Yukon, Northwest Territories and Northern British Columbia Travel Guide

The aurora borealis , or "Northern Lights", is a beautiful and ethereal display of light in the upper atmosphere that can be seen over large areas of northern Canada. The night sky appears to shimmer with dancing curtains of colour, ranging from luminescent monotones - most commonly green or a dark red - to fantastic veils that run the full spectrum. The display becomes more animated as it proceeds, twisting and turning in patterns called "rayed bands". As a finale, a corona sometimes appears, in which rays seem to flare in all directions from a central point.

Named after the Roman goddess of dawn, the aurora was long thought to be produced by sunlight reflected from polar snow and ice, or refracted light produced in the manner of a rainbow. Certain Inuit peoples believed the lights were the spirits of animals or ancestors; others thought they represented wicked forces. Old-time gold prospectors thought they might be vapours given off by ore deposits. Research still continues into the phenomenon, but the latest thought is that the aurora is caused by radiation emitted as light from atoms in the upper atmosphere as they are hit by fast-moving electrons and protons. The earth's geomagnetic field certainly plays some part in the creation of the aurora, but its source would appear to lie with the sun - auroras become more distinct and are seen spread over a larger area two days after intense solar activity, the time it takes the "solar wind" to arrive. This wind is composed of fast-moving electrically charged ions. When these hit the earth's atmosphere they respond to the earth's magnetic field and move towards the poles. En route they strike atoms and molecules of gas in the upper atmosphere, causing them to become temporarily charged or ionized. These molecules then release the charge, or energy, usually in the form of light. Different colours are emitted depending on the gases involved: oxygen produces a green colour (or orange at higher altitudes), nitrogen an occasionally violet colour.

You should be able to see the Northern Lights as far south as Prince George in British Columbia, over parts of northern Alberta (where on average they're visible some 160 nights a year) and over much of the Northwest Territories, Nunavut and northern Manitoba. They are at their most dazzling from December to March , when nights are longest and the sky darkest, though they are potentially visible all year round. Look out for a faint glow on the northeastern horizon after dusk, and then - if you're lucky - for the full show as the night deepens.