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How Would You Define a Planet?
It doesn't come easy asks: "The argument over the definition of a planet continues. So far, two definitions are favored but without much consensus so far: base the definition of a planet simply on an object's size. Pluto would be near the lower limit and the newly discovered Kuiper Belt objects could also qualify, giving us 10 or 11 planets so far; or define the single dominant body in its immediate neighborhood as the only qualifying object for planetary status. If no one body dominated (such as the millions of individual asteroids in the asteroid belt) then none would qualify for planetary status. In this case Pluto would be disqualified (Neptune would be the dominant body in Pluto's region of space), and the newly discovered Kuiper Belt objects would also fail to qualify. The International Astronomical Union (IAU) working group charged with pinning down the definition of a planet may vote on the proposals within the next two weeks (or they may decide to start all over again with something new). Maybe Slashdot readers can give them some help. How would you define a planet?"
sounds good enough for me ;-)
What could possibly hurt the security of the American people more than giving our own government the ability to hide its
The obvious conditions are round shape and orbits the sun. Size is somewhat subjective although to have a round shape it would have to be above a certain mass.
Oataox or whatever the hell? The guy who came up with that needs to be kicked out of the Astronomy club.
"Ain't no right way to do a wrong thing."
Personally, I think a good definition of a major planet is one that is massive enough that, given its composition, it assumes a sphere-like shape.
cb
Oooh! What does this button do!?
The public will be happy to learn of more planets -- it feels like progress. It'll be hard to convince the public we lost a planet somehow. That sounds like an unimportant consideration, but I don't want us giving the Creationists more ammo for their arguments that Science is fickle. "They used to think there were nine planets, but then they found they were WRONG!"
It's not like any serious science rests on this definition anyway.
--Greg
A nonluminous celestial body larger than an asstroid or cumbucket, illuminated by light from a star, such as Michael Jackson, around which it revolts.
Uncyclopedia: Planet
If it's the size of Marvin's brain, or bigger, it's a Planet.
... well, it's just depressing.
If it's smaller
Wretched, isn't it?
Words like "planet" are meant to "carve nature at its joints". Problems arise when historically there appeared to be joints (planets moved differently than stars in the sky) but, we are learning now that there are no useful joints here. Why bother defining the word planet at all? Is it really that useful to astronomers? And why, say, want Mercury (a small rocky body with no atmospere) to be grouped in a category with Jupiter (a large, mostly gaseous body with an atmosphere) instead of with asteroids (small, rocky bodies with no atmospere)?
I suggested this on www.randi.org a few weeks ago. In Pluto's case have astrologers draw up two parallel charts. One with Pluto as a planet, the other without. After a few weeks we can compare what happened in the world to the astrology charts and that'll settle it.
"The planets don't lie" as I said there. ;)
Trolling is a art,
I would define it thus: An object is a planet if it has enough gravity to form into a sphere but not large enough to ever had fusion start in its interior and has cleared its orbit of debris left over from its formation. This would allow Pluto to remain a planet, as well as "promote" Sedna to planet stus but rule out Ceres.
CDE open sourced! https://sourceforge.net/projects/cdesktopenv/
http://en.wikipedia.org/wiki/Definition_of_Planet
The problem with disqualifying Pluto because of Neptune being the more dominant body falls apart when you consider the eccentric orbit of Pluto and just how far that takes it from Neptune's "region of space".
What exactly is the definition of a region of space?
How much larger must an object be than its neighbors in order to be considered the dominant object of its neighbors? Twice as large? Four times?
wouldn't stars be "planets" as well?
If you can land on it and score with an alien chick, it's a planet.
...the mice?
If you could reason with religious people, there would be no religious people
I think we should just drop the name. It can still exist, but not in a scientific context. We just go with MVEMJSUNP as "planets" and make up words with given definitions before we start trying to apply them them to things.
BOOS: Big Objects Orbiting Star.
BOOBOOS: Big Objects Orbiting Big Objects Orbiting Star.
LOOS: Little Objects Orbiting Star.
FOSC: Floating Outer Space Crap.
Planet: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto.
Oh, and since I know you'll ask the difference between a BOOS and a LOOS is that a BOOS is large enough that it's own gravity keeps it roughly spherical.
It is no longer uncommon to be uncommon.
therefore, mercury would NOT be a planet (more like a moon of the sun)
and titan, even though it orbits saturn, WOULD be a planet
i think that makes most the most sense: what an object orbits shouldn't matter, it's composition should be the largest consideration
some other nomenclature can address what it orbits ("a moon of the sun" or "a planet of saturn")
it should be considered either
REGARDLESS of what it orbits
intellectual property law is philosophically incoherent. it is your moral duty to ignore it or sabotage it
When borderline cases arise, concepts proliferate.
Apart from the Platonists in the audience, intelligent people realize that concepts are made things, artefacts created by humans to facilitate certain types of interaction with the world. Now, the world is a particular way, and that puts constraints on the sorts of concepts that are useful to us, but it doesn't determine a single set of concepts that will do the job. Therefore, concepts vary from person to person, and one person's pornography is another person's erotica, and so on.
Concepts, like all tools, are judged to be better or worse according to use. Some of the uses of "planet" are political--every astronomer monkey wants to be the discoverer of a "plant", because that will attract and impress other monkeys of the complementary sexual orientation. This is just part of our hertiage as monkey's, and we may as well admit it. Other uses are scientific--planetologists already divide planets into sub-categories like "gas giant" and "terrestrial planet", because quite different physical processes dominate these bodies, and distinguishing them allows us to focus our attention more fully on one set of processes or the other. For beings of definitely limited brain power, this is extremely useful.
Historically the term "planet" mixed several completely unrelated things: size, distance from Earth, and being in orbit around the Sun. Planets were "wandering stars", and it just happens that the only things that fell into that category were large bodies far from Earth that orbited the Sun. Things like the Moon, which is close, wasn't a planet because it had a visible disk, which stars do not. But this is entirely accidental--if one of the inner planets had had a moon visible from Earth with the naked eye it is likely that the concept of planet would already be more various than it already is.
I think it better to create a bunch of new terms that acknowledge the rich division of bodies we can now see, rather than get hung up on the historical term "planet". The things we care about include at least three axes: size, composition and orbit. Trying to assign a single word to a particular region of a three-dimensional space (which probably isn't even simply connected!) is a silly waste of time, driven purely by monkey psychology, and has no scientific value. In fact, it may even have negative consequences for science, because getting hung up on historical terms may also help keep people hung up on historical concepts.
So my vote would be to expunge the term "planet" from the astronomical lexicon entirely. It's the only way to be sure.
Blasphemy is a human right. Blasphemophobia kills.
I think you missed a really important one:
/ducks
Big Objects Orbiting Binary Stars...
the above is my personal opinion and does not necessarily reflect that of the little voices in my head
The only way to define it is obvious:
Anything you can blow up with the Death Star!
"City hall" in German is "Rathaus" Kinda explains a few things......
What the heck do they teach kids these days?
Saturn and Uranus were titans - beings that came before the gods. Neptune was named in modern times, but they kept the roman naming tradition, same with Pluto, Roman god of the dead.
And then they proceeded to waste all the other greek and roman names on every rock, brick and crater they could find which is why we're reduced to naming moons after Shakespearean characters.
The naming of Charon was a slick trick - the discoverer specified that the name be spelled like the name of the mythical figure, but that the name be pronounced "Sharon" - which happened to be the guys wife.
Clear, Dark Skies
Then you have to define "belt" - if you look atthe relative distances of things the object in the kuiper "belt" are more spread out that say the objects (read planets) in the inner solar system of roughly similar size.
Personally I think it is silly to disqualify something because it has "neighbors" or orbits in a "belt".
My $.02:
Any object that revolves around a star, and is not a star, has enough mass to be roughly spherical (say +/- 1% of a perfect sphere) due to its gravity is a PLANET.
Objects that are roughly spherical that revolve around planets are MOONS (regardless of size.) If two objects revolve around each other and their center of gravity lies outside the radius of either partner then it is a binary planet.
Objects that revolve around a star that are not roughly spherical are MINOR OBJECTS. This leads us to a bit of a problem because under my definition there would be no distinction between our friends the comets and asteroids.
I imagine there could be a further classification, based on the shape of the orbit - so we can continue to have "comets" and "asteroids". However I do not like using the orbit shape in any definition.
Objects that revolve around a planet taht are not roughly spherical are SATELLITES.
By the way the reason WHY i do not like using the shape of the orbit or something like the vicinity of other objects in the definition is simple. Those characteristics can be changed. Orbits gradually change over time, especially early in the life cycle of the solar system.
Granted objects are "captured" by planets and stars, and "ejected" in the same way. However, given enough time (and any external influences) don't orbits tend to become circular? So just because comets have highly elliptical orbits now does not mean they will be elliptical forever. The orbital shape is a TRANSITION characteristic. It is not inherent to the object.
Oh well I have rambled on way to long about this....I am ponderig the much larger question - "Why do I care?"