Dormant phases in the aging of periodic comets

Abstract

Implications of the observations of P/Halley for the problem of comet aging are discussed. It is suggested that the active lifetimes of short-period comets are intermitted by dormant phases during which they remain completely, or almost completely, inactive. Such phases are tentatively identified for several short-period comets by the absence of observations of their prediscovery apparitions at which they should have been very bright and favourably placed.