WHAT ARE THE NORTHERN LIGHTS? The amazing display of lights known as the Northern Lights is caused when a set of energetic charged particles collide with atoms in a layer of the atmosphere known as the 'thermosphere'. For a more in detail description i went to a site and found this:
The origin of the aurora begins on the surface of the sun when solar activity ejects a cloud of gas. Scientists call this a coronal mass ejection (CME). If one of these reaches earth, taking about 2 to 3 days, it collides with the Earth’s magnetic field. This field is invisible, and if you could see its shape, it would make Earth look like a comet with a long magnetic ‘tail’ stretching a million miles behind Earth in the opposite direction of the sun.
When a coronal mass ejection collides with the magnetic field, it causes complex changes to happen to the magnetic tail region. These changes generate currents of charged particles, which then flow along lines of magnetic force into the Polar Regions. These particles are boosted in energy in Earth’s upper atmosphere, and when they collide with oxygen and nitrogen atoms, they produce dazzling auroral light.
LINK TO THIS SIGHT

WHEN IS IT BEST TO SEE THE LIGHTS? The best times to see the lights is December to March when nights are longest and the sky darkest at about 6 p.m. to 1a.m. This light display lasts aproximatly 10-15 minutes s the lights twist and turn in the sky. And although they are their present, we cannot see the Northern Lights unless it is dark.

WHERE IS THE BEST PLACE TO SEE THE LIGHTS:  The Northern Lights can be seen throughout: northern Scandinavia, Iceland and the southern tip of Greenland, over northern Canada (Northwest Territories, Manitoba and the Yukon), Alaska and along the northern coast of Siberia. To beLake Laberge, Yukon Territory, Canada more specific, the very best destinations are:
- Abisko, Northern Sweden
- Tromsø, Northern Norway
- Lake Laberge, Yukon Territory, Canada
- Saariselkä, Lapland, Finland