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Pluto/Neptune resonance question
Given that :
A.) Pluto crosses Neptune's orbit. B.) Pluto's orbital plane is offset from the major planets. C.) Neptune's moon Triton has a retrograde orbit, and is apparently a gravitationally captured object. Do Pluto and Neptune engage in some sort of long-term resonance relationship so that Pluto never crosses Neptune's orbit while being in the same plane and place as Neptune at the same time? Is the reason that Pluto's orbital plane is skewed from the other planets due to a close encounter with Neptune in the distant past that put it into its present orbit? Pat |
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Pluto/Neptune resonance question
Pat Flannery wrote in
: Do Pluto and Neptune engage in some sort of long-term resonance relationship so that Pluto never crosses Neptune's orbit while being in the same plane and place as Neptune at the same time? Is the reason that Pluto's orbital plane is skewed from the other planets due to a close encounter with Neptune in the distant past that put it into its present orbit? Neptune and Pluto have a 3:2 resonance; Neptune completes 3 orbits to Pluto's 2. I assume the dog wags the tail in this case, and that may help to make the case that Pluto should not be considered a planet. http://en.wikipedia.org/wiki/Pluto --Damon |
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Pluto/Neptune resonance question
Damon Hill wrote: Pat Flannery wrote in : Do Pluto and Neptune engage in some sort of long-term resonance relationship so that Pluto never crosses Neptune's orbit while being in the same plane and place as Neptune at the same time? Is the reason that Pluto's orbital plane is skewed from the other planets due to a close encounter with Neptune in the distant past that put it into its present orbit? Neptune and Pluto have a 3:2 resonance; Neptune completes 3 orbits to Pluto's 2. I assume the dog wags the tail in this case, and that may help to make the case that Pluto should not be considered a planet. http://en.wikipedia.org/wiki/Pluto --Damon In the current era, the resonance works in such a way that Neptune is never near the point of its orbit when Pluto crosses it. Also, it's not so apparent in 2D pictures, but due to Pluto's inclination, when it crosses Neptune's orbit in terms of solar distance, it is many AUs above or below that orbit. You'll have someone else about how the situation has evolved over time. |
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Pluto/Neptune resonance question
On Sat, 26 Aug 2006 02:37:22 -0500, Damon Hill
wrote: Pat Flannery wrote in : Do Pluto and Neptune engage in some sort of long-term resonance relationship so that Pluto never crosses Neptune's orbit while being in the same plane and place as Neptune at the same time? Is the reason that Pluto's orbital plane is skewed from the other planets due to a close encounter with Neptune in the distant past that put it into its present orbit? Neptune and Pluto have a 3:2 resonance; Neptune completes 3 orbits to Pluto's 2. I assume the dog wags the tail in this case, and that may help to make the case that Pluto should not be considered a planet. http://en.wikipedia.org/wiki/Pluto --Damon Is there a chance of them ever colliding? |
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Pluto/Neptune resonance question
NoBody Here wrote in message ... Neptune and Pluto have a 3:2 resonance; Neptune completes 3 orbits to Pluto's 2. I assume the dog wags the tail in this case, and that may help to make the case that Pluto should not be considered a planet. http://en.wikipedia.org/wiki/Pluto --Damon Is there a chance of them ever colliding? Not in any timeframe we can accurately predict. |
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Pluto/Neptune resonance question
Greg D. Moore (Strider) wrote: Is there a chance of them ever colliding? Not in any timeframe we can accurately predict. I still think the reason Pluto's orbit is odd is that some point in the past it did have a close encounter with Neptune that shifted its orbit. Pat |
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Pluto/Neptune resonance question
"Pat Flannery" wrote in message ... I still think the reason Pluto's orbit is odd is that some point in the past it did have a close encounter with Neptune that shifted its orbit. And, shortly thereafter, Checkov failed to remember he'd been there before, and he was then captured by Khan and friends (notice that, during their stay, the planetary conditions favored the survival of youthful-looking Caucasians; the strain of leadership must have aged Khan). |
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Pluto/Neptune resonance question
In article ,
Pat Flannery wrote: A.) Pluto crosses Neptune's orbit. Only in a 2-D plot. Not in three-dimensional space. Do Pluto and Neptune engage in some sort of long-term resonance relationship so that Pluto never crosses Neptune's orbit while being in the same plane and place as Neptune at the same time? Yes. As noted above, the orbits don't actually intersect. Also, they are in a 3:2 resonance such that Pluto avoids Neptune -- the "crossings" occur near Pluto's perihelion, but Pluto's closest approaches to Neptune occur at Pluto aphelion. There are 40ish other "Plutinos", KBOs in similar 3:2 resonances with Neptune. Plus some other KBOs in more distant resonances. Is the reason that Pluto's orbital plane is skewed from the other planets due to a close encounter with Neptune in the distant past that put it into its present orbit? The past history of resonant systems is difficult to determine, because settling into the resonance tends to destroy the evidence. :-) But KBO orbital inclinations vary a lot more than those of the major planets, so there is no obvious *requirement* for such an encounter to have occurred. Pluto's orbital plane looked strange when it was the only one of its kind, but is now seen as nothing very unusual. -- spsystems.net is temporarily off the air; | Henry Spencer mail to henry at zoo.utoronto.ca instead. | |
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Pluto/Neptune resonance question
Henry Spencer wrote: In article , Pat Flannery wrote: A.) Pluto crosses Neptune's orbit. Only in a 2-D plot. Not in three-dimensional space. Do Pluto and Neptune engage in some sort of long-term resonance relationship so that Pluto never crosses Neptune's orbit while being in the same plane and place as Neptune at the same time? Yes. As noted above, the orbits don't actually intersect. Also, they are in a 3:2 resonance such that Pluto avoids Neptune -- the "crossings" occur near Pluto's perihelion, but Pluto's closest approaches to Neptune occur at Pluto aphelion. According to a synodic period program I have, Neptune and Pluto are in conjunction once every 492.4 years. I haven't worked the numbers but I'm curious about when the last such conjunction occurred and when the next one will be. Just ran another program and found the last Neptune/Pluto conjunction to around mid May 1883. So the next one will be early in the 2376. Also I noted that the conjunctions are moving three degrees toward Pluto aphelion per conjunction, the last being at about 60 degrees and then next at 57 degrees, whereas Pluto aphelion is about 45 degrees. All degrees in heliocentric coordiantes with 0 degrees being the first point of Aries. Eric There are 40ish other "Plutinos", KBOs in similar 3:2 resonances with Neptune. Plus some other KBOs in more distant resonances. Is the reason that Pluto's orbital plane is skewed from the other planets due to a close encounter with Neptune in the distant past that put it into its present orbit? The past history of resonant systems is difficult to determine, because settling into the resonance tends to destroy the evidence. :-) But KBO orbital inclinations vary a lot more than those of the major planets, so there is no obvious *requirement* for such an encounter to have occurred. Pluto's orbital plane looked strange when it was the only one of its kind, but is now seen as nothing very unusual. -- spsystems.net is temporarily off the air; | Henry Spencer mail to henry at zoo.utoronto.ca instead. | |
#10
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Pluto/Neptune resonance question
This lists my contribution/modification to an item
originally by Tony Hoffman: What has resonance to do with if an object should be considered a planet? Earth and Mars are in an 2:1 resonance, does that mean something other than one orbits twice the time of the other? Of course not. Clearing their space in orbit? Again not, look at Jupiter and the difficulty it has clearing the Trojan asteroids it orbits with. The earth has a near miss with asteroids every other day, I can email you the actual list. Does that mean the earth is not considered a planet? Of course not. What about Jupiter-sized extrasolar planets that cross each other's orbit in 2-D only and exhibit resonance? Of course they are both planets. (DRL) It's now been some time since the International Astronomical Union (IAU) stripped Pluto of its planethood. In choosing the more stringent of two competing definitions of the term planet, the IAU has booted Pluto into a new underclass of "dwarf planets", and seemingly capped the solar system's planet total at eight. Many scientists aren't pleased with the new solar-system order, saying it's imprecise and too restrictive. The ancient Greeks called the points of light that roved along the zodiac planetes: wanderers. But despite the discovery of several new planets since the invention of the telescope, astronomers never defined what a planet actually was. When Ceres, Pallas, Juno, and Vesta were discovered in the early 1800s, they were originally considered planets, but later reclassified as asteroids. Pluto, discovered by Clyde Tombaugh of Lowell Observatory in 1930, proved to be much smaller than originally thought, smaller than Earth's moon, leading some astronomers to call for its demotion. But it was Caltech astronomer Mike Brown's discovery of an ice-world slightly larger than Pluto, which he nicknamed "Xena", that brought the issue to a head, many wondered whether Xena be classified as a planet, or a mere asteroid? And however Xena went, Pluto was likely to follow. The initial definition proposed by an IAU committee in August defined a planet as an object that orbits the Sun and is large enough so that its gravity holds it in a near-spherical shape. Opponents claimed that this definition would permit tens or hundreds of puny poseurs to become planets (though the proposal took care to distinguish the eight "classical planets" from Pluto and the upstarts), and it would be confusing to students and the public. Almost no one has to memorize the entire periodic table of the elements, yet everyone knows oxygen, carbon, iron, and other key elements. So, kids would learn of "Xena" (whatever it is ultimately named), as well as far-ranging, reddish Sedna, several large, exotically named iceballs (Quaoar, Ixion, Orcus, and Varuna), a football-shaped world known only as 2003 EL61, and other worlds as yet undiscovered. (TH) It is sad and pathetic that astronomy has become a war between planetary geologists, who study the structure and composition of worlds, and orbital dynamicists, who are concerned with planetary motion. The latter group forced the inclusion of a provision that to be a planet, an object must have "cleared the neighborhood around [its] orbit". This rules out Pluto which orbits amid a flock of similar (yet mostly smaller) iceballs in a region known as the Kuiper Belt. Ceres, the largest asteroid; both are being reclassified as dwarf planets. But what of Neptune? It hasn't cleared away pesky Pluto, nor the Kuiper-belt objects that cross its orbit. Even Jupiter has an array of Trojan asteroids before it and after it cannot seem to "clear the way" with gravity so strong that it is almost a star. It is not a star because it does not light up from thermonuclear fusion. So it seems that the IAU definition is not scientific either, and it is decidedly unpopular. That is because everyone reading about it seems to come to the same conclusion, that is, that the IAU should have better things to do with its time and more importantly "our tax money" that supports the grants received by astronomers in general. (DRL) And by the new definition, Earth, which lies in a cosmic shooting gallery of tens of thousands of asteroids that potentially could collide with us shouldn't be a planet. (As to whether there's intelligent life here, I'll leave that to a future discussion. The solar system was due for a reclassification, to keep up with new discoveries. It made sense for the IAU to call Pluto the prototype for a new type of "trans-Neptunian" object, world, or planet, but that and planethood need not be mutually exclusive. Any definition of planet is some-what arbitrary; it's not as if objects are hung with tags that say "I'm a planet!" Faced with competing definitions, both with some scientific merit, the IAU went the restrictive route. Even as telescopes reveal new and exotic denizens of the outer solar system, we've gone and shrunk the solar system. Pluto's gotten the boot, and dwarf planets by definition aren't true planets. (Perhaps a better name for them would be planettes or worldlets.) Even many of the astronomers who supported the new order admit a twinge of sadness over Pluto's demotion. The new system is not only imprecise, but it's demoralizing. People are inspired by the idea of new planets in a way that they're never likely to be for lesser solar system bodies. (TH) It might do well if astronomers borrowed from the biologist's species and genus system of organization of plants and animals. After all, no one has demoted mice from the animal kingdom because they are small. Here we would have anything not a star considered a planet and divided into classes. Examples might be Ice Giant, Gas Giant, Solid, Water, Ice, Proto, Extra-solar or Independent (a planet not in a solar system at all but drifting between stars). Words like terrestrial type or lunar type or Mars Type come to mind. The relative orbital movement would not be important, that is, a planet in another solar system of 12 Jupiter masses but in a highly elliptical orbit would not be disqualified. Another simple way might include a defintion that if a proposed new object were viewed at the distance of Saturn from the earth, mathematically would the new object be readily visible to the naked eye? (at least 3rd Magnitude) Such math is very easy to do and sounds better than demoting existing planets. By the way, Saturn was the most distant planet the Greeks could see and it's their word we are borrowing just as I am borrowing part of Tony Hoffman's news item here.(DRL) Darrell Lakin Smithfield, Virginia Henry Spencer wrote: In article , Pat Flannery wrote: A.) Pluto crosses Neptune's orbit. Only in a 2-D plot. Not in three-dimensional space. Do Pluto and Neptune engage in some sort of long-term resonance relationship so that Pluto never crosses Neptune's orbit while being in the same plane and place as Neptune at the same time? Yes. As noted above, the orbits don't actually intersect. Also, they are in a 3:2 resonance such that Pluto avoids Neptune -- the "crossings" occur near Pluto's perihelion, but Pluto's closest approaches to Neptune occur at Pluto aphelion. There are 40ish other "Plutinos", KBOs in similar 3:2 resonances with Neptune. Plus some other KBOs in more distant resonances. Is the reason that Pluto's orbital plane is skewed from the other planets due to a close encounter with Neptune in the distant past that put it into its present orbit? The past history of resonant systems is difficult to determine, because settling into the resonance tends to destroy the evidence. :-) But KBO orbital inclinations vary a lot more than those of the major planets, so there is no obvious *requirement* for such an encounter to have occurred. Pluto's orbital plane looked strange when it was the only one of its kind, but is now seen as nothing very unusual. -- spsystems.net is temporarily off the air; | Henry Spencer mail to henry at zoo.utoronto.ca instead. | |
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