The phrase refers to an orbiting body (a planet or protoplanet) "sweeping out" its orbital region over time, by gravitationally interacting with smaller bodies nearby. Over many orbital cycles, a large body will tend to cause small bodies either to accrete with it, or to be disturbed to another orbit, or to be captured either as a satellite or into a resonant orbit. As a consequence it does not then share its orbital region with other bodies of significant size, except for its own satellites, or other bodies governed by its own gravitational influence. This latter restriction excludes objects whose orbits may cross but that will never collide with each other due to orbital resonance, such as Jupiter and its trojans, Earth and 3753 Cruithne, or Neptune and the plutinos.[3] As to the extent of orbit clearing required, Jean-Luc Margot emphasises "a planet can never completely clear its orbital zone, because gravitational and radiative forces continually perturb the orbits of asteroids and comets into planet-crossing orbits" and states that the IAU did not intend the impossible standard of impeccable orbit clearing.[2]
The Sun, a spectral class G2V main-sequence star
The inner Solar System and the terrestrial planets
Mercury
Mercury-crossing minor planets
Venus
Venus-crossing minor planets
524522 Zoozve, Venus' quasi-satellite
Earth
Moon
Near-Earth asteroids (including 99942 Apophis)
Earth trojan (2010 TK7)
Earth-crosser asteroids
Earth's quasi-satellites
433 Eros
Mars
Deimos
Phobos
Mars trojans
Mars-crossing minor planets
Asteroids in the asteroid belt, between the orbits of Mars and Jupiter
Ceres, a dwarf planet
Pallas
Vesta
Hygiea
Asteroids number in the hundreds of thousands. For longer lists, see list of exceptional asteroids, list of asteroids, or list of Solar System objects by size.
Asteroid moons
A number of smaller groups distinct from the asteroid belt
The outer Solar System with the giant planets, their satellites, trojan asteroids and some minor planets
Jupiter
Rings of Jupiter
Complete list of Jupiter's natural satellites
Galilean moons
Io
Europa
Ganymede
Callisto
Jupiter trojans
Jupiter-crossing minor planets
Saturn
Rings of Saturn
Complete list of Saturn's natural satellites
Mimas
Enceladus
Tethys (trojans: Telesto and Calypso)
Dione (trojans: Helene and Polydeuces)
Rhea
Rings of Rhea
Titan
Hyperion
Iapetus
Phoebe
Shepherd moons
Saturn-crossing minor planets
Uranus
Rings of Uranus
Complete list of Uranus's natural satellites
Miranda
Ariel
Umbriel
Titania
Oberon
Uranus trojan (2011 QF99)
Uranus-crossing minor planets
Neptune
Rings of Neptune
Complete list of Neptune's natural satellites
Proteus
Triton
Nereid
Neptune trojans
Neptune-crossing minor planets
Non-trojan minor planets
Centaurs
Damocloids
Trans-Neptunian objects (beyond the orbit of Neptune)
Kuiper-belt objects (KBOs)
Plutinos
Orcus, a dwarf planet
Vanth
Pluto, a dwarf planet
Complete list of Pluto's natural satellites
Charon
Twotinos
Cubewanos (classical objects)
Haumea, a dwarf planet
Namaka
Hiʻiaka
Quaoar, a dwarf planet
Weywot
Makemake, a dwarf planet
(307261) 2002 MS4
120347 Salacia
20000 Varuna
Scattered-disc objects
Gonggong, a dwarf planet
Xiangliu
Eris, a dwarf planet
Dysnomia
(84522) 2002 TC302
(87269) 2000 OO67
V774104
Detached objects
2004 XR190
2012 VP113 (possibly inner Oort cloud)
Sedna, a dwarf planet (possibly inner Oort cloud)
Oort cloud (hypothetical)
Hills cloud/inner Oort cloud
Outer Oort cloud
I get real hot and heavy when my wife goes into science mode and goes off. Like she memorized much of the periodic table. Or when she's able to break down food ingredients by their structure.