In Greek mythology, Phaethusa ("radiance") was a daughter of Helios and Neaera, the personification of the brilliant, blinding rays of the sun. With her sister, Lampetia, she guarded the cattle of Thrinacia[?].
... enough, for example after starting it with a short rip string or by a snap of the thumb, a person holding it in her hand can accelerate the gyroscope to incredibly high revs ...