What is the highest layer of the atmosphere?

The highest layer of the atmosphere is indeed the thermosphere. This layer extends from about 85 kilometers (53 miles) above the Earth's surface to the outer edge of space, which can reach up to 600 kilometers (373 miles) or more, depending on solar activity. The thermosphere is characterized by a significant increase in temperature with altitude, which can reach up to 2,500 degrees Celsius (4,500 degrees Fahrenheit) or higher. However, despite this high temperature, the thermosphere would not feel hot to a human because the extremely thin air contains very few molecules to transfer heat.

The thermosphere plays a crucial role in various atmospheric phenomena, such as the auroras (Northern and Southern Lights) and is where the International Space Station orbits. This layer also contains the ionosphere, a region vital for radio communications.

Understanding the structure of the atmosphere is important in aviation, as different layers have varying impacts on aircraft performance, weather patterns, and flight planning.