The thermosphere is the layer of the Earth’s atmosphere located above the mesosphere and below the exosphere. Despite being the layer with the highest temperatures, it doesn’t feel hot to us. Here’s why:
The thermosphere absorbs a significant amount of solar radiation, particularly ultraviolet (UV) and X-ray radiation. This absorption causes the few gas molecules present in this layer to become highly energized, leading to extremely high temperatures. However, the thermosphere is also characterized by very low density. The number of gas molecules is so sparse that even though they are highly energized, there aren’t enough of them to transfer heat effectively to objects like satellites or spacecraft.
In simpler terms, while the thermosphere can reach temperatures up to 2,500°C (4,532°F) or higher during periods of high solar activity, the heat isn’t felt because the molecules are too far apart to conduct heat efficiently. This is why astronauts and satellites in the thermosphere don’t burn up despite the high temperatures.