Introduction

Abstract

Near—Earth objects (NEOs) are our closest celestial companions in the Solar System—yet there are major open questions around NEOs, their orbital dynamics and physical and chemical properties as celestial bodies. The difficulties mostly arise because of the close approaches, which introduce mathematical singularities in the equations of motion, require very accurate orbits to be modelled, and result in strongly chaotic behaviour; yet it is precisely because of the possibility of close approaches, and even of collisions, that these objects are of special interest. The following seven articles offer views to the celestial mechanics of asteroids, comets, and meteoroids approaching our planet.