what kind?
Pluto is protected by its 2:3 orbital resonance with Neptune.
Pluto
 However, Pluto is also protected by its 2:3 orbital resonance with Neptune: 
what is pluto? A dwarf planet in the Kuiper belt. who discovered it? Clyde Tombaugh when? 1930 what is its origin? One early hypothesis was that Pluto was an escaped moon of Neptune. what is its mass? 17.7% that of the Moon. what is its size? Its surface area is , or roughly the same surface area as Russia. what kind of atmosphere does it have? It has a tenuous atmosphere consisting of nitrogen (N), methane (CH), and carbon monoxide (CO). does it have a moon? UNANSWERABLE does it have a relation with any other planet? Yes, with Neptune.
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Pluto [SEP] Relationship with Neptune
The minimum separation between Pluto and Neptune actually occurs near the time of Pluto's aphelion.