Yup, we’re up to eleven planet-class bodies in the solar system. Yesterday, Chad Trujillo, an astronomer at Gemini Observatory in Hilo, Hawaii and Scott Sheppard, an astronomer at the Carnegie Institution for Science in Washington DC, published their discovery in Nature, adding a new neighbor for Sedna, the Dwarf Planet living around the Oort cloud that was discovered a decade ago, and put into the class of bodies that Pluto was “demoted” into with such controversy.
Formally known as 2012 VP113, and informally as “Biden” (get it, because he’s the VP?!?!), the likely hunk of ice is about 450 km in diameter, and flies in an orbit so far flung, it takes more than 4,000 Earth-years for it to make one trip around the sun. In fact, Biden and Sedna’s orbits are so elliptical (rather than circular), some astronomers are wondering if there’s something out there affecting them that we haven’t discovered yet. Like, as Phil Plait suggests is at least a slight possibility, another planet the size of Earth. Wouldn’t that be a kicker?
[Update: It was pointed out by people smarter to me that there are already five formally recognized dwarf planets, including Pluto, and another six in the "very likely" category, to which we can add Biden. However, we haven't been ably to study them closely enough yet to nail down their classifications, so things are, as they say, in flux.]