Aurora Excursion, Tromsø, Norway

Gallery Solar winds Camera settings


Solar winds
It all starts on the sun. The sun sends out a continous stream of positively charged particles from sun spots that explodes. These particles are sent into space in all directions, some of it is destined for earth and is named solar wind.

Northern Lights
When the solar winds strikes the magnetic field on the illuminated side of earth it gets deflected around the earth to the dark side of earth and then towards the poles along the lines of the magnetic field. The solar winds arrive over the poles with a speed of over 1 million kilometers per hour (over half a million mph). The particles collides with molecules in the upper atmosphere and creates a fantastic light in different colors. This is the phenomenon that we call the northern lights and southern lights in Antarctica.

The northern lights never appears in altitudes lower than 80 kilometers and seldomly higher than 500 kilometers. Nothern lights with maximum intensity is often found in heights of 110-200 kilometers above the earths surface. The colors depends on the altitude, blue and violet lights are mostly in altitudes lower than 120 kilometers. Most often, the northern lights will be green, which means it operates in altitudes of 120-180 kilometers. Above this, we see the red and yellow northern lights.

Aurora Borealis is the international name for the northern lights.

The Northern Lights Oval

The center of the the northern lights oval in the northern hemisphere is at 65 degrees north and is around 10 degrees wide, but will expand with high northern lights activity. Tromsø is in the middle of the oval. The northern lights oval extends through huge areas, but a lot of these areas are sparsely populated or unpopulated and not accessible for most people.

With high northern lights activity and strong solar winds the northern lights oval expands and the lights will be visible further south. With strong solar winds the northern lights can be visible over the central and southern Europe and also parts of the USA.

Geomagnetical solar storms (solar winds) are measured by a KP-index from 0 to 9.

KP-index numbers of 0 to 3 is little activity, numbers of 5 and higher are classified as solar storms. In Tromsø, we can see the lights even if the KP-index shows 0.


Fantastic Aurora: Inside the Sun to Earth's Poles




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