# What's the average temperature on the surface of ISS (International Space Station)

The ISS is about 330-410 km above earth surface and within the thermosphere layer, in which according to Wikipedia the temperature can reach 1500 °C. However the gas inside this layer is highly diluted so it feels like 0 °C, which I find very confusing (what happens to the sun light that hits the object in that layer?!). So I'm wondering how much is the average temperature on the surface of ISS.

## 1 Answer

At the altitude of ISS, the temperature depends on whether it is measured in sunlight or otherwise. In sunlight, the temperature can reach 121$^{\circ}$C, while in darkness, it can plunge to -156$^{\circ}$C. According to NASA,

Without thermal controls, the temperature of the orbiting Space Station's Sun-facing side would soar to 250 degrees F (121 C), while thermometers on the dark side would plunge to minus 250 degrees F (-157 C).