Using a spectroradiometer, scientists were able to measure the radiative temperature and thermal output from the Kupaianaha Lava Lake. This instrument collects spectra from 0.4–3.0 micrometers in over 800 channels, thereby permitting an accurate determination of the blackbody temperature of the surface. Such studies are of value because they show that the surface of a lava lake (or a lava flow) is remarkably cool — perhaps only a few hundred degrees centigrade — compared to the eruptive temperature of approximately 1150°C. Such temperatures are quite similar to those the Voyager 1 spacecraft measured for the volcanic activity on Io (slide #20), suggesting that silicate lavas, as opposed to molten sulfur, could exist within lava lakes on Io.
Photograph courtesy of P. Mouginis-Mark.