From UPSC perspective, the following things are important :
Prelims level : Aurora Borealis
Mains level : Aurora and the science behind
Northern Lights, also known as aurora borealis could be visible in regions such as in the northern parts of Illinois and Pennsylvania in the US.
Try this PYQ:
What is a coma, in the context of Astronomy?
(a) Bright half of material on the comet
(b) Long tail of dust
(c) Two asteroids orbiting each other
(d) Two planets orbiting each other
- Auroras occur when charged particles ejected from the Sun’s surface — called the solar wind — enter the Earth’s atmosphere.
- While flowing toward Earth, the fast-moving solar wind carries with it the Sun’s magnetic field, which disrupts the magnetosphere — the region of space around Earth in which the magnetic field of our planet is dominant.
- When the Sun’s magnetic field approaches Earth, the protective magnetic field radiating from our planet’s poles deflects the former, thus shielding life on Earth.
- However, as this happens, the protective fields couple together to form funnels, through which charged solar wind particles are able to stream down to the poles.
- At the north and south poles, the charged particles interact with different gases in the atmosphere, causing a display of light in the sky.
- This display, known as an aurora, is seen from the Earth’s high latitude regions (called the auroral oval), and is active all year round.
Behind the name
- In the northern part of our globe, the polar lights are called aurora borealis or Northern Lights and are seen from the US (Alaska), Canada, Iceland, Greenland, Norway, Sweden and Finland.
- In the south, they are called aurora australis or southern lights and are visible from high latitudes in Antarctica, Chile, Argentina, New Zealand and Australia.
Where is it observed?
- Generally, the auroral oval is usually witnessed far up in the Polar Regions or the high latitude regions of Europe, like in Norway.
- But occasionally, the oval expands, and the lights become visible at lower latitudes.
- This happens during periods of high solar activity, such as the arrival of solar storms.
- Solar activities include solar flares, solar energetic particles, high-speed solar wind and Coronal Mass Ejections (CME).