When a body in the space receives thermal energy by radiation, this can have three possible purposes:
The energy can be absorbed by the body, increasing its thermal state.
The energy can be reflected.
The energy can be transmitted through the body.
The behaviour of the body depends on the properties of its material.

A very important concept to understand the radiation process is the view factor. Inside this factor is included information about the angles between the surface emitting the radiation and the one that receives it, the surfaces that can be seen for all the bodies taking part in the phenomena, etc... To summarise, it can be said that it contains all the geometrical parameters needed to make an appropriate evaluation of the heat transmitted by the radiation.