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Aurora [Blog]

Updated: Aug 4

Author: Afreen Hossain



A mesmerizing spectacle of ethereal luminescence known as aurora, also referred to as the polar lights, Northern lights or Southern lights, graces the heavens above Earth. This awe-inspiring phenomenon predominantly blesses high-latitude regions near the Arctic and Antarctic where its splendor unfolds, enchanting the onlooker, the celestial canopy becomes a canvas for an ever-changing dance of vibrant radiance presenting an array of unique and spellbinding patterns reminiscent of cascading drapes, celestial beams, intricate spirals and mesmerizingly dynamic flickers.


Alaska has reported seeing auroras. Auroras are also visible from orbit. These are referred to as Aurora Borealis or Northern lights in the northern hemisphere. It is also referred to as the Southern lights or Aurora Australis in the southern hemisphere. Auroras can even be found on other planets besides Earth. A planet will have auroras if it has an atmosphere and magnetic field. So, an aurora appears as a stunning show of lights in the night sky. But what creates this stunning light show? These are brought on by the Sun! Yes! Along with the ongoing flow of heat and light, the Sun also constantly transfers electrons and other types of energy to the planet. The term for this is solar wind. The magnetic field surrounding Earth holds certain charged particles in the space surrounding us while also shielding us from the majority of solar winds. The solar winds that the planet produces are not constant. There are occasions when the energy's intensity spikes, sending a cascade of charged particles hurtling toward our globe. Solar storms are the name given to these events nowadays. The Sun releases massive gas bubbles known as Coronal Mass Ejections that rupture, sending energized particles hurtling into the void of space. These particles engage in an enthralling interplay with our magnetic field as they get to Earth, preparing the scene for a celestial show. Some of these particles make a beautiful descent into the magnetic poles, both the North and South ones, where they engage in a charming collision with air particles. The captivating result of these meetings is a stunning exhibition in which a wide range of colors gently embellish the night sky - auroras. Green and red lights are formed as a result of the collision of the particles with Oxygen gas molecules in the environment. And the process produces blue and purple light when the particles collide with atmospheric Nitrogen gas molecules.


Now, you must be wondering why do the energy particles, that are emitted by solar wind and solar storms, go only towards the poles of the Earth? Our planet's magnetic field resembles a conventional bar magnet and exhibits magnetic lines of force that go from the magnetic North pole to the magnetic South pole. But the Earth's magnetic field goes beyond straightforwardness, revealing a complex structure like a dipole arrangement. In close proximity to the magnetic poles, magnetic field lines gracefully bend and converge, adding to the intricacy. When charged particles like electrons and protons approach Earth, magnetic fields have an impact on them, due to Lorentz force. The particles are forced to travel along a curved path by this force, which operates perpendicular to both the magnetic field and the particle's velocity. The magnetic lines of force of the Earth's magnetic field operate as alluring "funnels" for the charged particles as they gradually converge close to the magnetic poles. As a result, the charged particles gracefully travel along the magnetic field lines as they are directed towards the direction of the polar regions. Until they reach the highest layers of the atmosphere close to the poles, these particles obediently follow the pathways indicated by the field lines. The mesmerizing and bright auroras that adorn our sky are caused by their fascinating encounters with gas molecules there.


References

Aurora Borealis Explained. https://youtu.be/1DXHE4kt3Fw

What is an Aurora? https://youtu.be/PgIKsuZ3RZU

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