That would have just been an object that had been in a circular orbit around the Sun in that region of icy bodies, had gotten a little bit too close to Neptune one time, and then got slingshot out and is now on its way back in.
태양 주변을 도는 얼음지대에 무언가 태양주변을 도는 물체가 있었는데 언젠가 해왕성에 너무 근접해  튕겨나갔다가 다시 돌아오고 있는 겁니다.