Dwarf Planets in the Extreme Outer Solar System (Infographic)

Details of the cold objects that orbit far from the sun.

The solar system has four main regions. Rocky planets like Earth orbit near the sun, out to a distance of 4.2 A.U. (An A.U., or astronomical unit, is the distance from Earth to the sun.) Farther out lie the gas giants, out to 30 A.U. Next is the frozen Kuiper belt beyond Neptune, out to 50 A.U. Far beyond that is the Oort Cloud, a region of icy bodies that extends halfway to the nearest star.

But new discoveries suggest that this map is incomplete. Dwarf planets like Sedna and the newfound 2012 VP113 occupy a realm beyond the Kuiper belt scientists are calling the "inner Oort Cloud." Sedna and 2012 VP113 have very eccentric, or oval-shaped, orbits. They also have very distant perihelions (closest approach to the sun). This sets them apart from all the other known objects in the solar system.

Sedna’s highly eccentric orbit carries it from 76 A.U. at its closest to the sun, out to 937 A.U. at its most distant. 
 
The object 2012 VP113 has a similar orbit. One Sedna orbit takes 11,400 Earth years to complete.
 
Anomalies in the orbits of Sedna and 2012 VP113 tantalizingly suggest that one or more giant planets 10 times the mass of Earth could orbit in the dark, frozen outer fringe of our solar system, 250 A.U.s or more from the sun.
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