Phaethusa  In Greek mythology, Phaethusa or Phaëthusa ( "Phaéthousa", "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. She carried a copper staff with which she tended to her father's herd of sheep. She is listed as among the Heliades.