Lost Comet

Not a mythic origin: the category arises from modern observational astronomy and orbit determination practices. A comet becomes categorized as 'lost' when historical observations established a periodicity and a predicted return is not observed at the expected perihelion passage, leading cataloguers and orbit specialists to record it as unlocated or presumed disappeared.

No folkloric or iconographic appearance. When observed, these objects display the ordinary features of active comets (nucleus, coma, tail) recorded in earlier apparitions; the 'lost' label indicates that the object was not detected at a subsequent predicted return and thus lacked a recent observed appearance.

Not sentient. The phenomena underlying the status are physical processes: orbital perturbations (especially by giant planets) altering predicted returns, nongravitational forces from outgassing altering orbital motion, fading or exhaustion of volatiles leading to low brightness or transition to an inert body, physical disintegration or fragmentation during perihelion passages, and collisions (e.g., impacts with planets) that remove the object from expected returns. These natural processes explain why a previously observed comet can become unlocatable.