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Northern lights dancing again across the sky

Solar storms are expected to reach the next peak in a couple of years


Northern lights dancing again across the sky
Northern lights dancing again across the sky
Northern lights dancing again across the sky
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By Hannele Tulonen
     
      Timo Veijalainen, a nature photographer from Kittilä, has been waiting with bated breath for the sun to become active.
      And now it has happened!
     
When watching the phenomenon from earth, one can see that the polar lights - also known as the Aurora Borealis or the northern lights - are at their most visible at night, shining in the dark.
      In the evenings, Veijalainen has left his home in the neighbourhood of the illuminated Levi ski resort, driving as far as Muonio, his childhood landscape.
      As a little boy he used to lie on the snowdrifts, admiring the fires in the sky.
      The fires flaming on the night between Wednesday and Thusday were not anywhere near as magnificent as those recalled from Veijalainen’s childhood, but they were pretty damn fine, too.
      For ten years, Veijalainen has not seen northern lights that are as awesome as these were.
     
The activity of the sun can be seen on earth as sunspots on the solar photosphere, the number of which can vary over a cycle of some 11 years.
      At the end of the cycle, sunspots almost vanish into thin air.
      Now the star has again begun to pour out small particles into space, causing solar wind in the ionosphere and magnetosphere, reports Research Manager Heikki Nevanlinna from the Finnish Meteorological Institute.
      Solar wind can be created at altitudes of 80 to 100 kilometres.
     
The most recent strong solar storms occurred in 2003. The next peak is expected in 2013.
      ”Last Thursday’s solar winds were a prelude”, says Veijalainen.
     
The visibility of the Aurora Borealis is at its best during equinoxes. Then the tilt of the earth’s axis is inclined in the correct way towards the solar flare, Nevanlinna explains.
      Especially in Lapland close to the Arctic Circle, one can now be prepared for solar flares. When the number of sunspots increases, the dance of the Nordic lights becomes more and more wild and vivid.
     
The present sunspot period seems weak compared with the the ones in the past decades, Nevanlinna notes.
      There is no need to fear - at least not yet - that the solar winds would cause disturbances on earth, for example by disrupting electrical networks or appliances.
      Some people estimate that sunspots could also affect climate and weather on earth.
      Particularly during the period from 1645 to 1715, sunspots were rare, as noted by solar observers of the time.
      This period is called the Maunder Minimum.
     
The Maunder Minimum coincided with the cold period known as the Little Ice Age, during which Europe and North America were subjected to bitterly cold winters.
      The great famine of Finland (1695-1697) killed about a third of the Finnish population in the space of two years.
      Canals and rivers in Great Britain, including the River Thames, were frequently frozen during the period of cooling. "Frost Fairs" were held on the Thames, including a famous one in 1683-84.
     
Researchers are considering to what extent the sun was really contributing to the cold, as the low sunspot activity could lower the temperature of the earth only by a fraction of one degree Celcius.
      In other words, the weather in that period must have been affected by many other factors as well.
      The sun’s influence on climate change is rather small, Nevanlinna says.
     
     
For a space weather forecast see http://www.spaceweather.com/ and http://aurora.fmi.fi/public_service/
     
     
Helsingin Sanomat / First published in print 4.3.2011


Links:
  Aurora (Wikipedia)
  Sunspot (Wikipedia)
  Solar wind (Wikipedia)
  Maunder Minimum (Wikipedia)
  Great Famine of Finland (1695-1697)
  This is Finland - Aurora slideshow (great pictures)
  Sodankylä Geophysical Observatory

HANNELE TULONEN / Helsingin Sanomat
hannele.tulonen@hs.fi


  8.3.2011 - THIS WEEK
 Northern lights dancing again across the sky

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