“He loves me. He loves me not,” is an incantation traditionally recited while plucking the petals of a daisy until the last remaining ray of the “day’s eye” reveals the answer. If you removed the star-like rays of an aster in the same manner would you create a “disaster”?
“Disaster,” like “aster,” refers to a star. It dates from a time when many believed the stars in the heavens affected the lives of those below. “Disaster” came into English in the late 16th century from Italian disastro ‘ill-starred event,’ from dis- (expressing negation) + astro ‘star’ (from Latin astrum). At first it meant ‘an unfavorable aspect of a star or planet,’ as in the first scene of Hamlet, when Horatio speaks of, “…stars with trains of fire and dews of blood, Disasters in the sun; and the moist star…” It soon came to mean, as it does today, ‘an occurrence of ruinous or distressing nature; a sudden or great misfortune, mishap, or misadventure; a calamity.’
I guess we can call “disaster” another “lonely negative,” since the aster flower, though lovely, is not the opposite of disaster.