The impact hazard of near-Sun comets

There are several groups of comets with perihelion near the solar surface known. Of these, the Marsden and Kracht groups move in orbits situated in a spatial corridor of the daytime Arietid meteoroid stream. The orbits of comets of the Meyer group are not very different from those of the Marsden and Kracht groups; for the purpose of our study, we thus consider a common Meyer-Marsden-Kracht (MMK) group. Since Arietids pass close to the Earth's orbit, comets of the MMK group must also do so. We study the close approaches of the orbits of these comets with regard to the proximity of the orbit of our planet and estimate an impact hazard. We found a concentration of approaches within an interval of solar longitude from similar to 72(O)-84(O) (between June 2 and June 15). The mean time between two collisions of an MMK comet and Earth is estimated to be one to two million years, assuming a steady state during that period.