next atom that collides with the particle also takes over some of its kinetic energy, resulting in the particle losing even more velocity. The atom that has taken over some energy from the particle has now got too much energy and lets go of it. The particle soon collides with a different atom. The particle keeps on moving but with less velocity, since it has lost some energy to the atom. When the particle collides with an atom, the atom takes over some of the energy that has given the particle its velocity. When a particle reaches the atmosphere it collides with one of the many present atoms. The particles are caught by the Earth’s magnetic field and are steered towards the poles. The particles that make auroras come from the ionosphere but have an extremely high velocity due to the energy from the solar wind. When the particles collide the energy used to give them their velocity changes into a light, the aurora. Auroras arise when some of those particles enter the Earth’s atmosphere and collide with atoms and molecules. The Earth is surrounded by a thin gas cover, the atmosphere, and fast charged particles, plasma, are moving in space above it. You can read a little bit about why there are auroras, how different auroras can look, some history and something about research on auroras. On the following pages you will be told about auroras. Even the Northern Saami (Lappish) word for auroras, guovsahas, is related to the light of dawn. The Latin word for southern lights is Aurora Australis, the southerly light of dawn. A translation would be the northerly light of dawn. red light of dawn, in ancient Roman mythology and Borealis means northerly. The Latin word for northern lights, Aurora Borealis, was first used in the early seventeenth century. Together the northern- and southern lights are called polar lights. A similar light is located over the southernmost parts of the world it is called southern lights. Northern lights, mostly called aurora, are the fluttering lights that can be observed in the sky over the northernmost parts of the world.
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