Northern Lights

The Northern Lights or aurora borealis are a natural phenomenon that can paint the night sky with unearthly, surreal color. The Southern Lights or aurora australis also occur but are not as often observed.

To observers at far-northern latitudes, the Lights are a frequent occurrence, but many who live in more temperate climates have never seen them, even though they are occasionally seen as far south as 35 degrees North latitude. This article will help you improve your chances of seeing the Lights if you journey north. The aurorae are caused by charged particles ejected from the sun. When these particles reach the earth, they collide with gas molecules in the earth's upper atmosphere, energising them and creating a spectacular multi-coloured light show. Charged particles are affected by magnetic fields, so the Lights occur mainly at far northern or southern latitudes near the Earth's magnetic poles.

The Lights look somewhat similar to a sunset in the sky at night, but appear occasionally in arcs or spirals usually following the earth's magnetic field. They fairly often look like moving curtains of light, high in the sky. They are most often light green in color but often have a hint of pink. Strong eruptions also have violet and white colors. Red northern lights are rare, but are sometimes observed.

The Lights are generally fairly dim, but sometimes bright enough that reading a newspaper on a moonless night is possible. Both brightness and how far from the poles they are visible vary according to three factors: time of year, an 11-year cycle in solar activity, and solar storms. These are discussed in more detail later.

Light pollution around cities can mask a dim aurora display. Therefore, areas at least 30 km from cities are preferred for viewing. The trick is to get far enough from cities for good viewing (generally easy, since most northern areas are not heavily populated) without taking undue risks in a climate that can easily kill you.