A nonstandard method for determining solar temperature has been presented. This method is based on the comparison between the brightness of a commercially available incandescent lamp and the Sun. This comparison is quantitative, due to the well‐known properties of tungsten. Planck’s law too has a fundamental role in this comparison. A silicon cell with an interference filter which has a central wavelength of 600 nm is used to examine the two sources of light. A quite satisfactory value of the solar temperature—about 5700 K—has been obtained in this way, and some interesting points are raised in connection with the radiation constantc2of Planck’s law. The experiment may be considered as an advanced project concerning solar energy teaching or blackbody radiation theory.