Astronomers just announced the discovery of a dwarf planet that trumps Sedna as the object in our solar system most distant* from our sun. However, what's potentially more interesting is what the planet's orbit suggests: another giant, rocky world at the far edge of our Solar System.

But let's start with what we do know. The newly discovered dwarf planet—dubbed 2012 VP113, for now—is only 280 miles-wide but is a whopping 7.4 billion miles from the Sun. That makes its orbit obscenely long. It takes over 4,000 years for it to circle the Sun just once. The new dwarf planet is slightly further away than Sedna (pictured in the artist's rendition below), but it might not be the furthest object from the Sun for long.

The odd alignment of 2012 VP113's orbit actually suggests that there's something massive even further out. Based on their measurements, astronomers think it could be a rocky planet about ten times the size of Earth. Such a world would not have been noticed by NASA's Wide-field Infrared Survey Explorer (WISE) which scoured the area a couple years ago in search of the elusive Planet X, because it wouldn't generate enough heat for the telescope to notice it.


Of course, there are other explanations for 2012 VP113's orbit. The news is nevertheless exciting because it offers more clues about what's going on in the Oort Cloud, that cluster of rock and ice that's floating millions of miles beyond Neptune. It's actually getting kind of crowded out there. [Nature via Discover]

* As Slate's Phil Plait points out, 2012 VP113 isn't always the most distant object: "Let me point out that Sedna actually gets much farther from the Sun than VP113 ever does, but at their closest points VP113 is farther away."


Top: 2012 VP113 is pictured among the stars in the background. Above: The new dwarf planet is shown in red, green, and blue in three different spots during its orbit.