Nothern Lights

The Northern Lights are one of the big three natural phenomena, created by our sun's magnetic activity. The Northern Lights are caused by large numbers of electrons that stream towards the Earth along a magnetic field and collide with air particles in our sky. The air then lights up rather like what happens in a fluorescent light tube - and what we see is the Northern Lights, also called Aurora Borealis.

The resulting colors of the Northern Lights reflect gases we find up there. The charged particles originate from the sun, and weather conditions on the sun and earth decide whether or not we will see this phenomenon (but the next pages in this section will help you optimize your chances). It's most common to see shades of green in the Northern Lights

Can I see them anywhere?
Yes. Although more frequent at higher latitudes, closer to the poles (such as in Canada, Alaska, Antarctica), they have been seen closer to the equator as far south as Mexico. To view them, look in the direction of the closest pole (the northern horizon in the northern hemisphere, the southern horizon in the southern hemisphere).

Can I see them at any time of the year?
Yes. In some areas, such as Alaska or Greenland, they may be visible most nights of the year. And they occur at any time of the day, but we can’t see them with the naked eye unless it’s dark.

What causes the colors and patterns?
Colors and patterns are from the types of ions or atoms being energized as they collide with the atmosphere and are affected by lines of magnetic force. Displays may take many forms, including rippling curtains, pulsating globs, traveling pulses, or steady glows. Altitude affects the colors. Blue violet/reds occur below 60 miles (100 km), with bright green strongest between 60-150 miles (100-240 km). Above 150 miles (240 km) ruby reds appear.

Fun Facts about northern lights:

• Auroras have been observed since ancient times.
• The height of the displays can occur up to 1000 km (620 miles), although most are between 80-120 km.
• Auroras tend to be more frequent and spectacular during high solar sunspot activity, which cycles over approximately eleven years.
• Some displays are particularly spectacular and widespread and have been highlighted in news accounts. Examples include auroral storms of August-September, 1859, Feb 11, 1958, (lights 1250 miles wide circled the Arctic from Oregon to New Hampshire) and March 13, 1989, (the whole sky turned a vivid red and the aurora was seen in Europe and North America as far south as Cuba).
• Legends abound in northern cultures to explain the northern lights. Some North American Inuit call the aurora aqsarniit(“football players”) and say the spirits of the dead are playing football with the head of a walrus. Often legends warn children that the lights might come down and snatch them away.
• June 1896, Norwegian Kristian Birkeland, the “father of modern auroral science,” suggested the theory that electrons from sunspots triggered auroras.

Sources : http://www.loc.gov/rr/scitech/mysteries/northernlights.htm                http://goscandinavia.about.com/od/knowledgesafety/ss/northern-lights.htm