# How is heat energy transferred?

To explain this, we have to understand that the sun (and other stars as well) emit Electromagnetic radiation which are oscillating electric and magnetic fields propagating through space. They don't necessarily need a material medium. You might be familiar from your studies on electricity and magnetism that an electric field and a magnetic field store energy of energy densities (epsilon""_0E^2)/2 and B^2/(2mu""_0) respectively . So, you've got your answer, radiation carries energy without the need of a material medium in form of electromagnetic fields. This is how, the sun's heat reaches us.