What would the ratio of surface brightnesses be if the temperature were 2,000 k instead of 6000 k? in other words, call the two surface brightnesses sbnow and sbhot, corresponding to the surface temperatures of 6000 k and 2,000 k, respectively. then you want to find the ratio sbhot/sbnow. show your work. remember that the equation for surface brightness (power per square meter) is given by sb= σt4, where σ is a constant and t is the surface temperature of the object. this problem is much easier if you realize that if you have a fraction like x /y it is the same as (x/y) .