The basic goal of this experiment is the determination of the solar surface temperature from the relative intensities of the spectrum sampled at a number of wavelengths from 450 to 880 nm. The sampling is determined by a set of broadband interference filters that modulate the light intensity measured by the photocurrent in a reverse biased silicon diode. If the detailed characteristics of the filters and photodiode were all initially well known, a single set of measurements of sunlight through the filter set would suffice. In the absence of such information, the light from a tungsten lamp at different temperatures will be used to establish the appropriate calibrations. In addition, sunlight is also reddened by the atmosphere, which differentially absorbs the blue end of the spectrum. This effect can be corrected by measuring the spectral intensities as a function of zenith angle. Finally, least squares techniques determine the solar temperature by modeling the data with the Planck spectral distribution function. The experimental setup was developed by Professor Carl Akerlof at The University of Michigan.

The experiment was performed during the Blackbody Radiation and the Solar Surface Temperature workshop at the 2009 Topical Conference on Advanced Laboratories.