without turning red. Metal light emission depends almost entirely on blackbody radiation [0] which depends only on temperature. Aluminum melts at lower tempera

without turning red. Metal light emission depends almost entirely on blackbody radiation [0] which depends only on temperature. Aluminum melts at lower temperatures than iron and that's why iron glows before it melts and aluminum doesn't. Blackbody radiation is also the principal source of sunlight (and all starlight). It was one of the first physical phenomena that required the quantum theory of energy to explain. [0] http://en.wikipedia.org/wiki/Black-body_radiation http://en.wikipedia.org/wiki/Black-body_radiation