How the sky is turned into a canvas by the Northern Lights ?

"I want to go to Wayanad again. The Milky Way is clearly visible in the pollution free, bright, starry night in this Kerala district during summers", said Rajarshi. We were brainstorming on the weekend getaways near Bengaluru and Rajarshi (or Raj, as we call him) came up with a unique reasoning to visit the hilly area. "I know why you want to go to Wayanad again. You betrayer", Abhirup remarked scornfully.

"Bro, you have already seen our galaxy many times. See something new now. Plan for a trip to Finland for Northern lights. Right now, we aren't visiting Wayanad again", I replied. "The northern lights are definitely in my bucket list, but right now, Milky Way is my immediate goal. I will be going, with or without you guys", frowned Raj.

Well this blog is about Northern lights. Milk Way will see the light of the day sometime later, probably.😉

Northern Lights or Aurora Borealis

"Beauty lies in the eyes of the beholder". True, but I really feel that a few things are so innately beautiful that it will be really difficult to find someone with an altering view. Coral reefs for example. The probability of people not liking the marine wonder is very minute. Similar is the case with "Aurora Borealis" or the 'Northern Lights'. One cannot claim to have not been fascinated by these naturally occurring, non-earth like, mystical, divine lights. Like an artist's gentle stroke on a white cloth canvas with a multi-coloured brush, the lights paint up the canvas made out of sky. But how are these formed? Read on to know ..

How are Northern lights formed?

Sun is a vast source of energy, a raging ball of fire. Through a process called 'Coronal Mass Ejection', the Sun belches out electronically charged particles into the space. These particles, also called Solar winds, move away from the Sun into the expansive universe. When the Solar wind finds Earth on the way, it reacts with the earth's magnetic field, which deflects most of the particles. However, a few of the particles find their way into the earth's atmosphere via the magnetic poles.

Credit:NASA/Steele Hill

At earth, the solar wind interacts with atoms and molecules present in the atmosphere, which leads to the increase in the energy level of the electrons i.e. electrons move up to the excited state. After some time, the energy wanes, forcing the electrons to leave the excited state for the original energy level. In the process, they give out photons which cause light to be generated. 

The process at a mass scale results in Auroras.

What about the different colours in the Aurora?

The different colours are due to the mixing of solar particles with the molecules of the Earth's atmosphere. The interaction of solar particles with Oxygen molecules results in the generation of Green colour. Nitrogen on the other hand leads to formation of pink and blue colour.

• Oxygen + Solar particles = Green
• Nitrogen + Solar particles = Pink / Blue

What are the best places to view Auroras and when?

Auroras can be best witnessed in the northern as well as southern hemisphere, near the earth's magnetic poles. Geographically, they lie between 60°-75° latitudes. The Northern Auroras are called Aurora Borealis while Southern lights are called Aurora Australis. The countries where one can witness these awe-inspiring natural phenomenon are Norway, Sweden, Finland, Canada, Iceland and Greenland (Why Greenland and Iceland have opposite names? Read here). The optimum time is midnight, 12 am - 2 am. 

At times, during high incursion of solar wind in atmosphere, these lights can be seen even in the lower latitudes.

Nerd Notes:

1. In Norse mythology, the aurora is considered to be a fire bridge to the sky built by the Gods
2. Auroras allegedly peak every 11 years i.e. once in a Solar cycle 

Keep reading and don't forget to smile 😃
-Prakhar