News of Norway, issue 1, 2000
The northern lights have frightened people for ages - and challenged scientists for just as long. "Aurora Borealis" is the scientific name of the aurora of the northern hemisphere, which is also called the northern lights. The scientific name itself means "northern dawn".
The phenomenon is still not fully unveiled to scientists, and for ages people have believed it to be supernatural, leading to stories, myths and pictorial art to try to explain this mystery. But beyond superstition, culture, mysticism and religious beliefs lie explanations provided by research and science.
The physical phenomenon
Originating in an atmospheric layer high above the surface of the Earth, the northern lights can be seen during dark hours in the northern hemisphere.
The brightly colored light is emitted when charged particles from the sun are guided by the Earth's magnetic field into the atmosphere near the poles. When the particles contact atmospheric molecules, primarily oxygen and nitrogen, at altitudes from 60 to 180 miles, a part of the energy from the collisions transforms to visible light. The average altitude for normal intensity aurora is between 70 and 125 miles.
The forms of the lights are many, and there are categories of patterns: homogenous arc; arc with ray structure; homogenous band; band with ray structure; curtain; ray; and corona.
What causes the Aurora
· The sun emits a continuous stream of ionized gas, which includes electrons, protons and helium nuclei. This stream is called the solar wind.
· When they are closer to the Earth, the particles are influenced by the Earth's magnetic field and are guided toward oval zones around the magnetic poles.
· The solar wind particles collide with air molecules in the upper atmosphere.
· Those collisions impart energy to air molecules, primarily oxygen and nitrogen, and cause the air molecules to emit light. This emission is called the aurora. The aurora of the Arctic is often called the northern lights, while the aurora of the Antarctic is called the southern lights.
Superstitious beliefs
The Sámis believed that the northern lights had supernatural powers to resolve conflicts and they painted auroral symbols on their magic drums. Even modern Norwegian folklore says that waving pieces of white clothing at the northern lights will make the lights brighter and more spectacular.
The oldest recorded descriptions of the aurora are from the Mediterranean countries and from ancient China. Because of their temperate weather conditions, the people in those locations would have seen the aurora only once or twice in their lifetime.
In 344 BC, the Greek philosopher Aristotle observed the aurora and compared its light with flames from known sources on Earth. And in the poem 'Snow,' the Norwegian author Knut Hamsun likened the aurora with a wedding among the stars.
Flaming lights on the sky
a night of northern lights
A wedding is going on up there
among the crowd of stars
The Moon is rising
a God among sparkling Goddesses.
Aurora Andøy
Today, scientists use many instruments to study the aurora. Most measurements are made from the ground, although instruments in rocket payloads and on satellites provide data not obtainable from the ground. In the Arctic, the auroral oval crosses Siberia, Alaska and the northern part of Canada, and continues above the ocean areas south of Greenland and Iceland as well as over the populated coastal areas of northern Norway.
Andøy in Norway is uniquely located under the aurora oval on the coast of Northern Norway. This was why the Andøya Rocket Range was built in 1962, as a central facility for Norwegian and international auroral research. To go on a virtual 'northern lights safari,' visit the website www.northern-lights.no.