It’s time to have a talk about dwarf planets. Everyone’s always acting like Pluto’s demotion is a horrible thing, and now we find out that the dwarf planet 2007 OR10 is the largest unnamed object in our solar system. It’s 955 miles across, and all it gets is a boring string of numbers and letters? This, from the species that worked itself up into a lather over the name of a polar research vessel? Dwarf planets have feelings too!
Well, to be fair, it’s a little more complicated than that. There are a lot of rules for naming objects in space, dwarf planets included. The International Astronomical Union requires that a body’s name reflects its characteristics, and that trans-Neptunian objects get names derived from creator deities. That’s how Makemake went from being called Easter Bunny to bearing the name of an Easter Island fertility god.
Until just recently, scientists just haven’t known enough about 2007 OR10 to give it a full-fledged, permanent moniker. When it was discovered in 2007 by then-grad student, Meg Schwamb, her professor and famous “Pluto Killer” Mike Brown did give it nickname: Snow White, because he thought it would be icy and white, like fellow dwarf planet Haumea. Though it feels kinda like a half-baked dwarf joke to us.
Now Brown has a lot more information to base his nickname on. New data from the Kepler space telescope, in combination with older information from the Herschel Space Observatory, has revealed that 2007 OR10 is significantly larger than originally estimated, making it the third largest known dwarf planet. It also has one of the slowest rotation periods of any object spinning around the Sun (one 2007 OR10 day is 45 hours long). And its surface–sorry, Brown–is actually very dark for a dwarf planet.
This Kepler/Herschel tag team worked because each observatory has different strengths: The Kepler telescope measures the fraction of sunlight reflected by 2007 OR10, and Herschel measures the fraction of sunlight absorbed and then sent back out as heat. That gave scientists a much better idea of 2007 OR10’s total brightness, which is pretty key when trying to figure anything out about distant and dim objects like dwarf planets.
According to Geert Barentsen, a research scientist at NASA’s Ames Research Center who works on Kepler, this probably wouldn’t have happened if things hadn’t gone a bit sideways with the Kepler mission. Two and a half years ago, the spacecraft lost one of its wheels, a stabilizing device similar to a gyroscope. That could have been the end of Kepler’s space-hunting days, “but our engineers figured out that if you point the space craft toward the sun in such a way, the solar radiation pressure will keep it perfectly stable,” says Barentsen. “This is a byproduct of having to realign the mission. We had a broken spacecraft, and suddenly we got all this science, so we’re very excited.”
And it’s not just the prospect of naming 2007 OR10 that has scientists’ attention. The more they find out about full-blown planets’ teensier cousins, the more they find out about the solar system’s past. “Dwarf planets are a whole new world we’re just beginning to characterize. The hope is to register many more, to find patterns,” says Barentsen. “These are primordial objects. They’re a model for the solar system.”
But on the micro level, this is also just a nice day for 2007 OR10, which was in dire need of a catchier name. It’ll just take a little bit longer for the astronomers to finalize the paperwork.