near-Earth object
Solar System object whose orbit brings it into proximity with Earth
Comet Encke
periodic comet
Halley's Comet
short-period comet visible from Earth every 75–76 years
potentially hazardous object
asteroid or comet with an orbit such that it has the potential to make close approaches to the Earth
Near-Earth asteroid
objects in a near-Earth orbit without the tail or coma of a comet