WHAT CAUSES THE NORTHERN LIGHTS?
The
Northern Lights are actually the result of collisions between gaseous particles
in the Earth's atmosphere with charged particles released from the sun's
atmosphere. Variations in colour are due to the type of gas particles that are
colliding. The most common auroral color, a pale yellowish-green, is produced
by oxygen molecules located about 60 miles above the earth. Rare, all-red
auroras are produced by high-altitude oxygen, at heights of up to 200 miles.
Nitrogen produces blue or purplish-red aurora.
The
temperature above the surface of the sun is millions of degrees Celsius. At
this temperature, collisions between gas molecules are frequent and explosive.
Free electrons and protons are thrown from the sun's atmosphere by the rotation
of the sun and escape through holes in the magnetic field. Blown towards the
earth by the solar wind, the charged particles are largely deflected by the
earth's magnetic field. However, the earth's magnetic field is weaker at either
pole and therefore some particles enter the earth's atmosphere and collide with
gas particles. These collisions emit light that we perceive as the dancing
lights of the north (and the south).
The
lights of the Aurora generally extend from 80 kilometres (50 miles) to as high
as 640 kilometres (400 miles) above the earth's surface.
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).
WHERE IS THE BEST PLACE TO WATCH THE
NORTHERN LIGHTS?
Northern
Lights can be seen in the northern or southern hemisphere, in an irregularly
shaped oval centred over each magnetic pole. The lights are known as 'Aurora
borealis' in the north and 'Aurora australis' in the south. Scientists have
learned that in most instances northern and southern auroras are mirror-like
images that occur at the same time, with similar shapes and colors.
Because
the phenomena occurs near the magnetic poles, northern lights have been seen as
far south as New Orleans in the western hemisphere, while similar locations in
the east never experience the mysterious lights. However the best places to
watch the lights (in North America) are in the northwestern parts of Canada,
particularly the Yukon, Nunavut, Northwest Territories and Alaska. Auroral
displays can also be seen over the southern tip of Greenland and Iceland, the
northern coast of Norway and over the coastal waters north of Siberia. Southern
auroras are not often seen as they are concentrated in a ring around Antarctica
and the southern Indian Ocean.
Areas
that are not subject to 'light pollution' are the best places to watch for the
lights. Areas in the north, in smaller communities, tend to be best. 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.
LEGENDS OF THE LIGHTS
'Aurora
borealis', the lights of the northern hemisphere, means 'dawn of the north'.
'Aurora australis' means 'dawn of the south'. In Roman myths, Aurora was the
goddess of the dawn. \par Many cultural groups have legends about the lights.
In medieval times, the occurrences of auroral displays were seen as harbingers
of war or famine. The Maori of New Zealand shared a belief with many northern people
of Europe and North America that the lights were reflections from torches or
campfires.
The
Menominee Indians of Wisconsin believed that the lights indicated the location
of manabai'wok (giants) who were the spirits of great hunters and fishermen. The
Inuit of Alaska believed that the lights were the spirits of the animals they
hunted: the seals, salmon, deer and beluga whales. Other aboriginal peoples
believed that the lights were the spirits of their people.
Negative Effects of Aurora
Negative effects of the aurora are Radio communications using
HF waves across long distances may break , power outages and disrupted
communication tools.
Positive Effects of Aurora
Positive effects of the aurora are can reduce stress,
entertaining, and educating.
http://www.northernlightscentre.ca/northernlights.html
