The Van Allen Radiation Belt does not have a temperature in the traditional sense, as it is not a solid object or a gas with particles that can be measured for temperature. Instead, it is a region of space filled with high-energy charged particles, primarily electrons and protons, trapped by Earth’s magnetic field.
These particles move at extremely high speeds, but because they are so sparse, they do not collide frequently enough to establish a thermal equilibrium, which is necessary to define a temperature. Therefore, it is more accurate to describe the Van Allen Radiation Belt in terms of the energy levels of the particles rather than a specific temperature.
In summary, while we can measure the energy of the particles within the Van Allen Radiation Belt, assigning a temperature to this region is not scientifically meaningful.