Similarity solutions determine the profiles of density and temperature from impacts, which determine the scaling of the temperature and optical depth on material parameters, time, screening, and impactor size. This note uses scaling results derived earlier for the growth, size, and temperature produced by impacts to discuss the radial temperature profiles they produce. While the plasmas cool in milliseconds, they offer unique information about the thermodynamic state and material properties of the target material. The brightness temperature can be estimated from known two-dimensional similarity solutions. Regions close to unit optical thickness contribute effectively to the radiation, hence, they determine the plasma brightness temperature. The estimates of temperature as a function of time can be combined with the estimates of the exit hole size to estimate the total observable signal, which should be readily observable from distances of hundreds of kilometers.