COMETS DISGUISED AS ASTEROIDS

Comets and asteroids were previously thought to be two completely dist inct groups of solar-system objects, with marked contrast in both phys ical and dynamical characteristics. A comet is operationally defined b y the presence of a coma, while an asteroid has no coma. However, rece nt observations have shown that comets can sometimes take on asteroida l appearances and even asteroidal photometric behavior. Thus the obser vational distinction between comets and asteroids is not as clear cut as it once seemed. The possible presence of comets hidden among known asteroids forces us to reconsider the criterion by which we distinguis h comets from asteroids and possibly our inventory of both comet and a steroid populations.