No, Virginia, there are only 8 planets

CNN is running a “heartwarming” human interest piece about a fourth grader who came up with a mnemonic to help “those having trouble remembering the newly assigned 11 planets” as part of a National Geographic contest. Unfortunately, the contest, and thus the mnemonic, are wrong. It’s too bad they didn’t consult an astronomer before running with it. Here’s the mnemonic she came up with:

Her award-winning phrase is: My Very Exciting Magic Carpet Just Sailed Under Nine Palace Elephants.

The 11 recognized planets are Mercury, Venus, Earth, Mars, Ceres, Jupiter, Saturn, Uranus, Neptune, Pluto and Eris.

Ignoring the literary merits of her mnemonic (though personally I think “Pallid” would be a better replacement for “Palace”), it’s wrong because there are actually only eight planets. Ceres, Pluto, and Eris are dwarf planets. Where the contest got confused is they think that dwarf planet is a sub-classification of planet; it is not. According to the three-way classification system now in use, there are three entirely separate classes of solar system bodies: planets, dwarf planets, and small solar system bodies (SSSBs). At the time of the new definition in 2006, the International Astronomical Union took a bit of flak for putting the word “planet” in the name of the “dwarf planet” category because it has potentially confusing to laymen. It’s looking like those concerns were valid.

Now don’t think I’m just picking nits here. There’s another reason this mnemonic is untenable: it only includes the currently recognized dwarf planets. But there are dozens and dozens of likely dwarf planet candidates out there we simply haven’t officially classified yet (42 in the Kuiper Belt at last count alone). The definition of dwarf planet, an object that “has sufficient mass so that it assumes a hydrostatic equilibrium (nearly round) shape” (and is not a natural satellite), is pretty darn inclusive, and was intended to be. Its purpose is to fit in all of the large round objects that don’t make it into the exclusive planetary club. For example, here are a few of the objects in the solar system that are likely to be classified as dwarf planets in the near future: 2003 EL61, Sedna, 2005 FY9, Quaoar, Orcus, and Ixion. Some of these names will be familiar if you’ve been keeping up on your astronomy news. Note that all of them are larger than Ceres, which is already an official dwarf planet. So if we’re going to play the game of including dwarf planets in our planetary mnemonic, it’s quickly going to balloon to an unmanageable length. Better not even to try, and just stick with the eight.

So, here’s the takeaway. Dwarf planets are not a sub-classification of planets, but rather, are a completely separate category. There are only 8 planets and 3 current dwarf planets, but as astronomers get around to officially declaring more dwarf planets there will be dozens more. School children will continue learning all 8 planets but they will not learn all the dwarf planets because there are simply too many of them (and unlike studying the eight planets, each of which has many unique features making it worth learning about, most of the dwarf planets will be somewhat similar round iceballs too far out in the solar system for us to get much good information on). So this fourth grader’s mnemnoic, while cute, is destined for the rubbish bin of history. Not that I fault her at all (I blame National Geographic). I commend her for her astronomical precociousness, which puts her above 99.9% of kids her age. It’s just unfortunate that the facts aren’t correct.

5 Responses to “No, Virginia, there are only 8 planets”

  1. Kelly Martin Says:

    I should go pop into the astrology forums I used to hang out in to see what the proposed interpretation for Sedna, Quaoar, Orcus, and 2005 FY9 are. I’m sure the “demotion” of Pluto was a big deal to them, but I admit to not bothering to find out just how they reacted.

    You should have seen them trying to find meaning when Shoemaker-Levy 9 plowed into Jupiter. It’s really quite amusing, in a sad way. You can learn a lot about a person by how they attach meaning to meaningless things. (That is, of course, the real secret of astrology.)

  2. Cyde Weys Says:

    I take it you were frequenting the astrology forums as a skeptic lurker and not as a participant, right? I will admit to reading RedState occasionally, though I don’t comment there anymore (ever since they banned me for not even being particularly liberal, merely for opposing one of their batshit insane conservative viewpoints along the lines of “kill all the brown people crossing the border”).

    The Shoemaker-Levy 9 impact was hardly a meaningless event. In fact, it generated a bonanza of useful scientific data on Jupiter. It was just meaningless in respect to people’s every day lives, like everything else that astrology tries to derive predictions from.

  3. true Says:

    Don’t believe one optimistic word from any public figure about the economy or humanity in general. They are all part of the problem. Its like a game of Monopoly. In America, the richest 1% now hold 1/2 OF ALL UNITED STATES WEALTH. Unlike ‘lesser’ estimates, this includes all stocks, bonds, cash, and material assets held by America’s richest 1%. Even that filthy pig Oprah acknowledged that it was at about 50% in 2006. Naturally, she put her own ‘humanitarian’ spin on it. Calling attention to her own ‘good will’. WHAT A DISGUSTING HYPOCRITE SLOB. THE RICHEST 1% HAVE LITERALLY MADE WORLD PROSPERITY ABSOLUTELY IMPOSSIBLE. Don’t fall for all of their ‘humanitarian’ CRAP. ITS A SHAM. THESE PEOPLE ARE CAUSING THE SAME PROBLEMS THEY PRETEND TO CARE ABOUT. Ask any professor of economics. Money does not grow on trees. The government can’t just print up more on a whim. At any given time, there is a relative limit to the wealth within ANY economy of ANY size. So when too much wealth accumulates at the top, the middle class slip further into debt and the lower class further into poverty. A similar rule applies worldwide. The world’s richest 1% now own over 40% of ALL WORLD WEALTH. This is EVEN AFTER you account for all of this ‘good will’ ‘humanitarian’ BS from celebrities and executives. ITS A SHAM. As they get richer and richer, less wealth is left circulating beneath them. This is the single greatest underlying cause for the current US recession. The middle class can no longer afford to sustain their share of the economy. Their wealth has been gradually transfered to the richest 1%. One way or another, we suffer because of their incredible greed. We are talking about TRILLIONS of dollars. Transfered FROM US TO THEM. Over a period of about 27 years. Thats Reaganomics for you. The wealth does not ‘trickle down’ as we were told it would. It just accumulates at the top. Shrinking the middle class and expanding the lower class. Causing a domino effect of socio-economic problems. But the rich will never stop. They will never settle for a reasonable share of ANYTHING. They will do whatever it takes to get even richer. Leaving even less of the pie for the other 99% of us to share. At the same time, they throw back a few tax deductable crumbs and call themselves ‘humanitarians’. IT CAN’T WORK THIS WAY. This is going to end just like a game of Monopoly. The current US recession will drag on for years and lead into the worst US depression of all time. The richest 1% will live like royalty while the rest of us fight over jobs, food, and gasoline. Crime, poverty, and suicide will skyrocket. So don’t fall for all of this PR CRAP from Hollywood, Pro Sports, and Wall Street PIGS. ITS A SHAM. Remember: They are filthy rich EVEN AFTER their tax deductable contributions. Greedy pigs. Now, we are headed for the worst economic and cultural crisis of all time. SEND A “THANK YOU” NOTE TO YOUR FAVORITE MILLIONAIRE. ITS THEIR FAULT. I’m not discounting other factors like China, sub-prime, or gas prices. But all of those factors combined still pale in comparison to that HUGE transfer of wealth to the rich. Anyway, those other factors are all related and further aggrivated because of GREED. If it weren’t for the OBSCENE distribution of wealth within our country, there never would have been such a market for sub-prime to begin with. Which by the way, was another trick whipped up by greedy bankers and executives. IT MAKES THEM RICHER. The credit industry has been ENDORSED by people like Oprah, Ellen, Dr Phil, and many other celebrities. IT MAKES THEM RICHER. So don’t fall for their ‘good will’ BS. ITS A LIE. If you fall for it, then you’re a fool. If you see any real difference between the moral character of a celebrity, politician, attorney, or executive, then you’re a fool. WAKE UP PEOPLE. The 1% club will always say or do whatever it takes to get as rich as possible. Without the slightest regard for anything or anyone but themselves. Vioxx. Their idea. Sub-prime. Their idea. NAFTA. Their idea. Outsourcing. Their idea. The commercial lobbyist. Their idea. The multi-million dollar lawsuit. Their idea. $200 cell phone bills. Their idea. $200 basketball shoes. Their idea. $30 late fees. Their idea. $30 NSF fees. Their idea. $20 DVDs. Their idea. Subliminal advertising. Their idea. The MASSIVE campaign to turn every American into a brainwashed credit card, pharmaceutical, love-sick, celebrity junkie. Their idea. All of which concentrate the world’s wealth and resources and wreak havok on society. All of which have been CREATED AND ENDORSED by celebrities, athletes, and executives. IT MAKES THEM RICHER. So don’t fall for their ‘ good will’ ‘humanitarian’ BS. ITS A SHAM. NOTHING BUT TAX DEDUCTABLE PR CRAP. Bottom line: The richest 1% will soon tank the largest economy in the world. It will be like nothing we’ve ever seen before. and thats just the beginning. Greed will eventually tank every major economy in the world. Causing millions to suffer and die. Oprah, Angelina, Brad, Bono, and Bill are not part of the solution. They are part of the problem. EXTREME WEALTH HAS MADE WORLD PROSPERITY ABSOLUTELY IMPOSSIBLE. WITHOUT WORLD PROSPERITY, THERE WILL NEVER BE WORLD PEACE OR ANYTHING EVEN CLOSE. GREED KILLS. IT WILL BE OUR DOWNFALL. Of course, the rich will throw a fit and call me a madman. Of course, their ignorant fans will do the same. You have to expect that. But I speak the truth. If you don’t believe me, then copy this entry and run it by any professor of economics or socio-economics. Then tell a friend. Call the local radio station. Re-post this entry or put it in your own words. Be one of the first to predict the worst economic and cultural crisis of all time and explain its cause. WE ARE IN BIG TROUBLE.

  4. Cyde Weys Says:

    I was going to remove the preceding comment as spam, but I don’t think I will. It’s not linking to any website or anything, it’s just sheer hysterical lunacy. I really dig the lack of paragraph breaks.

  5. William (green) Says:

    You could just trim out the middle 95%. That post is… “ooglay”, I believe is the term.