A black-body at room temperature appears black, as most of the energy it radiates is infra-red and cannot be perceived by the human eye. Because the human eye cannot perceive color at very low light intensities, a black body, viewed in the dark at the lowest just faintly visible temperature, subjectively appears grey, even though its objective physical spectrum peaks in the infrared range.[5] When it becomes a little hotter, it appears dull red. As its temperature increases further it eventually becomes blindingly brilliant blue-white.
Black-body radiation is the type of electromagnetic radiation within or surrounding a body in thermodynamic equilibrium