This balance lasted a while, but the conflict between Galmon Empire and Bolar Federation caused a powerful missile to plummet into the Sun. As a result, irregular fusion pattern developed and the Sun was quickly transforming into a red giant that emits devastating heat. As a result, the Humans once again, has to take shelter in the underground city as the heat becomes unbearable. Upon the Yamato's return with weapon from Gratiana that reversed the effect of the missile, the planet was once again hospitable.