Auroras, also known as the polar lights, result from solar flares passing
through the north and south magnetic poles of the Earth.
When these solar winds that carry charged particles collide with the
electrons of the earth's atmosphere, it forms different colors and
surrealistic shapes. Green Northern lights are more common and red lights
usually occur at higher altitudes (150 miles above the ground).
Auroras paced with an 11-year cycle of the sunspot activities. The sunspot
activities were relatively muted in 2006-2007, and thus 2013 is the best
year to see the polar lights. However, it doesn't mean that anytime in the
whole year is good. The best months are March and October, which are
extremely cold.
Auroras appear in a circular band centering on the north and south
magnetic poles. Needless to say, auroras are called the Northern lights
near the North Pole and Southern lights near the South Poles. However, the
former is more accessible than the later, unless you are a scientist
stationed in Antarctica. On the contrary, many cities and towns fall into
the circular band of the Northern lights, such as several cities in North
Europe, Fairbanks (US), Dawson City, Whitehorse, Yellowknife (Canada).
I went to Whitehorse in late March, and the preceding photos were taken on
March 27, 2013, which was a full-moon night. This was not the ideal time
because the Aurora appeared weaker under the full moon. I didn't complain!
Some people took three trips but never seen any Aurora.