Silly Pluto Food Fights Continue
A new definition would add 102 planets to our solar system — including Pluto, Washington Post
“[Alan Stern] scoffed at Pluto’s new classification, “dwarf planet” — “How can an adjective in front of a noun not describe the noun?” Stern asked. “There are dwarf stars but they’re still considered stars…”
... “The paper that [Kirby Runyon will present this week isn’t a formal proposal, like the one that was devised at the IAU. He’s not putting his definition up to a vote, or even suggesting that it should replace the IAUs. If he did, it’s unlikely that the IAU would adopt it. [Carolyn] Porco, who is one of the lead scientists for NASA’s Cassini mission to Saturn, pointed out that she is a planetary scientist and has no problem with the IAU’s orbital dynamics-based definition. She also noted that astronomers already have a perfectly serviceable term for the kind of body Stern and Runyon are trying to describe: “world.” In her view, the only scientists who want to make those places planets are people who study Pluto.”
Keith’s note: What is Stern’s point? he says “There are dwarf stars but they’re still considered stars”. OK, by his logic a “dwarf planet” is therefore still considered a “planet”. Hooray: Pluto is a planet. So why does Stern continue to moan and groan about whether or not Pluto is a planet? Stern and his small cadre of Pluto loyalists complain incessantly about the 2006 IAU vote to reclassify Pluto – yet in the ensuing decade no one has seen fit to try and formally submit a better definition to the IAU and have a discussion that involves the entire space science community. They’d rather just complain, it would seem, since that attracts more attention – to Pluto.
I’m in agreement. Who cares if we call Pluto a “dwarf planet” or “minor planet”? It pretty clearly is distinct from the other eight major planets in both size and orbit.
And not “the last planet” but really the innermost representative of a distinct category of objects at the rim of the solar system.
Let’s define Pluto as a Classic Planet (there are eight others). Any others (standard, dwarf, transient, etc) are merely planets.
BTW, let’s not forget the Antiquity Planets: Me, V, Ma, J, S. Earth isn’t included since it was just ‘the Earth’ back then.
I do have problems with the dynamical definitions put forward by the IAU since by them Jupiter doesn’t count (re: the Trojan asteroids) but I must admit I have not looked into submitting a proposal. Do you have to be a member?
I interacted briefly with one of the self-appointed “Official Pluto Defenders” on twitter and the irrational attitude was startling.
One thing I never see brought up is that this is NOT unprecedented. Ceres was discovered, declared to be a planet, given a classical planetary symbol, and then demoted. I believe at least one other asteroid had a similar experience.
Asteroid discovered then we find we have an asteroid belt. Pluto discovered then we find we have a Kuiper belt. Seems very similar.
Somehow the 19th century schoolchildren survived the trauma. Ceres survived, and is still a very cool object. The asteroids are all still there and don’t care what we call them.
Perhaps if Ceres had a Disney cartoon character named for it that would make the difference… but I don’t understand why even defenders of the (sensible) change never point out that this very thing has happened before and it’s PART OF THE PROCESS.
If you’re unwilling to change your understanding and possibly classification of things as we inevitably learn more about them – then you AREN’T A SCIENTIST. You’re a publicist.
You’re point that the asteroids don’t care what we call them is the salable point here. No one in this discussion is “right” or “wrong” about a label as long as we can’t decide on why a label. When I used to go on Galaxy Zoo, the scientists needed me to separate out the various shape types so that focus could be applied for specific research purposes. Also, they needed the crowd to keep an eye out for gravity lensing because it was and probably still is rather important. Planetary science is the same way.
That is the problem with terms that folks cling to for historical rather than technical reasons. Going to a simple definition of planets, larger enough to be nearly round from gravity and orbiting the Sun, means that instead of being rare and wonderful Celestial Bodies they become common, which requires a paradigm shift from the historical view of planets most planetary scientists are not able to make.
It should also be noted that thanks to the age of spacecraft exploring the Solar System the same issue now applies to moons. You have the moons big enough to be nearly round from the pull of gravity and then you have the hundreds of oversized boulders also called moons. Should they be? Should a ten meter diameter rock be called a moon if it orbits a planet? Or should they have another name?
Should Jupiter really be considered to have 4 moons and a cloud of dozens of dwarf moons? Or just dozens of moons.
And then you have the two odd ball objects. Earth’s Moon and Charon that have the characteristics more of double-planets than traditional planets (or is Pluto-Charon a double dwarf planet?).
But really, if you are not going to discriminate between different types of moons it is inconsistent to discriminate between different sizes of planets.
And then what is the real difference between a comet and asteroid now that we suspect many asteroids are just former comets with their violates gone? And the discovery that even large asteroids like Ceres have a lot of water under their surface like a dirty snowball. One could well imagined in the distant pass it had a comet like tail as the surface ice boiled off in the heat of the early Sun. Or would it have never had surface ice? But if not than that would seem stranger than if it did.
Really given the discoveries being made about other Solar Systems and our own their really needs to be a wholesale redefinition of terms.
For what it’s worth, a common, internal usage on the Cassini project is to call any moon under 100 km in radius a “rock.” But only if it’s big enough to be resolved.
I think what I read somewhere is that something has to have a certain mass before its tidal forces shape it into a rough sphere. Perhaps that should mark off a category for separation among objects and thus maybe denote a “rock” from other stuff like “planetoid”.
Yes, that would be one dividing line. But a nomenclature is really needed for organizing all of the objects being discovered into categories that help theories emerge. It appears solar systems are still waiting for their Carl Linnaeus.
Indeed Star Trek has already anticipated this 🙂
http://www.sttff.net/planet…
Hmm…not detailed enough though. You’re correct though in the point that once we can see terrestrial exo-planets we will see patterns immerge that we can categorize on…perhaps with greater specificity. What we see now by looking at the Sol system is that each planet is such a wonderfully unique world so as to make scientifically useful categories almost boring. “Terrestrial” vs “Gas Giant”, “Goldilocks zone”, which if I recall correctly actually includes Mars and Venus which makes it a bit deceptive. I’m far from an expert so there might already be better designators that I’m missing.
It’s the object’s gravity, combined with its internal structure which makes it round. This is part of the current IAU definition of a planet. They also require that a planet orbit the Sun, not another body (interesting for Pluto, if you call the Pluto-Charon system a binary) and that it has enough gravity to clear the orbital space around it of other objects (which is a bit vague, but something Pluto doesn’t do.)
As far as roundness goes, a somewhat embarrassing fact is that a key parameter was named after the person who came up with it. The Love number, after Augustus Love, describes how easily a body can be deformed by gravity. So something which is stiff and rigid has a high Love number, while something which is soft and flexible has a low Love number. That’s occasionally led to some bad jokes​.
I can imagine.
So we’re going to need to make sure those who name the planetoids themselves are very, very careful about it, or this detail could get overly distracting in a hurry.
Tell me, does the planetoid’s age have anything to do with it?
I thought that technically it is a satellite not a moon?
“Moon” and “natural satellite” are used more-or-less interchangeably, and “natural” is typically left off when that part is obvious. The only preference I’ve noticed is stylistic. Nobody talks about a flyby of a natural satellite by an artificial satellite. That would just be confusing and awkward phrasing. I’m not aware of any official preference for “satellite” over “moon.”
Nature has no labels, and few borders. It is us humans who need to draw circles around things and categorize them based on various characteristics to help us learn. Pluto as a planet is simple…but not so simple. It certainly doesn’t “behave” like the Main 8. So the question to ask is, “What purpose does the name “Planet” really serve?” If we started assigning Latin taxonomic family names to solar system objects like we do in Biology, where would that take us with Pluto?
I like Pluto too, a lot, but as an occasional teacher I think things should be grouped for learning ease.
The difference in your legacy project? You visited the last planet in the solar system to visiting one of the many dwarf planets?
it is all about the listing in the history books and what will be remembered?