Northern Lights: Did You Know?

Illuminating facts, stats and trivia about the majestic Northern Lights.

Divine and weathered name

The scientific name for Northern Lights is ‘Aurora Borealis’. ‘Aurora’ after the goddess of dawn, whom according to ancient Roman mythology renewed herself every morning to fly across the sky to announce the arrival of the sun. ‘Borealis’ after the Greek name for ‘north wind’. While French scientist Pierre Gassendi is regularly credited for coining and using the term to describe the illuminating phenomena in 1621, Italian guru Galileo Galilei is most commonly cited as parenting the term in 1616.

Colourful myths

From fiery foxes and spiritual football to ghostly dancing – Northern Lights have sparked some rather dramatic myths throughout the ages. On Finnish shores, they are commonly referred to as ‘revontulet’, which translates as ‘fox fires’. Legend has it that Lapland was once populated with foxes made of fire, and ancient Finnish folk believed Northern Lights to be sparks shot into the sky from the flaming creatures tails. And according to Inuit folklore, Northern Lights are the spirits of the dead playing football with a walrus skull in the night sky, while Algonquin Indians rather poetically recognised them as their ancestors dancing around a ceremonial fire.

In a nutshell

In layman terms, Northern Lights are generated by high-energy ion particles (commonly called solar winds) that are emitted from the sun. As they speed along towards Earth, they collide with air particles and gases along the planet’s magnetic field. This reaction illuminates the sky with a spectacular sculpted array of colour akin to a laser show.

Faster than the speed of light

Ions leave the surface of the sun and travel at speeds between 0.04 and 0.4 AU per hour. An AU is equal to approximately 150,000,000 km, but even at such staggering acceleration, they can take between 3 and 30 hours to display themselves as Northern Lights.

Colour clarification

Sunlight contains all the colours of the rainbow in an unbroken series from blue through green and yellow to red. In an aurora, on the other hand, the light is collected in a selection of narrow bands of colour called spectral lines. When the solar wind collides with the Earth’s atmosphere, the molecules and atoms in the gas become infused with energy, emitting shafts of light. The lights are characteristically a greenish-yellow colour (due to the oxygen) with an element of blue (from nitrogen). Sometimes the lights acquire an element of reddish-violet on the lower border, which is the influence of a positive ion of nitrogen gas. When red can be seen in the upper parts, it is the higher altitude oxygen at play.

Global power

Northern Lights belong primarily to the polar regions of the world, occurring most often in a belt around the magnetic pole at a distance of 2,500 km from it. However, they have been sighted in some pretty far-flung places around the globe throughout history. They are recorded as being visible in Bombay and Egypt in February 1872, and Singapore and Jakarta in September 1909.

High lights

Distinguishing the above-ground-level height of Northern Lights perplexed the world up until 1910, at which point scientists began photographing them from different points simultaneously and using triangular mathematical formula to decipher their dimensions. The most common height of Northern Lights is considered to be between 90 km and 130 km above ground level, although some auroras have been known to extend to heights of several hundred km. By way of comparison, a jet normally flies at a height of around 10 km, and the ozone layer is located 20-30km up.

The sound of silence

Although it is yet to be scientifically proven, many have reported hearing distinctive crackling sounds from intense displays of Northern Lights on still nights. The notion that sound could be audible to the human ear from heights of 100 km is in fact pretty inconceivable, regardless of the fact that the powerful electrical field connected with Northern Lights – capable of interfering with radio, television and satellite communications – can be recorded at ground level.

Lavish lights on the horizon

Scientists predict that the 2012 Solar Maximum – a period when the sun’s magnetic field on the solar equator rotates at a slightly faster pace than at the solar poles – will make the display of Northern Lights more spectacular than when many Mexicans were stunned by three auroras in 1958. If it is as dramatic as NASA projects, they could cause disruption to telecommunication networks, GPS and even the national grid.