Ceres was once thought to be a member of an asteroid family . The asteroids of this family share similar proper orbital elements , which may indicate a common origin through an asteroid collision some time in the past . Ceres was later found to have spectral properties different from other members of the family , which is now called the Gefion family after the next @-@ lowest @-@ numbered family member , 1272 Gefion . Ceres appear to be merely an interloper in the Gefion family , coincidentally having similar orbital elements but not a common origin .