Previous Year Question

Aurora Borealis, or the Northern Lights, is a luminous phenomenon observed mainly at high northern latitudes.

Energetic charged particles coming from the Sun are guided towards the polar regions by the Earth's magnetic field.

These particles collide with oxygen and nitrogen atoms and molecules in the upper atmosphere. The particles excite them, and light is emitted when they return to lower energy states.

This phenomenon occurs mainly in the ionosphere. The ionosphere is not a separate temperature-defined atmospheric layer; it is an ionized region, much of which overlaps the thermosphere.

This is why some modern descriptions also state that auroras occur in the thermosphere, but according to the options given and the conventional geographical classification, Ionosphere is the correct answer.