Auroras – UPSC Prelims

Auroras are a mysterious and unpredictable display of light in the night sky.

Auroras are caused when charged particles ejected from the Sun’s surface, called the solar wind, enter the Earth’s atmosphere. These particles are harmful, and our planet is protected by the geomagnetic field, which preserves life by shielding us from the solar wind.

However, at the north and south poles, some of these solar wind particles are able to continuously stream down and interact with different gases in the atmosphere to cause a display of light in the night sky.

This display of Light is known as aurora. They are seen from the Earth’s high latitude regions (called the auroral oval) and are active all year round.

In the northern part of our globe, these lights are called aurora borealis or Northern Lights. In the south, they are called aurora australis or southern lights.

Auroras are not just something that happens on Earth. If a planet has an atmosphere and magnetic field, they probably have auroras.

Unlike auroras on Earth, which are seen only near the north and south poles, Discrete Auroras (DA) on Mars are seen all around the planet at night time.

Unlike Earth, which has a strong magnetic field, the Mars magnetic field has largely died out. This is because the molten iron at the interior of the planet – which produces magnetism – has cooled.

However, the Martian crust, which hardened billions of years ago when the magnetic field still existed, retains some magnetism.

So, in contrast with Earth, which acts like one single bar magnet, magnetism on Mars is unevenly distributed, with fields strewn across the planet and differing in direction and strength.

These disjointed fields channel the solar wind to different parts of the Martian atmosphere, creating “discrete” auroras over the entire surface of the planet as charged particles interact with atoms and molecules in the sky– as they do on Earth.