Draper point
The Draper point is the approximate temperature above which almost all solid materials visibly glow as a result of blackbody radiation. It was established at 977˚ F (525˚ C, 798 K) by John William Draper in 1847.
Bodies at temperatures just below the Draper point radiate primarily in the infrared band and at longer wavelengths, and emit negligible visible light. The value of the Draper point can be calculated using Wien's displacement law: the peak frequency ![\nu_{peak}](/Images/godic/202501/10/a37246181558264ddfd36a803e4edf023545.png")
(in hertz) emitted by a blackbody relates to temperature as follows: