Definition of Planet to be Announced in September

MasaMuneCyrus writes "After over seven years of debating, the International Astronomical Union announced that it expects to announce the official definition of a planet in September. After many-a-deadlock, they handed the task of deciding exactly what a planet is to a new committee, which includes historians and educators. 'They wanted a different perspective from that of planetary scientists,' said Edward Bowell, an astronomer at Lowell Observatory who is also vice president of the IAU's Division III-Planetary Systems Sciences group. If all goes according to plan, the wording will be proposed in their 12-day General Assembly meeting in Prague."

Comments

Any definition is arbitrary

[Frans Faase]

As there are so many parameters that a celestrical body can have, any definition of what is a planet and what is not, is highly arbitrary and thus unscientific and based on emotional considerations. And because of this, there will always be large groups of people who will reject any such definition. Especially, because it will all be wheter Pluto should be called a planet or not.

I think the most logical thing would be to consider "planet" a part of the name of a celestrical body, just like we do with "ocean" and "sea", and not use it as a classification word.

Re:Any definition is arbitrary

[Grismar]

I'd agree that there are non-arbitry ways to create a definition and then attach the name 'planet' to it. But you have to ask yourself why you would be doing this. Similar as with the 'ocean and sea' example, what exactly is the point of calling something a planet in the first place?

This is not to say that calling anything anything is pointless. But it is pointless to invent a named category of objects if that category serves no other purpose than a placeholder for the name.

It would seem that in the case of oceans and seas the point is that oceans connect to multiple other large bodies of water, whereas seas are less connected. I can see how that makes sense from a geological point of view, even though IANAG.

From a scientific point of view, naming a clearly defined category, with non-arbitrary criteria, only makes sense if you want to use that name to refer to the category to state or prove something about it. Frankly, I don't really see such a use for the word 'planet', at least not as it stands.

Re:Tangible?

[Shrithe]

You seem to have a fundamental misunderstanding of the nature of proof in science. We've observed those planets about as well as we've observed many subatomic particles. Entities are posited to fit the observation. This is the case in any area of science. Not counting possible margins of error in measurements, we've observed these planets in much the same way as we observe subatomic particles. Would you like to stop believing in those?

If you would, would mind explaining exactly how all our predictions based on those particles ended up being right? Lucky guesses, the lot of them?

That's an awfully big leap of faith.

Your comparison, by the way, entirely fails to hold water. The issue here is a historical mistake having been entrenched in the popular definition, and the lack of a technical definition. IUPAC doesn't have to deal with popular definitions confusing the issue, they're already developed technical definitions for anything within their scope.

Re:Tangible?

[Graymalkin]

This sentiment is baffling to me. You're living on a big hunk of emperical evidence. If the planets of our solar system can form it follows logically that planets can form around other stars. If our solar system is like even a small fraction of other solar systems we can use information about ours to look for other ones. There's several methods to find extrasolar planets, and quite often multiple methods can be used on the same system to verify the findings of other observations. Large planets cause a star to appear to wobble. This happens because the two bodies are orbiting their mutual barycenter. By keeping track of a star's periodic doppler shift it is possible to determine the mass of an orbiting planet or planets. This method can also be used to confirm findings from planetary transit observations. When a planet's orbit brings it between its parent star and us the light of the star will dim slightly and for a period of time related to the size of the planet and length of its orbital period. With this information the mass of the planet can be determined. If this meshes with the star's wobble you've got pretty good evidence of a planet orbiting that star.

Pluto wins hands-down because...

[waynemcdougall]

it's the only planet (in our solar system) discovered by an American.

Therefore whatever definition is used, Pluto will always be included as a planet.

Same reason why American's will always keep the penny. Ego and historical pride.

Re:In October...

[paul248]

Wow, I'd never looked at debial-legal before, so I went there and the first thing I saw was people arguing over whether the GPL itself violates the Debian Free Software Guidelines...

Your comment is starting to make perfect sense.

Re:I love western thinking

[TheAntiCrust]

Yes. Everything must have a category. Nature doesn't create categories becuase it doesn't seem to need to understand itself. As humans, we need to format data about the world in ways we can understand. Categorization is part of this.

You can let things be all you want, I'd prefer striving to make things better.

Missing the Point?

[TMA1]

I understand why there's an effort to define what a planet is. For one thing, it's important for common usage. It helps fill in the blanks on headlines such as, Scientists Observed the Star ______ has a _________ . However, our solar system is easiest to understand if you realize it's composed of the following.

• Four terrestrial planets
• Four jovian planets
• The Kuiper Belt objects
• and the remaining comets, asteroids, dust, etc.

(Yes, I know I'm using the word planet, but the actual dispute is being driven by the discovery of a Kuiper belt object larger than Pluto and farther from the Sun).

Re:terrestrial, jovian, cometary

[WalksOnDirt]

We currently have three types of planets based on material:

Earth like, 4 samples
Jupiter like, 4 samples
Pluto like, 2 samples (including Xena)

Why the push to go from three types back down to two? Sheesh, the gas giants are so much larger than the rocky planets maybe only those should be called planets. Reclassifying Pluto as a large "Kuiper belt object" makes little more sense that making Earth a large "Close orbiting asteroid".