With 4,826 confirmed planets and Kepler candidates and the discovery of a gas giant with a colossal system of 160 rings, it may seem like we know quite a bit about what is out there in the cosmos. However, the universe loves to confuse us, and—frankly—humanity has yet to come to grips with what is in our own solar system.
90482 Orcus is a Kuiper belt object with almost exactly the same orbital period, inclination, and distance from the Sun as Pluto.
Both Pluto and Orcus also share a 2:3 resonance with Neptune, although Orcus is oriented differently. Not only are their orbits almost identical, but they both have moons that are very large relative to their size. Pluto’s moon Charon is half the size of Pluto, and Vanth has been estimated to be one-third the size of Orcus.