Great Institute of Physics video on what causes the Northern Lights
Quick summary on what causes the northern lights
What causes the northern lightsThe Northern lights happen after collisions between charged particles released from the sun and gaseous particles in the Earth´s atmosphere. The color variations are due to what type of particles are colliding. Most often it is yellowish green produced by oxygen molecules located around 55 miles above earth. However we can sometimes see redish lights that are produced by high-altitude oxygen, at the heights of up to 150 miles. We also have nitrogen that produces blue or purple-red northern lights.
Since 1880 scientists have been suspecting the connection between the northern lights and the solar activity. In 1950 a research was conducted showing how the electrons and protons from solar activities are blown towards the earth in something called “solar wind”. The surface of the sun is millions of degrees on Celsius. At this temperature, gas molecules collide frequently and explode. By the rotation of the sun these free electrons and protons are thrown from the sun towards the earth by the solar wind. Then they are largely deflected when they hit the earth´s magnetic field.
The earth´s magnetic field is weaker at either the southern or northern pole and hence the particles enter the earth´s atmosphere and collide with the particles at the north or south poles. These collisions emit the dancing lights we know as Aurora Borealis or Northern Lights. Most often the dancing happens at the height of 50-60 miles, but can go as high as 400-450 miles above the earth´s surface.
The best time to see the northern lights are normally in the winter time. The long periods of darkness and often the clear nights provide us with many opportunities to watching the northern lights dancing in the sky. Research has also shown that auroral activity is cyclic, and peaking every 11 years. Next peak is going to be around 2013. Hope this has helped you understand better what causes the northern lights and it will be a good start for your Iceland holidays.
Northern Lights from Christian Mülhauser on Vimeo.
