It’s almost official now: Pluto really is a planet. As Phil points out, though, this means there are now 12 planets, with maybe many more to come.
Pharyngula
Evolution, development, and random biological ejaculations from a godless liberal
It’s almost official now: Pluto really is a planet. As Phil points out, though, this means there are now 12 planets, with maybe many more to come.
Arrrrrrgh! This means every little pipsqueak planetoid and asteroid is going to get added to the list. All to save “poor, little” Pluto.
As Nero Wolfe would say, “Bah!”.
How to make our solar system to have 1000+ planets : Take a bottle of mercury and spray it somewhere outside of earth’s gravity well – it will form small spherical droplets, which, because they orbit the sun and assume spherical shape on their own should count as planets too… Or, at least according that silly definition.
Interesting. And I see a lot of parallels between the arguments about what is a planet and the arguments about what is a baby – e.g. “For one thing, if a planet the size of, say, Saturn, gets ejected from a solar system — a scenario that can happen early in the life of a forming system — then under Rule 1 it wouldn’t be a planet. That’s silly. Why should location matter?” I completely agree. Location shouldn’t matter.
Obviously this means we need a new mnemonic to replace “My very educated mother just sent us nine pizzas”
How about:”My very educated mother causually just sent us nine cheese pizzas undercover?”
Fortunately the Linnean mnemonic “Kraft Parmesan cheese on fingers gets sticky” is still valid. Those Phylocode punks can get the Linnean ranks when they pry them from my cold, dead hands.
Jason, was that a reference to the argument by the anti-abortion crowd, that the only difference between a fetus and a baby is location? If so, here is a newsflash: birth is a biologically significant process. Among other things, it is only once the new baby starts breathing that it develops normal blood oxygen levels. This has an affect on the new baby’s brain and consciousness that will never occur in utero. Respiration also starts a series of other physiological changes. One can argue over the importance of these changes. But only someone ignorant of biology would assert that birth is nothing but a change of location. Not that facts are relevant to most anti-abortion arguments.
I betcha the astrology industry will find a way to make a profit on any new revisions that happen.
Idiot! You’ve fallen for the troll’s trap: now that you’ve responded to his inane posts, he’s now part of this thread’s discussion. If we’d just ignored him, the post would just be there, sterile – now it’s actively metastasizing.
Oops. Sorry.
As noted on the Bad Astronomers blog, since Pluto and Charon are twin planets orbiting each other the P and C in the menmonic will have to change places accordingly. And not to mention the fact that Pluto (and of course also Charon) sometimes are closer to the Sun than Neptune. I suggest we have four different mnemonics and an official calendar stating which mnemonic to use at the apropriate time.
Who needs mnemonics? I actually have to recite the names of the PLANETS to remember the thing about the pizza. (Although I do rely on “Killer penguins come over for group sex” on the rare occasion that I need to remember if Order is higher than Class.)
I’m thrilled about the sphericalness criterion, as it’s the only one I’ve ever heard that is non-arbitraty and makes sense. (As for the drops-of-mercury comment, it has to be spherical by virtue of its GRAVITY, not surface tension.) But the can of worms it opens up in terms of trans-Neptunian objects… we can expect 50 planets by 2020, folks.
Does that mean my great big ball of string doesn’t count?
“Location shouldn’t matter.”
So are some of Jupiter’s moon planets because they are big enough? I think BEHAVIOR is what matters, not size or location.
I would define a planet as a “spherical object with a regular orbit around a star and enough gravity to have an atmosphere.”
at room temperature, you would need to have a mercury ball of ~10m diameter to have it hold together more by gravity than surface tension. However this is only a minor problem – just place the mercury droplet close to sun to heat it just below the boiling point. The surface tension will decrease dramatically, so gravitational forces will exceed surface tension forces even for a 1cm droplet…
Phil’s spam filter keeps catching all my comments, for some reason, so I’ll post this here as well as over there.
One simple question: Why does noone object to lumping both Mercury and Jupiter into the same category of “planet”? Why, then, if we can make that work, are Pluto and Ceres so objectionable? Surely, Mercury and Ceres or Mercury and Pluto have more in common than Mercury and Jupiter.
I’d be all in favour of creating more granularity in the system, which is why I like the IAU’s new definition. It extends the term planet to a lot of new object while recognising that there are significant and clear categories within the broader definition (“dwarf planets” and “plutons”). Honestly, I think they should have gone farther and defined similar distinct categories for rocky planets and gas giants, although obviously those categories are rather well-established by tradition.
T_U_T: I think you’d find the mercury would boil off or freeze, not stay as a liquid. (Or would the solid form a ball too?)
Yes, it would slowly evaporate, and thus cease to be …ehm… ‘planet’, after a couple of days, but before that, it would still count as a ‘planet’.
My biggest problem with Pluto is the orbit. Not even close to circular, not in plane with the rest of the planets, and centred not even close to on the Sun. That and the icy rocky composition.
It feels more like a blob of leftovers than an actual planet to me.
These threads demonstrate well why the suggested definition is made by committee instead of driven by research. :-)
“Who needs mnemonics? I actually have to recite the names of the PLANETS to remember the thing about the pizza.”
Same here. The day it will be easier to remember a memnonic, I will use it. That doesn’t seem to happen.
“Yes, it would slowly evaporate, and thus cease to be …ehm… ‘planet’, after a couple of days, but before that, it would still count as a ‘planet’.”
Yes, as Phil and commenters show the definition is contingent. (But so is the ordering of planets.) It also lacks good definitions, like on “large eccentricities”.
But it does some things. Planets are welldefined for the first time. No former planets are thrown out which placates the public. Planethunters will have added incentive. And plutons have likely another formation story than the inner planets. Not too bad for a committee work.
There are only four planets — Jupiter, Saturn, Uranus, and Neptune. Everything else is rubble.
>No former planets are thrown out which placates the public.
Lets me clear about this, people. Pluto is not a planet and never will be. The definition has been stretched ad absurdum as a sop to Americans who don’t want to forfeit the only planet discovered by an American. By the new definition, our own moon and many of the Jovian and Saturnian satellites should also be included.
Unscientific navel-gazing.
If Pluto-Charon is a double-planet, explain again–slowly why Earth-Moon isn’t.
And, while we’re at it, why not Quaoar, or Sedna?
Now, I get the part about how Ceres qualifies, but how Pallas and Juno don’t.
I do have a problem with “planetizing” Charon, but leaving Moon, Io, Europa, Ganymede, Callisto, Titan, and Triton as satellites (not to mention other satellites of Saturn and Uranus which are larger than Charon, let alone the asteroids–and yes, I understand that Ganymede, Titan, and Triton are Mercury-sized).
But in the final analysis, it’s all moot. I think much of the controversy stems from curriculum sticklers who want things to fit neatly into memorizable lists of facts.
This will, however, make for a host of fun science questions when we get around to writing science questions for the 2006-07 Kansas Scholars’ Bowl season!
Yeah, I’ve been thinking about this all day.
I think that this means it’s easier to get into the family of “planets” than it is to join the European Economic Union. Were I Turkey, I might think of having myself declared a planet as part of the campaign to get into the EEU. I mean, would the other nations blackball a new planet?
It also means that there is a greater liklihood that intelligent design can be declared a planet than that it will ever make a contribution to science in biology. I mean, it’s dense enough already, and with that expanding head, soon it will be big enough. ID can make the mark in astronomy that it never could in biology.
I gotta go.
Well, they couldn’t very well kick out Pluto and keep Mercury. If you think the standard they have looks arcane, wait till you see what you’d need to do that…
Actually, my first reaction was “Asimov, thou shouldst be living at this hour.” He once wrote an essay called _Double Planet_ on the Earth-Moon system, then recanted once Pluto-Charon was discovered, saying *that* deserved the title much more. Too bad he isn’t around to enjoy this.
The Moon doesn’t qualify because it orbits Earth and the center of mass of the Earth-Moon system is inside the Earth. However, as Phil points out, this is a temporary feature and eventually the Moon will recede far enough to put the center of mass *outside* the Earth – at that point Earth-Moon will officially be a double planet like Pluto-Charon, assuming the standards haven’t been edited again and anyone is still around to care. The Galileans, Titan etc. aren’t planets for the same reason, except that since their primaries are so much more massive and bigger, I don’t see the centers of mass moving outside the gas giants any time soon.
It’s arbitrary, but any standard is going to be arbitrary. I don’t think throwing out small rockballs like Mercury, Ceres and Pluto would necessarily be any better than throwing them in. I’m a bit surprised about Charon, but again, they have to draw the line somewhere and the surface of the more massive body is as good a place as any. We may eventually find rather a lot of small distant planets of which Pluto is only the best-known (and I think closest), but so what? They’re there whether we call them planets or call them something else.
Ultimately, though, we still have four gas giants, three medium sized rockballs, a bunch of smaller rock or ice balls and lots of even smaller irregularly-shaped objects (and of course, Bertrand Russell’s teapot). The actual objects are still out there and haven’t been affected a bit (take that, postmodernists!).
>Well, they couldn’t very well kick out Pluto and keep Mercury
Why ever not? Mercury’s diameter is more than twice that of Pluto, and not far off that of Mars.
Garrett: Where is the sun-Pluto center of mass? Is it not in the sun somewhere?
Planet by Fiat? The Italians made Pluto?
Lycaenops:
“Pluto is not a planet and never will be.”
It has been so defined. AFAIK it isn’t terribly important to define them either way, if planetary system modelling gives a larger range of bodies.
“The definition has been stretched ad absurdum as a sop to Americans who don’t want to forfeit the only planet discovered by an American.”
I think ordinary people are used to todays planets and oppose change. But yes, that didn’t help the change.
“By the new definition, our own moon and many of the Jovian and Saturnian satellites should also be included.”
No. The masscenter definition excludes objects behaving like moons, while capturing objects behaving as double planets.
http://onegoodmove.org/1gm/1gmarchive/2006/08/pluto.html
Welcome the dwarves… Ceres and Lesbian! Ooops. I mean Xena.