Astronauts in their bathing suits
As we have already seen, in the thermosphere the temperature increases as the distance from the Sun increases. At around 120 Km of height the temperature is 0°C, while at 300 Km it gets to 1000 °C. However we are used to seeing astronauts that have a space walk in the thermosphere wearing heated space suits in order to face unbearable temperatures. When we talk about temperature, we refer to a figure that depends on the average speed particles move at. A high temperature corresponds to a high speed of particles. Particles transmit the heat by crashing among themselves. In the thermosphere the temperature is extremely low as particles are not many and as a consequence their crashes are extremely rare. If there is no crash, there will be no heat exchange and therefore it will be cold.