This image shows a quartz liner in an oven at 1150° C, and the orange glow is heat radiation. -- This radiation is much brighter than that given off by a face (see Physics in Your World) and has its maximum brightness at a much higher frequency--in the visible spectrum rather than infrared. -- For another example of a substance at 1100°-1200° C giving off heat radiation, see the San Diego State University page on basaltic lava.
