This page is available in Gaelic ~ link here

 

The Aurora Borealis

 

The Aurora Borealis (more commonly known as the Northern Lights) is a natural phenomenon occurring in the dark night skies of the United Kingdom more often than most people think.

It is the sky’s own gigantic light show. They are so large that they often occupy the whole of the northern night sky. These displays are caused by gas (oxygen and nitrogen) molecules being energised by the bombardment of electrically charged particles thrown into space by periodic emissions of energy from the sun.

The aurora is most easily seen at latitudes higher than 65 degrees north. In Scotland, this includes the most northerly points on the mainland as well as in Orkney and Shetland. Aurora displays are not very predictable, but their presence occurs in cycles, usually reaching a peak roughly every 11 years, and they are least likely to be seen during the summer months.

Even if only a few rays are seen, they will reach great heights in the sky. Sometimes, the huge beams of light may be colourful greens and reds of oxygen at its different heights in the atmosphere, or perhaps the violet-blues of nitrogen, pulsating in brightness and appearing to hang in a folding arc, like massive curtains in the sky. Moonlight, frost haze and different seasonal changes can affect the hues of these basic colours. 

Aurora displays can exhibit other regular forms. Theses include: 

  • Multiple arcs: occasionally a double, very rarely a triple arc 
  • Folding arcs: sometimes snake-like, sometimes like a large horseshoe 
  • Patching: fluctuating patches of light rather like small clouds flashing off and on 
  • Streaming or flaring: bases of columns flaring brightly and moving rapidly sideways 
  • Flashing: rhythmic bands of light moving upwards from the horizon like a cascading waterfall but going in the wrong direction. This usually occurs at the end of a display.

 

The surest way to see them is to look outside on a dark, clear night. Observation of the Aurora is best looked northwards and slightly to the west. The viewing site should be chosen for its freedom from close high mountains, forests or light pollution (from street lamps and house lights) from a nearby town which may obscure the view. It is a good idea to avoid roadside viewpoints too, where car headlights can dazzle you at a crucial moment – or can ruin a photograph at the time of exposure.

back