Key Concepts to Understand

• Temperature: The thermosphere is known for its high temperatures, but it does not feel hot because the air density is so low. This means that there are very few air molecules to transfer heat to a person or object moving through this layer of the atmosphere.
• Ionization: The high-energy solar radiation in the thermosphere causes some of the gas molecules to become ionized, meaning they lose or gain electrons and become charged particles. This ionization is responsible for the auroras (northern and southern lights) that occur near the poles.
• Low Density: Although it is very hot, the thermosphere has a very low density. The few particles that exist in this layer are mostly oxygen and nitrogen molecules, although the composition can change due to solar activity.
• International Space Station (ISS) Orbit: The ISS and other low Earth orbit satellites orbit within the thermosphere. The low density of the thermosphere means that there is very little air resistance, allowing these objects to move at high speeds with minimal drag.

Study Guide

When studying the thermosphere, it's important to understand the following key points:

1. What is the temperature range of the thermosphere and why does it not feel hot?
2. How does ionization occur in the thermosphere and what effect does it have?
3. Why is the thermosphere considered to have low density?
4. What is the significance of the thermosphere for the orbit of the International Space Station and other satellites?

Additionally, consider the following questions to deepen your understanding:

1. How does the composition of the thermosphere change during periods of high solar activity?
2. What role does the thermosphere play in the formation of auroras?
3. What are the potential challenges of working in the thermosphere for human exploration and space travel?