(The object formerly known as) Snow White and the Seven Dwarfs

With 2016 over and 2017 well underway, we'll soon be coming up on the 10th anniversary of the discovery of 2007 OR₁₀, a dwarf planet that orbits out past Pluto in the scattered disk. When OR₁₀ was first discovered in July of '07, it was bright enough that it was clearly either fairly large (i.e., a dwarf planet) or almost completely white, so Mike Brown and his associates assumed the latter and nicknamed it “Snow White”. Later observations made it clear that it was actually quite large and quite red, so the nickname no longer made sense, and was dropped. With OR₁₀'s discovery now ten years after the fact, it's time for this distant world to join the ranks of the named dwarf planets, and time is running out for Mike Brown's team to pick a new name.

Is OR₁₀ really a dwarf planet?

I've written before (and so has Mike Brown) about the fact that the IAU created the “dwarf planet” category, officially added a few members to the club, and then essentially closed the books on it, leaving an entire generation of children to learn that the solar system has eight real planets and exactly five official dwarf planets. The reality, of course, is that we now know about at least fifty dwarf planets, and possibly hundreds, with more being discovered all the time. There are lists out there of possible and probable dwarf planets, most of which agree on a number of objects that almost certainly are dwarf planets. One simple—and certainly the most conservative—solution to the question of what to call a dwarf planet is to say that since Ceres is officially a dwarf planet, anything larger than Ceres must also be a dwarf planet. If we use this overly conservative threshold for dwarf planets, OR₁₀—which is 63% larger than Ceres—clearly makes the cut, along with a total of seven other dwarfs (including Ceres).

Snow White OR₁₀ and the seven (other) dwarfs

• Pluto–Charon
• Eris
• 2007 OR₁₀
• Makemake
• Haumea
• Quaoar
• Sedna
• Ceres

When astronomers realized that OR₁₀ was big rather than just bright, they also realized that it is actually one of the largest objects orbiting the sun, with initial estimates putting it between Makemake and Haumea—both “official” dwarf planets—in size. More recent estimates put OR₁₀ as possibly larger than Makemake, which would make it the third largest known dwarf planet, and place it within the top twenty largest objects in the entire solar system! (Even OR₁₀'s newly discovered moon is fairly large, beating out all but the top seven main-belt asteroids in size.)

A rose by any other name…

Despite being the third-largest known dwarf planet, 2007 OR₁₀ conspicuously lacks a name. In fact, it's the largest unnamed object in the solar system! In the ten years since its discovery, amateur astronomers and space enthusiasts have proposed plenty of ideas—everything from Norse, British, and Aztec deities to ‘Prince’ (Get it? The artist formerly known as Prince—the object formerly known as Snow White?) to a number of variations on ‘Orten’ (Orten, 'Orton, Horton, etc.—all based of course on the temporary designation OR₁₀). While it's true that not having a name doesn't really change anything about OR₁₀ itself, it definitely downgrades it in the eyes of the public, resulting in many lay publications happily mentioning Quaoar, Sedna, and Orcus as possible dwarf planets but completely ignoring OR₁₀, despite the fact that it is significantly larger than any of them. It's likely that this total silence around OR₁₀ is at least partially due to it's lack of a name.

The clock is ticking for Mike Brown's team to choose a name for OR₁₀; the IAU's official rule is that after ten years, anyone can submit a name for official consideration. Since OR₁₀ was discovered in July of 2007, there are only a few months left for a name to be submitted, considered, and approved. While I'd love to submit my own ideas and possibly even be the one to name a dwarf planet, what I'd really love would be for that honor to go to the discoverers instead. Both Mike Brown and Meg Schwamb (whose research under Mike Brown actually led to OR₁₀'s discovery) have stated publicly that they now have enough information to name OR₁₀; hopefully it won't be too long before the third largest dwarf planet finally has a name of its own.