The Status of Pluto

[mabfan]

New Scientist is reporting the discovery of a Trans-Neptunian Object that might be twice as large as Pluto.

If the discovery is confirmed, this is probably going to reopen the debate of whether Pluto should still be considered a planet. A few years ago, The Rose Center for Earth and Space generated a lot of controversy when one of their permanent exhibits only listed eight planets in the solar system. Enough people asked about Pluto that they added a plaque explaining why they had not included it. The Center's director, Neil deGrasse Tyson, wrote an essay called Pluto's Honor (1999) in which he explained Pluto's demotion. Tyson noted the following:

As citizen Tyson, I feel compelled to defend Pluto's honor. It lives deeply in our twentieth-century culture and consciousness and somehow rounds out the diversity of our family of planets like the troubled sibling of a large family. Nearly every school child thinks of Pluto as an old friend. And there was always something poetic about being number nine.

As professor Tyson, however, I must vote--with a heavy heart--for demotion. Pluto was always an enigma to teach. But I'd bet Pluto is happy now. It went from being the runt of the planets to the undisputed King of the Kuiper belt. Pluto is now the "big man" on a celestial campus that occupies a larger tract of the (outer) solar system than that spanned by the eight planets.

Where do I stand on this? More with sentiment, I'm afraid. I've used Pluto's bizarre status as a teaching tool, but even so, I grew up with the notion ingrained in me that there were nine planets. I still remember the mnemonic I learned in fourth grade to remember their order: My Very Earnest Mother Just Served Us Nine Pickles. (Of course, at the time, Pluto's orbit had brought it closer to the Sun than Neptune, but let us not quibble.) I would hate to see Pluto reduced to simply one of a new class of smaller objects.

But...if astronomers start to find other TNOs larger than Pluto, I guess I'm going to have to change my mind. So, in some way, I'm rooting for this discovery to either be unique or a mistake. We'll see what happens.

Comments

[sdelmonte]

I don't see any reason why these so-called TNOs can't be called planets as well. Let's just see that a planet is something of a certain size or larger that orbits the Wun. And Pluto is the minimum size. Why must it be made more complicated than that?

I am still annoyed that Tyson took it upon himself to exclude Pluto from the order of the planets at the new Rose Center. He is entitled to an opinion, but his deicision to mke that opinion the "law" of the planetarium strikes me as a bit arrogant. Then again, the AMNH is busy redefining dinosaurs in its new exhibition, so maybe it's normal for science museums to do that.

[mabfan.livejournal.com]

The problem with calling the TNOs planets is that at some point you'll find an object that is on the borderline again, and then what do you do?

I wouldn't call Tyson's behavior arrogant; I've met him, and he is a delightfully charming gentleman. But I do think he was honestly surprised by the controversy when they left Pluto out of the list of planets, and it might have been better to put up an explanatory plaque at the beginning.

[dianora2.livejournal.com]

My Very Earnest Mother Just Served Us Nachos?

[mabfan.livejournal.com]

Ha! But what were we to do from the 1970s to 1999 when Pluto was closer? My Very Earnest Mother Just Served Us People Nachos?

[kuroshii.livejournal.com]

how about Parmesan Noodles! :)

(it's my favorite comfort food on this planet, anyway)

[gnomi.livejournal.com]

Poor Pluto. Second in status to the other planets and second in status to Goofy.

:-)

[mabfan.livejournal.com]

Ha. Ha, ha, ha.

[stevethorn.livejournal.com]

I think the worst part is that if Pluto is no longer a planet, then Charon probably cannot be its moon. And Charon as a name for a moon (or planet, for that matter) is just extremely cool.

[mabfan.livejournal.com]

Even before the controversy, astronomers often referred to the Pluto-Charon system, since Charon was so close in mass and size to Pluto compared to the moons of other planets. So even if Pluto loses its status as a planet, I doubt Pluto and Charon will lose their names.

[zsero.livejournal.com]

Now they're saying it's only 70% of Pluto's diameter, which I suppose is good for those who are emotionally attached to the idea of 9 planets, since they still have some basis for continuing to call Pluto a planet. All the have to do is draw the line at 2390 km (or, so as not to be completely transparent, at 2000 km), and say that anything above that counts as a planet, and anything below it doesn't. Until the next really big plutino shows up.

Ceres was a planet, for a short while, until it was discovered that it was but one of many asteroids, and it counted as a planet then so would many of the others. So it was dropped from the roster. Now the same thing is happening to Pluto, and I don't see why it should get better treatment than Ceres, just because it was a planet long enough to get into the encyclopaedias and textbooks.

If this new object had turned out to be bigger than Pluto, then I'd say that was the last straw, and it would be impossible for anyone to keep a straight face while calling Pluto a planet. As it is, it remains possible, if barely.

[kuroshii.livejournal.com]

they've gone back to saying it's bigger than pluto. :( and they're almost sure it's a planet...

http://www.jpl.nasa.gov/news/news.cfm?release=2005-126

[crackboy.livejournal.com]

From the ever-relevant Brunching archives (http://www.brunching.com/)...

A Brief Conversation with the Planet Pluto (http://www.brunching.com/conversationpluto.html) and Another Brief Conversation with the Planet Pluto (http://www.brunching.com/morepluto.html).

"BS: I see. Let's talk about your moon, Charon.

P: What about it?

BS: Well it's awfully big, compared to you.

P: Again with the size thing! What is it with you people and size?"

"BS: You have life?

P: Sure. Life. Plants. Strip malls. Whatever. Like you care. Prove me wrong."

He seems to have a bit of a chip on his shoulder.

[marthag8.livejournal.com]

Of course, you can't discuss the Pluto controversy without mentioning the very excellent song about it, Planet X by Christine Lavin.

[mabfan.livejournal.com]

Cool song. Thanks for the link.

[fynixsoul.livejournal.com]

At my daycare center, we just finished "Space Week" with the five year olds. They had trouble with the idea that Pluto and Neptune change places. I can only imagine the looks on their faces if I tried to explain that Pluto is not in fact a planet after all...but there might still be another planet out there (can we call this new thing a planet? I heard somewhere a celestial body has to have a molten center to be a planet, is this true? Does Pluto?) that we justdiscovered and don't yet have a name for...

and as long as i've stolen your attention for the moment, is the asteroid belt between earth and mars or mars and jupiter? or somewhere else entirely?

[mabfan.livejournal.com]

The asteroid belt is between Mars and Jupiter.

I've never heard of the "molten center" definition of a planet. Maybe for a tootsie roll lollilop? :-)