Context - On Friday night, people from across the world were treated to a rare spectacle: vivid aurorae hanging like curtains of light in the sky. They appeared even in places where aurorae aren’t usually visible. For instance, people at the Indian Astronomical Observatory spotted an aurora over Hanle in Ladakh — far away from places near the poles.
What are Auroras?
- Auroras are a natural light display in the sky, predominantly seen in the high-latitude regions (around the Arctic and Antarctic).
- It is called aurora borealis or northern lights near the North Pole.
- It is called aurora australis or southern lights near the South Pole.
What causes it?
- Interaction of charged particles from the sun with the Earth’s atmosphere.
- Apart from heat and light, the Sun also releases energetic charged particles. The protective magnetic field around Earth shields us from most of the energy and particles.
- However, the Sun does not send the same amount of energy all the time. There is a constant streaming solar wind and there are also solar storms.
- During one kind of solar storm called a coronal mass ejection, the Sun ejects a huge bubble of electrified gas that can travel through space at high speeds.
- When a solar storm comes toward Earth, some of the energy and small particles can travel down the magnetic field lines at the north and south poles and enter into the Earth’s atmosphere.
- There, the particles interact with gases in Earth’s atmosphere and result in beautiful displays of light in the sky.
- Oxygen gives off green and red light.
- Nitrogen glows blue and purple.
Why are Auroras found only at the Poles?
- The reason that the Aurora can only be seen at the poles has to do with how the Earth's magnetic field acts.
- The Earth has a metal core and acts much like a bar magnet with two poles and a magnetic field.
- Charged particles from the Sun get sucked into the Earth's magnetic field and are then channelled toward the poles, where they are channelled toward a ring around each pole.
- The charged particles are trapped in the loops of the magnetic field and are then carried toward the poles.
