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Ownership: UCP
System: Sol system
Type: Dwarf planet
Location: Alpha Quadrant

An object in the outer Sol system, Sedna is over 1000 kilometers in diameter. An object this large cannot have formed by accretion in the tenuous regions of the protoplanetary disk corresponding to its current location. Sedna must have formed elsewhere, presumably amongst the planets or in the Kuiper Belt, and been ejected outwards. Lastly, its perihelion was lifted out of the range of Neptune.

The orbit and the size attest to an early epoch in which strong gravitational scattering events rearranged the small bodies of the solar system. Sedna could be a member of a substantial population of bodies trapped between the Kuiper Belt and Oort Cloud. These would have been emplaced at early times.

Some data suggests Sedna may have a companion object of its own.


Sedna has a perihelion of 76 AU, well beyond the orbit of Pluto. The orbit is similar, dynamically, to 2000 CR105 which has perihelion at 44 AU, also outside Neptune's reach. Other objects have larger aphelia than Sedna's 990 AU (e.g. Kuiper Belt Object 2000 OO67, with aphelion at 1010 AU) and many comets travel to larger distances. Sedna is interesting because of its perihelion distance.

Sedna's orbit is so long it takes over 10,000 standard years to complete one round.