In this category, planets are astronomically defined as celestial bodies that orbit around a star, have adequate mass to achieve hydrostatic equilibrium (i.e. spherical form), and have "cleared the neighbourhood" around their orbits. Dwarf planets are non-satellite bodies that fulfill only the first two of these criteria. Planetoids fulfill only the first. Nomad planets are planetary-mass bodies that have either strayed out of their star systems or were never gravitationally bound to one.
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