Northern Lights

The Northern Lights, also called Aurora Borealis, and Norðurljós in Icelandic, are one of the most spectacular shows on this earth and can frequently be seen in Iceland from September through March on clear and crisp nights. The Northern Lights occur high above the surface of the earth where the atmosphere has become extremely thin, at an altitude of 100-250 km. They are created by electrically charged particles that make the thin air shine, not unlike a fluorescent light. Auroras can be seen in auroral belts that form 20-25 degrees around the geomagnetic poles, both the north and the south.

The name Northern Lights was first chronicled in the original Old Norse, as “norðrljós”, in 1230; while the name Aurora Borealis (“Dawn of the North”) is jointly credited to have first been used by Galileo Galilei and Petrus Gassendus in the 17th century. Derived from Aurora, the Roman goddess of Dawn, and Boreas, the Greek god of the North Wind, the name evokes some of the majestic, otherworldly splendour of an auroral display.

Solar wind and auroras
What causes this spectacular phenomenon, so characteristic of our northern skies here in Iceland? Well, it's electricity that does it - and of course it all goes back to the Sun. Simply put, the auroras are caused by the interaction of the solar wind and its embedded magnetic field with the Earth´s magnetosphere. The solar wind´s stream of highly charged particles (protons and electrons) escaping the sun, interacts with our planet’s magnetic field and atmosphere. The particles are trapped in the Earth's magnetic field and they begin to spiral back and forth along the magnetic lines of force - circle around the magnetic pole. While rushing around endlessly in their magnetic trap, some particles escape into the Earth's atmosphere. They begin to hit molecules in the atmosphere and these series of tiny collisions cause the molecules to glow, thus creating the auroras.

Colours of the Northern Lights
As all of these magnetic and electrical forces react with one another in constantly changing combinations, these shifts and flows can be seen as the auroras gracefully “dance” alongside the atmospheric currents. White and green are usually the dominant colours but sometimes there are considerable colour variations, as the pressure and composition of the atmosphere varies at different altitudes. At extremely high altitudes where the pressure is low, there tends to be a reddish glow produced by oxygen molecules when they are struck by the particles of the solar wind. At lower altitudes, where there is higher pressure, impact-irritated oxygen molecules may glow with a greenish tinge and sometimes there is a reddish lower border created by particles colliding with nitrogen molecules in the immediate vicinity.

The phenomenon is easily explained by modern science. What our ancestors may have thought when they gazed into the brightly-lit winter sky is quite another matter. At all events, don't let any scientific explanation spoil your appreciation of the beauty of the Northern Lights. They are a truly impressive spectacle, whatever their cause.

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