Two months ago, scientists at the Palomar Observatory in California announced that they had discovered a tenth planet in the far reaches of the Solar System. The planet, nicknamed Xena but officially known only as 2003UB313, is half again larger than Pluto, and is 9 billion miles away, three times as far from the sun as Pluto.
This week comes the news that 2003UB313 has a moon. The newly discovered satellite of 2003UB313 is 155 miles wide, and in a move that will thrill the fans of the warrior princess, has been nicknamed Gabrielle.
Sticklers are arguing about whether 2003UB313 ought to really be designated as a planet. These same people say that Pluto is not a planet, because it is too small, and is really just an icy object from the Kuiper Belt.
I say that these niggling astronomers ought to remember that the designation of what is and what is not a planet is subjective. There is no definition of a planet that is inherent to the cosmos, objectively measured and inflexible. The word “planet” is an arbitrary name we give to large objects that are not stars in the night sky. It’s a word that predates science, and was coined well before reasonable people agreed that the planets revolve around the sun.
If the public wants 2003UB313 to be called a planet, call it a planet. Give the big icy lump a real name and get on with it. If they want the funding for their research to continue, astronomers need to get back in the game of communicating the excitement outer space, and remember that there is nothing wrong with scientists speaking a bit of common English every now and then.
Annoying in Science class, though.
“Of course, when we say “planet” we don’t mean it in the scientific sense, but in the common English sense. Normally. If you get an exam question on it… Well… Guess.”
Meanings change over time. Some get less specific, some get more specific, I don’t think anyone needs to complain about it.
No one says “slapstick” these days and actually means a slapstick (a thing used to slap a drum as a cue for laughter at plays), and no one suffers from it. It’s now an adjective, not a noun; that’s a big change for a word.
That said, some words have two meanings stemming from the same original word, like “albino”, which has the general use of refering to an animal lacking colour (often resulting in creamy-white skin and red eyes), and the official scientific term refering to people with albino genes in them, which can be applied to just about anyone with fair hair and/or blue eyes.
It makes things a lot easier for scientists to not have to go into detail every time they want to be specific, so it’s not surprising they have words with a lot more meaning put to them. The general public, however, are unlikely to bother themselves with it any time soon, so what’s most likely to happen is…
Scientists will debate for a bit before making up their minds and then debate a bit longer.
Everyone else will just call it a planet.