In which layer of the atmosphere can we see the aurora borealis?
Correct Answer: The aurora borealis occurs in the thermosphere.
Explanation:
The aurora borealis, also known as the northern lights, is a natural light display that occurs near the polar regions. It is caused by the interaction between charged particles from the sun and the Earth’s magnetic field and atmosphere. These charged particles are mostly electrons and protons that originate from solar winds. When they reach Earth, they are guided by the planet’s magnetic field toward the polar regions.
As the particles collide with gases in the Earth’s atmosphere—primarily oxygen and nitrogen—energy is released in the form of light. This interaction occurs mainly in the thermosphere, which is the second-highest layer of the atmosphere. The thermosphere starts at around 80 kilometers (50 miles) above the Earth’s surface and extends up to 500 kilometers (310 miles) or more.
The auroras typically appear between 80 and 300 kilometers in altitude, well within the thermospheric region. This layer is ideal for such phenomena because it contains enough atmospheric particles to interact with solar wind particles, while also being far enough from the Earth’s surface to reduce atmospheric pressure that would otherwise hinder such reactions.
Different gases produce different colors. For example, collisions with oxygen can produce green or red lights, while nitrogen can give off blue or purplish hues. The specific colors seen depend on the type of gas and the altitude at which the interaction occurs.
In summary, the thermosphere provides the right conditions—sufficient altitude, available gas particles, and interaction with the magnetic field—for the beautiful light display known as the aurora borealis. This phenomenon is not only scientifically fascinating but also visually breathtaking, often drawing observers from around the world to locations near the Arctic Circle.
