The triboluminescence intensity from stress-activated Sr3Al2O6:Eu,Dy (SAO-ED) was so strong that we could see it with the naked eye in the atmosphere. The luminescence integrated intensity was about five hundred times as high as that of crystal sugar. We think that the light emission is due to the movement of dislocations and the 4f7–4f65d transition in the doped Eu2+ ions from the analysis of the emitted light. Furthermore, we have discovered the new phenomenon that the luminescence intensity of the SAO-ED is recovered by the irradiation of ultraviolet light.