Close Encounters of Minor Bodies with the Earth

This paper contains the statistics of close encounters of observed minor bodies with the Earth. Five classes of small objects have been examined, namely: near-Earth asteroids (Aten, Apollo, and Amor), short-period comets, and long-period comets. The motion of objects belonging to the first four classes has been integrated over a time span of 821.4 years, while the motion of long-period comets has been followed for 60 years, centered on the discovery epoch. The behavior in time of the minimum orbit intersection distance (MOID) is studied, and frequency curves of close passages according to the distance from Earth are provided and discussed.