Solar and stellar flares due to impacts of comet nuclei and falling evaporating bodies, FEBs, with the Sun/stars are analytically considered. It is shown that impacts of sun/stargrazing comets will be accompanied by essential aerodynamic effects: nuclei crushing and expansion/ flattening of crushed mass within the chromosphere. These processes lead to impulse generation of a hot plasma, strong shock wave in the thin layer near photosphere, eruption of the hot ionized clump to the lower corona, i.e., impact-induced solar/stellar flares.
