What are aurora australis and aurora borealis? How are these triggered?

Introduction:  Start with Definition

• • Auroras are stunning natural light displays that occur in polar regions.
    • Aurora Borealis: Also known as the Northern Lights, visible in the northern hemisphere,  primarily near the Arctic Circle. (e.g., Alaska, Norway, Canada).
    • Aurora Australis: Also known as the Southern Lights, visible in the southern hemisphere (e.g., Antarctica, parts of Australia, New Zealand).

• Can add recent examples: In Ladakh, an auroral red arc was seen in the Dark Sky Reserve in Hanle.

• Shape
  • Auroras constantly change shape and pattern due to the changing magnetic fields and flow of charged particles.

How are Auroras Triggered?

• Solar Wind Interaction: Auroras are caused by the interaction between solar winds (streams of charged particles from the sun) and the Earth’s magnetic field.
• Geomagnetic Storms: When solar winds carry highly charged particles, they disturb the Earth’s magnetosphere, leading to geomagnetic storms.
• Excitation of Atmospheric Particles:Solar wind particles collide with atoms (mostly oxygen and nitrogen) in the Earth’s upper atmosphere (ionosphere), transferring energy and exciting these atoms.
• Light Emission: As excited particles return to their normal state, they release energy in the form of visible light, creating the auroras’ characteristic colorful glow. 
  • For example, when solar wind particles collide with oxygen, a green colour light is produced. Interaction with nitrogen produces shades of blue and purple.

Conclusion:

Auroras are not just spectacular light shows but are also the result of complex space weather phenomena, revealing the dynamic interaction between Earth and solar activity.

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