  We consider the lifetimes of spots on the Sun and other stars from the
standpoint of magnetic diffusion. While normal magnetic diffusivity predicts
lifetimes of sunspots that are too large by at least two orders of magnitude,
turbulent magnetic diffusivity accounts for both the functional form of the
solar empirical spot-lifetime relation and for the observed sunspot lifetimes,
provided that the relevant diffusion length is the supergranule size. Applying
this relation to other stars, the value of turbulent diffusivity depends almost
entirely on supergranule size, with very weak dependence on other variables
such as magnetic field strength and density. Overall, the best observational
data for other stars is consistent with the extension of the solar relation
provided that stellar supergranule sizes for some stars are significantly
larger than they are on the Sun.
