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Research | Space Research | Northern Lights
The Northern Lights in Finland
The Northern and Southern Lights, or Aurora Borealis and Aurora Australis, are a light phenomenon taking place in the sky in the Arctic and Antarctic regions on clear, dark nights.
The Finnish name for the lights (revontulet) comes from a Sami, or Lapp, legend whereby the tail of a fox running along snow-covered fells strikes the snow drifts, sending a trail of sparks into the sky. Revontulet literally means "foxfire".
However, researchers from further south maintain that the Northern Lights typically form at a height of 100 km as a result of charged particles (electrons and protons) accelerating in the Earth's magnetic field and colliding with air molecules. These give up part of their surplus energy in the form of light. The phenomenon is rather similar to the formation of an image in a television tube, or to the emission of light by a neon lamp. The usual greenish-yellow, and occasionally reddish, appearance of the aurora is produced by the oxygen in the atmosphere, whereas the blue and violet light is due to nitrogen. The particles causing the Northern Lights come from the sun, from which they are catapulted out into space at speeds of up to 1000 km a second on the so-called solar winds.
The study of the Northern Lights as part of the electric and magnetic phenomena taking place in space close to the Earth provides valuable information on the characteristics and behaviour of the magnetosphere.
Alongside traditional optical observation methods, equipment based on sophisticated research principles has been developed, and the FMI has also played an important role in interpreting the measurements obtained with these as part of international co-operation in this field. The Northern Lights are photographed and magnetospheric processes associated with them are observed by satellites.
Long term observations continuing from one decade to the next, together with registration of the Earth's magnetic field, provide indirect information on fluctuations in the radiative activity of the sun. Exceptional states in regard to the sun's radiation are also interesting because they have been suspected of causing disturbances in the world's climate. Long series of observations by the Finnish Meteorological Institute and its predecessors make a noteworthy contribution to this research topic.
More information:
, tel. 358 9 1929 4649
Collection of auroral figures (by Jyrki Manninen, Sodankylä Geophysical Observatory)
Suomeksi
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