Comets in orbit around stars may be highly eplitical rather than circular ( such as planets ) which takes them past the orbit of pluto. Some mass of the comet will sublimate with each pass by the sun and after many passes the comet may no longer be active and be simply an asteroid. | Comets in orbit around stars may be highly eplitical rather than circular ( such as planets ) which takes them past the orbit of pluto. Some mass of the comet will sublimate with each pass by the sun and after many passes the comet may no longer be active and be simply an asteroid. |