The Science Behind the Magic on Northern Lights Trips

The aurora borealis has always fascinated mankind; as a result of this deep held interest, people from all over the world undertake Northern Lights trips in order to see the brilliant light show lighting up the earth's atmosphere. But just what is it they are seeing?

Understanding the aurora borealis

The auroras surrounding the north magnetic pole (aurora borealis) occur when highly charged electrons from the solar wind interact with elements in the earth's atmosphere. Solar winds stream away from the sun at speeds of about 1 million miles per hour; when they reach the earth, some 40 hours after leaving the sun, they follow the lines of magnetic force generated by the earth's core and subsequently flow through the magnetosphere. (This is a teardrop-shaped area of the earth’s atmosphere, which is highly charged with electrical and magnetic fields.)

What are the colours?

As the electrons enter the area of the planet’s atmosphere, they will encounter atoms of oxygen and nitrogen at altitudes ranging anywhere from 20 to 200 miles above the earth's surface. The colour of the auroras seen on Northern Lights trips depends on which atom is struck, as well as the altitude of the atomic collision. Green light shows mean that oxygen is colliding with electronic particles at altitudes up to 150 miles, whereas red hues are given off when oxygen interacts with electrons above 150 miles in elevation. Blue light shows mean that nitrogen is colliding with electronic particles at altitudes up to 60 miles, whereas purple hues are given off when nitrogen interacts with electrons above 60 miles in elevation.

Understanding the "dance"

All the magnetic and electrical forces react with one another in constantly shifting combinations. These shifts and flows can be seen as the lights "dance," moving along with the atmospheric currents that can reach 20,000,000 amperes at 50,000 volts. To put this electric charge in context, the average circuit breakers in a home will disengage and short-circuit when the current flow exceeds 15-30 amperes at 120 volts. Thus, those on Northern Lights trips truly are observing the earth’s most powerful naturally occurring phenomenon.

Where and when?

The auroras generally occur along the "auroral ovals", which centre on the magnetic poles (not the geographic poles) and roughly correspond with the Arctic and Antarctic circles. There are times, though, when the lights are further south, usually when there are a lot of sunspots. Sunspot activity follows an 11-year cycle, and we are currently in a period known as the ‘solar maximum’, or ‘solar max’. The solar max is the duration within the sun’s 11-year solar cycle when it exhibits the most sunspots, and thus the most electronically charged activity. For this reason, aurora sightings are most frequent during the solar max. NASA has reported that the solar max is going to last through the winter season of 2014 into early 2015, so if you’re contemplating any one of the destinations for Northern Lights trips, now is an excellent time.

Abigail Collins is director of Aurora Nights, a company offering a select range of once in a lifetime holidays to see the Northern Lights. For the best Northern Lights trips Iceland and Swedish Lapland offer an excellent chance to encounter the aurora borealis. Aurora Nights is part of Weekend a la Carte, a family-run company with vast in-depth knowledge based on their extensive travels to the region of the Aurora Borealis and passionate about giving superb client service.