Radiation (Thermal)

Thermal radiation is the emission and absorption of infrared electromagnetic waves. It is the only method of thermal energy transfer that works through a vacuum.

All objects above absolute zero emit thermal radiation. Hotter objects radiate more energy per second.

Dark, matt surfaces are good emitters and absorbers. Light, shiny surfaces are poor emitters and good reflectors. This is why survival blankets are shiny, radiators are painted dark, and solar panels are black.