The Mystical Lights of the World

By Sia Dhruva

Have you ever contemplated over the principle that creates one of nature’s most enthralling beauties: the Northern Lights? They are scientifically known as the Aurora Borealis and create an artist’s palette in a captivating night sky with their magnificent colourful hues. They give a glimpse of their mesmerizing and enchanting selves all year around with prominent sightings between September to April. They are usually observed closer to the Arctic Circle, including Alaska, Canada, Iceland, Greenland, Norway, Sweden and Finland. Once again, it is science that provides the basis for this intriguing phenomenon!

At any given moment, the sun is ejecting charged particles from its corona, or upper atmosphere, creating the solar wind. Energized particles from the sun slam into Earth's upper atmosphere at speeds as high as 45 million mph or 72 million Km/h. When the solar wind comes into contact with the Earth's ionosphere, or upper atmosphere, these particles are deflected towards the poles of Earth by our planet's magnetic field resulting in an interaction with our atmosphere. This deposits energy and causes the atmosphere to fluoresce giving birth to an aurora.

It is the chemical composition of the gases in the Earth’s atmosphere and the altitude at which the auroras form that creates such a glorifying multitude of hues. The ions and atoms are deflected by the magnetic field with varying strengths which causes a glamorous and vibrant show. Blue violet and reds occur below 60 miles (100 km), with bright green strongest between 60-150 miles (100-240 km). Above 150 miles (240 km) ruby reds appear. Moreover, every type of atom or molecule emits its own set of colours. Nitrogen molecules contribute by producing glittering red and oxygen molecules give out a shimmering green.

However, not all is red and green. There is a mystery that surrounds the aurora borealis: scientists had long wondered how the energized particles in the solar wind accelerated to the extraordinary speeds of 45 million mph. It was not until June 2021, that the mystery was partly resolved. Alfen waves - low-frequency yet powerful undulations that occur in plasma due to electromagnetic force – give the particles a boost. The electrons that construct the Northern Lights move around the Alfvén waves thus accelerating rapidly.

NASA is currently investigating the true cause behind the occurrence of the northern lights through the Parker solar probe. The probe marked a remarkable feat in history reaching a new milestone on the wall of revolutionary science when it became the very first to touch the sun’s corona on December 15, 2021. It sampled particles and magnetic fields from the sun’s corona which NASA claims to use to decode the facts about the powerful solar wind. Hence, the key to this exemplary wonder will soon be revealed after thorough examination and experimentation.

Coming back to Earth and the changing course of mother nature around us, a question surely remains - Will the diabolical climate change around the world diminish the splendour of the Northern Lights? Well, technically no. Climate change caused by greenhouse gas emissions does not serve to decline the existing levels of nitrogen and oxygen in our atmosphere as per research conducted. Therefore, since the principal gases forming the aurora borealis are not disrupted, the question of the disappearance of the Northern Lights due to severe climate change dissolves in thin air. Pollution and excessive cloud formation, although, can reduce the number of northern light sightings per year, decreasing the chances that you might spot one!

They surely are a majestic sight and the science behind them is even more fascinating and sensational. We can truly say the universe has used beautiful science to create the world.

Sources:

https://www.loc.gov/everyday-mysteries/item/what-are-the-northern-lights/

https://grapevine.is/mag/articles/2019/05/10/ask-a-physical-chemist-will-long-term-climate-change-affect-the-northern-lights/

https://www.space.com/15139-northern-lights-auroras-earth-facts-sdcmp.html

https://www.livescience.com/48463-facts-about-northern-lights.html