Day 17 of the A-to-Z Challenge. Q is for Quaoar, an object in the outer solar system. Discovered in 2002 and named after a deity from Tongva mythology, Quaoar arrived on the astronomical scene during a period of turmoil. You see, it was not alone…
In 1992 (right around the time I was in grade school, possibly learning the mnemonic “My Very Educated Mother Just Showed Us Nine Planets”), astronomers discovered an object that received the provisional name
1992 QB1. This object turned out to be the first Trans-Neptunian object discovered since Pluto (and its moon Charon).
This prompted a renewed effort to locate similar objects, which came to be known as
cubewanos (QB1-ohs). It turns out, there are a lot of similar objects in the outer solar system. In 2000, astronomers discovered the object that was eventually named Varuna. Less than two years later, Quaoar was discovered, and it was pretty big. Bigger than
Many other Trans-Neptunian Objects were found during the first few years of the 21st century. Some of them rival Pluto in size — and the discoverers naturally wanted their discoveries classified as planets. “I discovered a planet” is an impressive quote: it fits on a business card or a t-shirt, and it’s a real hit as a pick-up line.
Were Quaoar, Ixion, Sedna, Haumea, Makemake, and the other objects on the growing list of Trans-Neptunian Objects really planets? No one could say, because the International Astronomical Union had never officially defined the word
Then in 2005, the same group that discovered Quaoar discovered another object — and it was as big as Pluto, or bigger. Obviously, if Pluto is a planet, then the new object must also be a planet, right? (This object received the rather fitting name of
Eris — the goddess of discord, who causes arguments.)
A similar crisis had arisen two centuries earlier: astronomers discovered Ceres, and decided it was a planet… then discovered Pallas, Juno, Vesta, etc. The solution then was to create a new classification: these objects would be known as
minor planets, though most people just call them asteroids.
In 2006, the IAU decided to resolve the issue with a similar
cop-out solution, creating a definition for
planet that deliberately excluded these new objects — along with Pluto — but then creating a new classification of
dwarf planet. Pluto and Eris (along with Ceres) were specifically called out as dwarf planets.
(As a consolation to Pluto, the IAU also created the classification of
plutoid, which at the time they vaguely defined as anything kinda like Pluto.)
After the IAU vote, our solar system was one planet lighter, and astronomers were free to continue discovering inconveniently large objects without fretting over whether they were planets.
But really, Quaoar doesn’t care about the arguments, the disputes over definitions, or the glory of planethood. Quaoar doesn’t care whether we call it a planet, dwarf planet, Trans-Neptunian Object, cubewano, or late for dinner. Quaoar just is.
1992 QB1? It’s still just called