This Dwarf Planet is the Largest Unnamed Celestial Body in the Solar System

If you discovered a dwarf planet, what would you name it? Something cool like "Unicron"? Something nerdy like "Gimli"? Or would you let that poor little planet drift through space, nameless for more than a decade?

In 2007, astronomers Meg Schwamb, Mike Brown, and David Rabinowitz observed an unknown object in their search for distant solar system bodies. Their discovery, a dwarf planet designated 2007 OR10, measures 955 miles (1,535 kilometers) in diameter and appears deep red in color. Despite its impressive stature, it remains the largest known celestial body without a name.

A Class Of Their Own

Like their name suggests, dwarf planets are petite compared to the other planets in the solar system and are typically even smaller than Mercury. The International Astronomical Union adopted the term in 2006 after discovering objects with similar masses as Pluto beyond Neptune. Consequently, Pluto became re-classified from planet to dwarf planet, with scientists recognizing its impact on science by designating dwarf planets beyond Neptune as "plutoids." Along with Pluto, four other dwarf planets—Ceres, Eris, Makemake, and Haumea—have been officially recognized, but it's possible that over 200 have yet to be discovered.

Current IAU standards define dwarf planets as celestial bodies that orbit the sun, are round or nearly round (spherical or "potato"-shaped are also acceptable), and are not satellites or moons. Unlike planets, which have cleared the area around their orbits, a dwarf planet may cross paths with objects such as asteroids in their rotation around the sun. 2007 OR10 meets all of these criteria, but scientists still haven't given it a proper name.

Taken in 2009 and 2010, reveal a moon orbiting the dwarf planet 2007 OR10. Each image, taken by Hubble’s Wide Field Camera 3, shows the companion in a different orbital position around its parent body.

A Dwarf By Any Other Name

Ten years post-discovery may seem like a long time to wait for an official name beyond a series of letters and numbers, but astronomers have their reasons for deliberating. Unlike naming a puppy or a goldfish, a dwarf planet can't be named out of feelings or spontaneity, or after a favorite rock star or superhero (yet). Instead, groups dedicated to Small Body Nomenclature (CSBN) and Planetary System Nomenclature (WGPSN) work together to come up with names related to a deity or mythology. For example, the plutoid Haumea, was named after the Hawaiian goddess of fertility and childbirth. Often, the name will correspond to a physical characteristic of the dwarf planet.

Since its discovery in 2007, astronomers haven't felt like they've uncovered enough about 2007 OR10 to give it a proper name. In fact, they recently learned that it's much larger than they originally thought (likely due to a layers of ices of methane, carbon monoxide and nitrogen), making it the third largest of the known dwarf planets. According to Schwamb, these new discoveries have accelerated the naming process, so with any luck, 2007 OR10 will be dubbed something a little more glamourous sometime soon. Let's hope it's something more evocative than "Jeff."

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Written by Jamie Ludwig July 1, 2017

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