Kuiperian Type Planetoid
Image from John M Dollan
Ice dwarf; Planetoid Class. Found in the outer reserves of a solar system, these are the remnants of planetary formation. Some may migrate into closer orbits. Others may be trapped as outer planet moons, while some may form as moons originally.

Kuiperian worlds are those that have formed in the extreme outer regions of a solar system, where the materials are so rare that they never had a change to grow very large. They are also considered to be representative of the proto-planetary disk, largely unchanged since their initial formation. As such, scientifically, they are of great interest. They are also excellent sources for volatiles, being composed primarily of water and other ices. For the most part, these bodies are confined to a specific region, called the Kuiper belt, typically ranging out to and beyond 40 AU from the parent sun. As such, these regions are highly vulnerable to gravitational influences of stellar close encounters. Occasionally, two suns will pass close enough to allow for the swapping of Kuiper objects. Such transferred worlds are found in highly eccentric orbits, making them potential objects for further gravitational disturbing by the other bodies of that solar system. Indeed, in a system where there are such orbital oddities, once every ten thousand years sees the approach of a Kuiper object to the inner solar system, forming a truly massive and tremendously bright comet.
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Development Notes
Text by John M. Dollan in his Planetery Classification List
Initially published on 31 December 2007.