Technical Visits: IRF, Northern lights

Northern Lights

Ever since IRF was founded as the Kiruna Geophysical Observatory in 1957, it has specialized in studying the northern lights. The northern lights, Aurora Borealis, often appear in the sky as long, curling yellowish-green bands that move and change shape with surprising speed.

Auroras are the result of the interplay between the sun and the earth’s magnetic field.

The spectacular show begins when charged particles are hurled from the sun as the solar wind. A portion of these particles are captured by the earth’s magnetic field and when they reach the atmosphere they are traveling at very high speeds. The light phenomena are a result of these charged particles colliding with atoms and molecules present in the atmosphere, where a portion of the particles’ kinetic energy is transformed into light, the northern lights.

The color of the northern lights is usually yellow-green, but can also be red or violet. The different colors depend on which type of atoms (mostly oxygen and nitrogen) that are hit by the charged particles, which velocity they have and type of charge. The most intense northern lights lie at an altitude of about 100 km, themselves encompassing a height of 10-30 km, but can stretch several hundreds of kilometers up, 1000 km at the most.

When and where is the best chance of seeing the northern lights? First of all, it has to be dark in order for the northern lights to be visible, and your chances are greater if you venture out to an open spot without any artificial lighting. It is only during the winter-half of the year, between September and April, that the nights are dark enough to see them clearly. You have the greatest chance of seeing the northern lights where they appear most frequently, which is up in Sweden’s Norrbotten County.

LECTURERS on NORTHERN LIGHTS: Lars Eliasson, Rick McGregor
TIME REQUIRED: Approximately half a day or 2-2½ hours.
AVAILABILITY: Year-round, upon request.