Nine Planets Become 12 with Controversial New Definition

[kevin]

What would you say if they found a world as big as Mercury out there? Or maybe as big as Mars. This makes no sense.

Que?

[Aslkahuna]

Should be noted that this proposal has not yet been voted on so it's not final. Ceres is included because it's known to be round whereas the other asteroids are not. Nix and Hydra are to small to ever become round so they are moons. Charon is large enough to be round and, in fact, is the largest body in orbit or mutual orbit around another body in terms of mass ratio (which is why the center of mass of the system is located between the two objects). By the time the Moon is far enough out for the barycenter of our system to lie outside the Earth's surface, the Sun will have evolved to the point where we won't be around to care anyway.

Steve

[WmE]

There's even a theory that a body as large as Neptune exists near the Oort cloud and every time it crosses it (about all 65 million years) some astroids are forced in the inner solar system.

I'm not sure if this is 100% correct, but it's something like that.

[kevin]

I like the idea of the objects being known as plutons. Now, we can still call the eight planets 'classical planets' which would make sense, since we are entering a new domain of planetary astronomy.

There being an arbitrary size limit to planets beyond the condition of being spherical seems strange. Afterall why if we don't include icy planet sized objects that orbit the sun, should we call Earth and Jupiter the same thing. I'd say there are as many differences between the solid planets and the gas planets as between the solid + gas and the 'planets' beyond Neptune.

[Audrey2Katrina]

There's even a theory that a body as large as Neptune exists near the Oort cloud and every time it crosses it (about all 65 million years) some astroids are forced in the inner solar system.

I'm not sure if this is 100% correct, but it's something like that.

What I've heard about this "alleged" object is that it was a "dark twin" of our own sun, and that it's movement every 65 million years or so, causes enough perturbations in the Oort Cloud to send in a rain of objects, some of which have precipitated mass extinctions on Earth. Not certain; but I believe it's called the "Nemesis" theory, and the dark twin given that very name. Pure conjecture, however, and little more.

A2K

[Audrey2Katrina]

There being an arbitrary size limit to planets beyond the condition of being spherical seems strange. Afterall why if we don't include icy planet sized objects that orbit the sun, should we call Earth and Jupiter the same thing. I'd say there are as many differences between the solid planets and the gas planets as between the solid + gas and the 'planets' beyond Neptune.

That is a valid point. Traditionally, you've had the "rocks" called terrestrials, and the gas giants... well, gas giants; and yes they are quite different. I agree with you on the requirement that it be spherical as opposed to possibly larger objects that just haven't accreted to the nice pretty looking orb being excluded from the club. Perhaps there is a middle-ground that will have to be reached, as this so-called new classification system lends itself to a lot of arbitrary, and consequently heated disputations about just what this or that is--or will ever be.

My mention of the Earth moon system also was not to contend the mass-distance ratio; it just seems downright silly to call one object that is unquestionably in mutual orbit with another a planet, and another a "moon" based on the location of that barycenter being in a region between the two as opposed to being somewhat within one body or the other--the fact remains that both are unquestionably in mutual free-fall dances. I would really like to know the barycenter between Saturn and some of its farthest moons--because you have to go pretty far down into that sucker to hit anything solid, with a density less than that of water. So I suppose if the barycenter is in the atmosphere that doesn't count? Seriously I think this idea has major flaws--and while it's nice all this discussion about the possibilities and probabilities, I hope more sensible mentalities prevail and some sort of reasonable compromise that doesn't quite create a thousand planets in the solar system, using parameters that will be rife with chaotic interpretation.

Guess I'm just too much in favor of some sort of "order" in a field of science that is probably more in flux than that of any other.

A2K

[Matt-hurricanewatcher]

It would be easy if Pluto was just the lower limit...Yes theres likely to be many more found. But some one very smart once said "Make it simple but not to simple". Which means make it work for all solar systems. Keep the system we got kind of now which says a planet is a sphere and add a base line of no smaller then pluto. In yes theres going to be some weird things if we try to make it harder then this. We don't need to rewrite a THE TAX book of planety science like we have to do taxs. Keep it simple.

[Terrell]

There is really no scientific point in setting a lower limit of the size of a planet at Pluto. The only reason to do so is sentimental. If it lives in the Kuiper belt like a KBO and is made of rock and ice like a KBO, it's a KBO whether it was discovered in 1930 by Clyde W. Tombaugh, or it was discovered after 1992 QB1, that includes 2003 UB 313 (Xena).

Pluto and 2003 UB 313 differ from the other (known) Kuiper Belt Objects (KBOs) only in their size though Pluto does have much popular support for being called a planet. It's almost as if calling Pluto a KBO is picking on it, though I don't think KBOs have feelings.

[streetsoldier]

Hmmm, "Xena", is it? What's next, "Gabrielle"?

[Matt-hurricanewatcher]

Pluto and Mercury are not much different.

1# They are both small. Many of the moons around Jupiter are bigger.
2# Mercury could be some weird Astroid that got picked up by the sun like the two moons around mars.

So if pluto go's then Mercury will be nexted to be looked at...O yes Just like Pluto is in a belt of objects rock,ice. Guest what Earth,Venus,Mars,Mercury. In yes the gas giants start out. They started out like a disk of rock around the sun which came together because of gravity. The gas giants are so because they did not get there Atmosphere blow to heck.

Mercury if Pluto go's I'm looking at you! Also Mercury is only twice the size of Pluto at 4,480 km di. Pluto is 2,300-2400km something like that.

[Aslkahuna]

Xena is an unofficial name-there has been no name assigned to that object by the IAU yet. The moons of Saturn (aside from Titan) are so small in terms of mass that the barycenter of the Saturnian system may very well reside in the actual core of the planet. Even more so for Jupiter since it holds 98% of the mass of all non Solar objects in our system so despite that fact that it has 4 moons of quite large size (including one larger than Mercury) the barycenter is not likely to be too far from the center of the Planet. Incidentally. the barycenter of the Solar System is offset by a small amount in the direction of Jupiter.

Steve

[Terrell]

Hmmm, "Xena", is it? What's next, "Gabrielle"?

Xena does have a moon and it's discoverers are calling it Gabrielle. The IAU of course will eventually have to give the bodies official names.

http://www.gps.caltech.edu/~mbrown/planetlila/moon/index.html

[Terrell]

Pluto and Mercury are not much different.

1# They are both small. Many of the moons around Jupiter are bigger.
2# Mercury could be some weird Astroid that got picked up by the sun like the two moons around mars.

So if pluto go's then Mercury will be nexted to be looked at...O yes Just like Pluto is in a belt of objects rock,ice. Guest what Earth,Venus,Mars,Mercury. In yes the gas giants start out. They started out like a disk of rock around the sun which came together because of gravity. The gas giants are so because they did not get there Atmosphere blow to heck.


Mercury if Pluto go's I'm looking at you! Also Mercury is only twice the size of Pluto at 4,480 km di. Pluto is 2,300-2400km something like that.

Pluto is in the Kuiper belt, it's made like the KBO's it's similiar in mass to them, it's a little larger than most of the ones we've already discovered, but we've only known for sure that the Kuiper Belt existed since '92, in time we'll likely find hundreds of KBOs comparable to Pluto.

Mercury isn't in or even near a belt. Mars and Jupiter are near belts, namely the Asteroid belt, but they are not like the Asteroids, they're clearly different, in terms of mass. size, and in Jupiter's case composition.

Neptune is near the Kuiper belt, and exerts gravitational influence on them, quite a few of them are gravitationally locked in a 3:2 resonance with Neptune, Pluto included. Neptune though is clearly different in comosition, size, and mass to the KBOs being a gas giant and all.

Mercury and Pluto are NOT the same in composition. Read the wikipedia entries from the 2 celestial bodies and the differences between the two are obvious. Mercury is a planet, Pluto is a Kuiper Belt Object.


http://en.wikipedia.org/wiki/Pluto

You'll have to cut and paste the Mercury wikipedia link, for some reason the forum won't take the link, I've edited several times and it just won't accept it as a link. btw there's an underline _ not a space between Mercury and (planet)

http://en.wikipedia.org/wiki/Mercury_(planet)

[Audrey2Katrina]

The moons of Saturn (aside from Titan) are so small in terms of mass that the barycenter of the Saturnian system may very well reside in the actual core of the planet.

Perhaps they do...possible... especially for the so-called "shepherd moons"... but there is that sticky situation with Titan. Titan is a monster among the moons and I seriously doubt its barycenter with Saturn would rest within the "core" of the planet itself. Does this mean we rethink Titan as well, and call it a planet?

The point about the same with regard to the solar system itself is an interesting codicil in and of itself. I guess we'll just have to wait and see what the "committees" within, or the powers that be decide. Personally, I feel that regardless of what they decided, it'll be an awfully hard sell to get folks to call Pluto and its moon. both planets... sort of like the rebellion when they tried to change Coke... (okay that was a joke!) but the point is similar--you'll still have a huge majority of folks who simply will stick with the "classic" nomenclature, at least for long enough of a time period to cause some possible rethinking--JMO. I mean I STILL hear people, to this day insisting that it's Haley's (Pronounced Hay-Lee's) Comet... even after all the efforts to "educate" the masses about its "correct pronunciation" back in 86.

Change is the natural state of existence in this universe, sometimes absolutely necessary, and at others, somewhat arbitrary--but always interesting; and it is in the nature of many--if not most--humans to resist change--even when it is often for the greater good. Just a thought.

A2K

[brunota2003]

I have a question...Why cant we just stick with the 9 we have? why must we go look for more? IMHO I hope the experts remember all of this stuff...because it just confuses the crap out of me...

[Terrell]

I have a question...Why cant we just stick with the 9 we have? why must we go look for more? IMHO I hope the experts remember all of this stuff...because it just confuses the crap out of me...

If we stop looking we stop learning about our Solar System. Thing is we really only have 8 true planets, the IAU is just afraid of the backlash that would come if they no longer count Pluto. The problem is that it would be intellectually dishonest if they don't count "Xena" because she's slightly bigger than Pluto even though both really aren't deserving of planet status being they're both really Kuiper Belt Objects.

When Pluto was discovered in 1930, during a deliberate search for a planet beyond Neptune, we didn't know about the Kuiper Belt, Gerard Kuiper hadn't theorized it's existence yet, and there was no reason to believe that there was a belt of icy bodies beyond Neptune. It wasn't known for sure that there were other bodies beyond Neptune besides Pluto until 1992, by then Pluto was well known as a Planet (although mistakenly) and people, especially in the US, are resistant to changing that status even though it's pretty clear that Pluto isn't a planet.

[kevin]

Did anyone catch the interview on the Colbert Report about this?

[Terrell]

Did anyone catch the interview on the Colbert Report about this?

Yeah with Neil deGrasse Tyson last night. Personally I think that Tyson is right about putting Pluto with the KBOs in his display, calling Pluto a planet is really just a cultural thing it's been called a planet since it was discovered and people don't want to change it. Oh and stop sending him hate mail for not putting Pluto in his display of the 8 planets.

Give Pluto KBO status which is what it should have, a minor planet number (which is apropriate for things like asteroids and KBOs), and make up a new mnemonic for the planet names. It could simply say "My Very Educated Mother Just Served Us Noodles" or something like that. Change the history books to put Clyde Tombaugh as the discoverer of the first KBO rather than Jewitt and Luu. And make the Science books reflect 8 planets until there is actually another planet discovered that is NOT in the Kuiper belt.

[kenl01]

I think my dad had it right when he said "I don't think they (scientists) know anything what's going on............

too much theory that doesn't amount to anything but speculation.

[Terrell]

Theory in science is a bit more than just speculation. More can be found by following the link in the quote.

In science, a theory is a proposed description, explanation, or model of the manner of interaction of a set of natural phenomena, capable of predicting future occurrences or observations of the same kind, and capable of being tested through experiment or otherwise falsified through empirical observation. It follows from this that for scientists "theory" and "fact" do not necessarily stand in opposition. For example, it is a fact that an apple dropped on earth has been observed to fall towards the center of the planet, and the theory which explains why the apple behaves so is the current theory of gravitation.

http://en.wikipedia.org/wiki/Theory