has_part has part has part overlaps overlaps construction manufactured product astronomical body part biosphere technosphere A part of an astronomical body which includes, as parts, all the entities which have been constructed or manufactured by humans or their technology and which are within the gravitational sphere of influence of that body. The gravitational sphere of influence referenced in this class' definition is the Hill sphere: a region in which an object dominates the attraction of satellites despite gravitational perturbations. An environmental system which includes, as parts, all the entities which have been constructed or manufactured by humans or their technology within the gravitational sphere of influence of an astronomical body. envoAstro