new planet definition proposal

[MeteorWayne]

I don't believe the moon will ever leave the earth's orbit, at least not until we're crisped nicely by the sun. By then, who cares. I could be wrong about that, though. Anybody researched this?<br /><br />Also, it's not too likely that there are smaller planets inside the orbits of the elliptical gas giants around other planets.<br />Gas giants tend to either eject such rubble from the system, smash into them, or throw them into the star. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[ittiz]

The moon is receding from the Earh about an inch and a half every year. This is why people were saying under the first definition the moon could become a planet eventually. Because once it gets far enough away the Earth and Moon barycenter will be outside Earth.<br /><br />If a rouge gas giant planet entered a system from above or below the elliptic it could very well not interact with the orbit of the other planets. Odds are the gas giant planets with elliptical orbits around other stars are rouge planets that have done just that. I'm sure that in many of these systems the smaller planets have been left relatively undisturbed.

 

[MeteorWayne]

I don't think there's any evidence one way or the other that the GG's are rogue planets. More likely IMO is that they are the result of the same flat disk process that formed our system.<br /><br />Energy wise, it've very difficult to capture a rogue planet. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[ittiz]

Note that I said elliptical orbits. The current theory is that the elliptically orbiting gas giants are captured rouge planets. I personally can't think of any way a gas giant that formed naturally would get into an elliptical orbit without being a rouge first.

 

[MeteorWayne]

I have to disagree, I'll do some checking.<br />It's actually quite likely that planets wind up in elliptical orbits.<br />What's harder to explain is how our solar system turned out so nice.<br /><br />Our gas giant just happens to have developed in a nice circular orbit, which is very fortunate, or we wouldn't be here! <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[vandivx]

<<"I don't consider him prominent, five years ago possibly, not today. While his rif raf about a high amount of objects might be valid, it looks like he want to gain prestige by talking.">><br /><br />I didn't mean prominent professionally, don't know much about that, maybe better way to put it is 'known' by public, Czech public that is, and newspapers typically turn to him because he is available and can speak human language to them, if you tortured me now, I wouldn't be able to name another Czech astronomer's name, that's what I meant<br /><br />as to 'prestige' I believe it is more that nespaper reporters simply turned to him because of his past record with them and possibly he had been willing to talk to them even if he might not have had time to spare, that's because he would have seen talking to public as important, not something to be scoffed at, perhaps in contrast to other astronomers<br /><br />vanDivX <div class="Discussion_UserSignature"> </div>

 

[ittiz]

The liquids on planets circularize thier orbits. Gas giants have liquid hydrogen, and all planets probably have a liquid molten surface during thier early years. Also you have to remember that the bodies end up with the average of the mometum of the bodies that formed them. Which is probably why the smaller bodies have wierd orbits. So for a gas giant to have a naturally elliptical orbit I would think that most of the bodies that formed it would have to have elliptical orbits in the same way. Which I guess could happen if another star got really close and perturbed stuff, but I think that it would mostly strip stuff away.

 

[MeteorWayne]

Can you explain a mechanism that liquids on planets circularize their orbits?<br />I can't imagine one.<br /><br />Could be circular logic, perhaps. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[raghara2]

Definition of a planet.<br /><br />mass is higher than 4E23 kg<br />or <br />diameter is larger than 5000 km (largest diameter of course)<br /><br />Thus Mercury isn't a planet.<br /><br />Anything smaller is PBO. (Planetlike object type B)<br /><br />I consider it as a significantly more useful definition than the above.<br />

 

[raghara2]

"I didn't mean prominent professionally, don't know much about that, maybe better way to put it is 'known' by public"<br /><br />He was a lot of in TV before revolution. Then journalist knew him, so they asked him frequently to come into TV, and about astronomy things, even after that.<br /><br />However he acts as a jerk in other activities, so he makes me uneasy.<br /><br />

 

[Philotas]

"Finally the reason won over sentiment. "<br /><br />No..not at all. It's 100% on the contrary. <i>Sentiment</i> won. There is no scientific support behind the part of the definition that says that "the object would have to be 100 times more massive than anything else that shares it's orbit", not at all. It's purely sentimental just to keep the planet count low. Taxonomy won over science today. <img src="/images/icons/frown.gif" /> <div class="Discussion_UserSignature"> </div>

 

[Philotas]

It's not scientifical, and 100% arbitrary(apart from the fact that it keep the planet count low, as it's supposed to do). As well it will work <i>very</i> bad in other solar systems. <div class="Discussion_UserSignature"> </div>

 

[raghara2]

<font color="red">I personally can't think of any way a gas giant that formed naturally would get into an elliptical orbit without being a rouge first. </font><br /><br />It's actually pretty easy. Close encounter in stellar nursery could rob it of some energy. One of original binary was ejected from system... <br />Starting condition.<br />Modification of the trajectory by an eliptical star companion.<br />Majority of an eliptical orbits if large planets are not that much eliptical to bother small planets in the system.<br />

 

[ittiz]

It has something to do with tides. It was actually one of the major arguments against a global ocean on Titan before Cassini got there.

 

[ittiz]

True but there are still some know about that are quite elliptical.

 

[rhm3]

"Hey did you hear Pluto is not a planet anymore?"<br />"Wow no, what is it?"<br />"It's a...errr, dwarf planet."<br />"..."<br /><br />Yep, this definition is made to cater ONLY our own solar system...notice "the Sun" is used in the wording, not "a star." There is no way this definition will hold for other stellar systems. <br /><br />Clearing orbital mass...heh...the Kuiper Belt is wider than the inner solar system. So how wide do they consider "orbit"? The inner planets were able to clear their orbits easier due to the presence of Jupiter anyways. <br /><br />They just want a countable number of planets. So now Mercury is in a different class than Pluto, but the same one as Jupiter. Yeah, that makes sense. <br /><br />This debate isn't over. Just wait til we find an Earth-sized "dwarf planet" beyond Pluto...and such an object (or multiple) is entirely possible.

 

[Philotas]

"Yep, this definition is made to cater ONLY our own solar system...notice "the Sun" is used in the wording, not "a star." There is no way this definition will hold for other stellar systems."<br /><br />Ok, thx man. Didn't notice. :S <div class="Discussion_UserSignature"> </div>

 

[rhm3]

lol just stating my thoughts when I saw it, I see thats been pointed out already.<br /><br />But another thing...I'm ok with the term dwarf planet. However, I'd define it based on size, not "orbtial clearance." Also, it should be a category of planets, as its name so obviously suggests.

 

[llivinglarge]

What happens to Charon?

 

[MeteorWayne]

Good question.<br />A moon or a binary dwarf.<br />My guess would be the latter. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[jmilsom]

I don't like the new proposal. I don't think smugly arguing finally reason won out over sentimentality holds either. <br /><br />I note they say <font color="yellow">A dwarf planet is not a planet</font><br /><br />Does this mean a person with dwarfism is not a person? <div class="Discussion_UserSignature"> </div>

 

[JonClarke]

This new definition is nuts. So planets are objects that have cleared their neighbourhood? So when we look at the early solar system we find a period when there were a large number of planet sized bodies is a wide range of orbits that cannot be called planets because they had not yet cleared their neighbourhood? No only does this classification break down in the early solar system it will be utterly useless in extrasolar systems that too are in the early stage of their evolution.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[JonClarke]

The problem is it is completely arbitary.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[jmilsom]

I agree completely Jon. I saw the definition you proposed in one of the other planet naming threads (there are so many of them now) and thought it was spot on. <br /><br />I am confused as to what happened in the IAU. For days everyone was talking about the new definition which would give us 12 planets - there were some flaws, but it was an improvement. And then suddenly at the end of the process, a new proposal that seems rather flimsy gets through. <br /><br />I guess I don't understand the politics of the upper levels of the IAU. Why did only 424 astronomers get to vote? <div class="Discussion_UserSignature"> </div>

 

[Saiph]

well, the requirement that a planet must have cleared it's orbital region does break down in forming solar systems. However, that basically means that the object is likely a proto-planet, so it really isn't an issue there.<br /><br /><br />Anyway, as for having 400 odd astronomers be the only one to vote: Quick question, how many astronomers do you think there are?<br /><br />Answer: Less than 10,000 worldwide IIRC. So basically 1 in a 25 or so got to vote. <div class="Discussion_UserSignature"> <p align="center"><font color="#c0c0c0"><br /></font></p><p align="center"><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">----</font></em></font><font color="#666699">SaiphMOD@gmail.com </font><font color="#999999"><em><font size="1">-------------------</font></em></font></p><p><font color="#999999"><em><font size="1">"This is my Timey Wimey Detector.  Goes "bing" when there's stuff.  It also fries eggs at 30 paces, wether you want it to or not actually.  I've learned to stay away from hens: It's not pretty when they blow" -- </font></em></font><font size="1" color="#999999">The Tenth Doctor, "Blink"</font></p> </div>