A brief introduction to the Northern Lights

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A brief introduction to the Northern Lights

Tatiana A. Dias
September 13th, 2017
news@challenge.org

The Northern Lights are known as ‘Aurora borealis’ and ‘Aurora australis’, depending upon whether they happen in the northern or southern hemisphere. On most occasions, northern and southern auroras are mirror-like images that appear at the same time, with similar shapes and colours.
The Northern Lights are one of nature’s greatest displays. A free, multicoloured light show! But what do you actually know about this impressive phenomenon?

What are the Northern Lights?

Temperatures above the surface of the sun are in the millions of degrees Celsius, making collisions between gas molecules in the area frequent and explosive. Free electrons and protons are thrown from the sun’s atmosphere by the rotation of the sun and escape through holes in its magnetic field.

 

The Northern Lights are actually the outcome of collisions between the gaseous charged particles that the sun throws out. ‘Solar winds’ then blow them towards the earth, where its magnetic field largely deflects these charged particles. However, weaknesses at the poles allow some particles to enter our atmosphere and collide with earth’s gas particles. These collisions emit light, or what we know as the dancing lights of the north and south.

 


Colours

Auroral displays appear in many colours. These variants are due to differing types of gas particles colliding. Shades of red, yellow, green, blue, and violet have already been reported. Nonetheless, the most common auroral colour is a pale yellowish-green. Oxygen molecules situated about 60 miles above the earth produce this colours. High-altitude oxygen, at heights of up to 200 miles generates the rare, all-red auroras.  Finally, nitrogen produces blue or purplish-red auroras.

 

Forms

The lights emerge in many different forms. They can be patches of scattered light clouds, streamers, arcs, flowing curtains, or shooting rays, all light up the sky with the well-known spooky glow. The lights of the Aurora generally extend from 50 to 400 miles above the earth’s surface.

 

Where can I see the Northern Lights?

Northern Lights can be seen in an irregularly shaped oval region centred over each magnetic pole. Anyone hoping to catch a glimpse needs to head to aurora hotspots to increase their chances of viewing them. But where are these hotspots?

 

The areas where you are most likely to see the Northern Lights are at a latitude of 66 to 69 degrees north – a sliver of the world that includes northern Alaska and Canada and bits of Greenland, northern Scandinavia and northern Russia. Southern auroras are not often seen, as they are concentrated in a ring around Antarctica and the southern Indian Ocean.

 

When is the best time to see the Northern Lights?

Auroral activity is cyclic, peaking approximately every 11 years. The last peak period was 2013. Winter in the north is generally a good season to view lights. The northern lights are visible under dark skies between the months of September to April, preferably under a clear, cloudless sky. Usually seen between 5 pm and 2 am, with the prime time being at midnight on clear nights. While December to February offers the longest periods of darkness, autumn and spring are likely to offer more stable weather conditions.

 

In recent years, trying to see this elusive and ethereal vision has become a prime reason for an adventurous winter break. Share this with your friends if you could use a little help on persuading them!

 

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“ The Northern Lights are one of nature's greatest displays. A free, multicoloured light show! ”

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