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No Planet 9? Small-body Pile-up Could Explain Odd Orbits

11 Jun 2018, 15:56 UTC
No Planet 9? Small-body Pile-up Could Explain Odd Orbits NASA/JPL-Caltech

Astronomers have been struggling to explain the orbits of 30 or so bodies at the outer rims of the solar system, called “detached objects.” These worlds are smaller than Pluto and travel in elliptical trajectories around the Sun.

Sedna is one of the most well-known detached objects: a reddish world found in 2003, it’s one-third the size of the Moon and has an orbital period of 11,400 years — the longest of any object known in the solar system. At closest approach it passes 76 times farther away than the distance between the Sun and Earth. At its farthest, it goes more than 900 times that distance.

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