In hot countries, people paint their houses white to reduce absorption of heat energy from the Sun.

  Thermal radiation (infra red) is the transfer of heat energy by electromagnetic waves. 

  Thermal radiation travels through vacuum in straight lines at the speed of light.

                                                      Sun's heat travels through vacuum

  Objects give out (emit) and absorb thermal radiation all the time.

  No particles move in thermal radiation.

  The hotter the object the more energy it gives out (radiates).

  Dark matt surfaces are good absorbers and good emitters of thermal radiation.

  Light, shiny surfaces are poor absorbers and poor emitters of thermal radiation.