The Aurora Borealis is a beautiful display in the night sky. The luminous light show appears in different shapes and a combination of shades of green, blue, violet, red or yellow. Often referred to as the Northern Lights, legends used to be the only explanation for the phenomenon, with different interpretations in different cultures such as Norse and Inuit. After research from radar, observation balloons and satellites, scientists were able to explain exactly what causes it.
The particles of the sun and the upper atmosphere close to the North Pole react with one another, causing the Northern Lights to appear in the Northern Hemisphere. The equivalent happens in the Southern Hemisphere, near the South Pole, resulting in the Southern Lights (Aurora Australis). The occurrence is more likely to happen at times when there is a lot of sunspot activity or magnetic storms and is more frequent when it's equinox time. The Northern Lights are more visible, the further north it is viewed from. They are usually observed during September to October and March to April.
The lights appear between 56km-970km above the Earth's surface and sightings are usually more common through the northern regions of Norway, across Hudson Bay, through Alaska and North Siberia. It's also frequently spotted in Canada and northern United States. There are a reported 200 sightings a year in Finnish Lapland. Northern Lights and Southern Lights are not confined to Earth. The majority of planets in our Solar System have auroras too. The Hubble Telescope has sent back images of auroras at Saturn, Jupiter and Jupiter's moons. These are said to have been even more powerful than the lights observed on earth. An aurora has also been identified in the atmosphere of Mars.
The most powerful aurora ever recorded by witnesses is thought to have appeared on two occasions in 1859. These Northern Lights were said to be incredibly bright and colorful. They coincided with a turbulent magnetic storm. This was so strong as to stop telegraph lines from working properly.
Humans have looked up at the night sky with wonder since time began. The scientific theory behind the Northern Lights may not be as romantic as the myths but they do help us to explain the forces that interact above us. Children were told of the lights being caused by the shields and helmets of armies, the path of wandering animals and even the reflection of shoals of herring. Science cannot dull the effect of the free display that some of us are privileged to see.
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