Northern Lights over the Sjon Mountain. Credit: Petter Hamnes.
What were those strange quivering northern lights that both fascinated and frightened people on Earth for millennia?
For thousands of years people in the northern part of the world have marveled at the spectacular and fearful displays that occasionally light up the night sky.
There have been hundreds of stories and theories to explain these celestial lights what we now know as the aurora borealis or northern lights. But no one until about a century ago, suspected a connection with the sun.
Every northern culture has oral legends about the aurora, passed down for generations. During the viking period, northern lights were referred to as reflections from dead maidens.
The phenomenon was often referred to as a vengeful force. In ancient times, most people were afraid of the lights. Some people would not let their children outside to play while there were auroras, fearful they could get killed.
The sami (lapp) people called it guovssahas, the light you can hear. The eskimos in the northernmost parts of Canada believed that the northern lights were created by spirits, which, dressed in the mystical light, were having fun because the sun is away, that they were playing soccer with a walrus skull.
The rapidly moving auroras were called the dance of death. The Vikings who lived in Norway a thousand years ago, named it the northern lights. In Norway children were often told that by waving with white clothing, the intensity of waving increased the motion of the aurora!
The strong aurora on March 6, 1716 could be observed in large parts of Europe and gave birth to more modern science. Sir Edmund Halley published the first detailed description of the aurora in that year.
He lamented that at the age of 60 years he had given up on experiencing this amazing phenomenon. He suggested that "auroral rays are due to the particles, which are affected by the magnetic field; the rays are parallel to earth’s magnetic field."
Kristian Birkeland, painted by Åsta Nørregaard around 1900. Credit: Wikimedia.
A major breakthrough was made by an eccentric norwegian scientist – Kristian Birkeland, 1867-1917. His theory stated that charged particles from the sun could ignite auroras.
To prove his theory, which is still valid today, he built his own world in a glass box, electrified his model earth with its own magnetic field and showed how particles from the sun could ignite auroras.
The particles were captured by the earth’s magnetic field and channeled down towards the polar regions. He also showed that they would be identical and simultaneous at both poles. Birkeland, arguably Norway’s greatest scientist, also established the first permanent aurora observatory.
Birkeland indicated the existent of the solar wind and the earth’s magnetosphere and studied the properties of comet tails. Many of these ideas were not confirmed before after the space age some 60 years later.
The electrical currents he described in the upper atmosphere are still called Birkeland currents.
Two other noteworthy Norwegians in this area were Lars Vegard, the first scientist to map the colors of the aurora, and Carl Størmer, who continued where Birkeland left off and calculated that there is a belt-like area around the earth in which particles are reflected to and from between the poles.
Verification of this region came years later on the basis of satellite measurements made by the american James van Allen. Størmer also calculated the height of the northern lights to be 80-130 kilometers.
Today we know it typically extends from about 80-100 km to 250 km and on rare occasions up to 500-800 km.Thus, the aurora is not a weather phenomenon, almost all weather occurs in the first 16 km of the atmosphere.
Norway, as we have seen, has a long tradition in studying the sun and the aurora due to the fact that the sun interact with the earth system.
This field of science is often called the sunearth connection. Today, after the start of the space age, scientists are utilizing space borne instruments and cameras to study the aurora.
A sounding rocket range was established on the north Norwegian island of Andøya. It is the northernmost permanent rocket launch facility in the world and the first rocket launch there took place in 1962. More than 700 rockets have been launched, many of them NASA rockets.
By monitoring the activity on the Sun and measuring the speed of the solar wind particles one can predict the strength and the location of the aurora. By adding prediction of weather and clear sky it will provide a useful tool for aurora hunters and tourists.
Research rockets reach the northern lights from Andøya Space Center in Northern Norway. Cred: ASC
Since we are located right beneath the auroral zone there is a large number of aurora and space weather instruments currently operated in northern Norway and on the Svalbard islands in the Arctic.
This includes among others the facilities at Andøya Rocket Range, the Eiscat radars in Tromsø and at Svalbard, an extensive network of magnetometers and the aurora observatory - Kjell Henriksen Observatory (KHO) at Svalbard.
For Norway a better understanding and operational monitoring of the Sun and SpaceWeather is important for many reasons. Power grid companies need to be alerted about solas storms that can induce strong currents in the power grid and cause damage to the system.
Solar storms can degrade navgation systems such as GPS. Thus, we are monitoring the ionosphere using geodetic GPS reference stations to allow for correction for solar induced erros in the GPS signal.
Norway will be especially interested in the rapid ionospheric changes affecting navigation accuracy over the large ocean areas in the Norwegian Sea and the Barents Sea. In fact Norway has responsibility for issuing navigation accuracy warnings to seafarers in these areas.
Dynamic positioning of oil drilling ships/platforms, directional drilling, radiocommunication, and helicopter operations in the polar night have especially strong needs for space weather information.
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