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Kullat Nunu
2005-Apr-01, 01:04 PM
Space.com: Five Out of Five Researchers Agree: Earth's Solar System Special (http://www.space.com/scienceastronomy/050331_asimov_debate.html)


Though researchers find more and more distant planets revolving around alien suns, the discoveries highlight that Earth and its solar system may be an exceptionally rare place indeed.

That was the consensus here Wednesday evening among five planetary science experts who spoke at the 5th annual Isaac Asimov Memorial Panel Debate held at the American Museum of Natural History.

Argos
2005-Apr-01, 01:08 PM
As for the first paragraph of your quote, I believe it´s too premature saying that. We´ve got a long way to go.

Padawan
2005-Apr-01, 01:32 PM
As for the first paragraph of your quote, I believe it´s too premature saying that. We´ve got a long way to go.


Indeed, that is my opinion too. Our equipment today isnt good enough to detect earth sized planets (and smaller planets too!) easily.

Argos
2005-Apr-01, 01:52 PM
Yeah. There´s a selection effect (I know you´re aware of it). We discover the big ones because the big ones is what we can afford by now.

2005-Apr-01, 02:06 PM
As our sample size is just ONE, I too, think it a tad premature for making leaps of faith concerning what lies out there in the Universe?? :D :D :D

eburacum45
2005-Apr-01, 02:40 PM
But the sample size is much bigger now, since 150+ extrasolar planets have been charted;
the argument should be that it is a skewed sample, distorted by the fact that only large planets can be detected, and the ones which are closest to their primary will be detected first.
Margret Turnbull made a similar point in that link, I believe.

Bozola
2005-Apr-01, 04:07 PM
Too bad it is about to be bulldozed to make way for a bypass.

John Dlugosz
2005-Apr-01, 04:29 PM
two words: Observer Bias.

The ones with the largest, fastest planets are the first to be discovered.

Ilya
2005-Apr-01, 05:34 PM
Did any of you actually read the article?


“I have a problem referring to our own solar system as unusual, because we haven’t done that experiment yet, we haven’t searched for our own solar system yet,” said Turnbull Thus far, the kind of data obtained and the type of observations made are tuned to search for Jupiters and not Earths, therefore that’s what we find. “The experiments were designed for that,” she explained.

But with the vast majority of the alien planets found in eccentric orbits, Butler has a different view. “I think with the data at hand, we can say that our solar system is rare. Eccentricity dominates,” said Butler. “It’s just a matter of how rare we are,” he added.

No one claims that lack of observed Earth-size planets makes our solar system special. That would be asinine, for it is entirely Observer Bias. The point of the article is that if you exclude "hot Jupiters" (prevalence of which is also Observer Bias), then almost all extrasolar planets are in eccentric orbits. That is not Observer Bias, is definitely different from Solar System, and does not bode well for terrestrial planets (other than moons of giant planets).

Ricimer
2005-Apr-01, 06:04 PM
however there is also a selection effect for eccentric orbits.

The current methods detect "extremes" High mass, close orgits, eccentric orbits.

We haven't found enough smaller planets for me to accept that conclusion. it may be leaning that way.

Then again, out of the 8 major planets in our system (pluto is a KBO) they all have circular orbits...

Ilya
2005-Apr-01, 06:10 PM
however there is also a selection effect for eccentric orbits.

The current methods detect "extremes" High mass, close orgits, eccentric orbits.

Do you have a link for that? To the best of my knowledge, Doppler method is not affected by eccentricity; the bias is only toward high mass and close orbits.

Kullat Nunu
2005-Apr-01, 06:26 PM
As for the first paragraph of your quote, I believe it´s too premature saying that. We´ve got a long way to go.

I definitely agree with that. There is very strong selection effect.

But, still no true Jupiter analogs (Jupiter-mass planets in distant circular orbits) have been found. Waiting anxiously...

Ilya
2005-Apr-01, 06:45 PM
Here is the up-to-date list of confirmed planets around main sequence stars (http://www.obspm.fr/encycl/cat1.html). It is arranged in order of semi-major axes; in case of multiple planet systems, the list uses the semi-major axis of the innermost planet. Every planet with semi-major axis above 1 AU has eccentricity of at least 0.1, and usually a lot more.

Swift
2005-Apr-01, 08:03 PM
Here is the up-to-date list of confirmed planets around main sequence stars (http://www.obspm.fr/encycl/cat1.html). It is arranged in order of semi-major axes; in case of multiple planet systems, the list uses the semi-major axis of the innermost planet. Every planet with semi-major axis above 1 AU has eccentricity of at least 0.1, and usually a lot more.
Neat website Ilya, thanks for the link.

Plat
2005-Apr-02, 02:48 AM
So is it special?

But yeah I think it is kind of premature

Kullat Nunu
2005-Apr-02, 12:32 PM
Here is the up-to-date list of confirmed planets around main sequence stars (http://www.obspm.fr/encycl/cat1.html).

The Extrasolar Planets Encyclopaedia is probably the most authoritative extrasolar planet catalogue in the net. Surely it is the oldest since it started in the early 1995, well before the discovery of 51 Pegasi b.

A.DIM
2005-Apr-02, 02:57 PM
I'm very intrigued by the possibility that our solar system is "special."

In my mind, some sort of perturber, possibly still present, could explain the distribution of material & angular momentum, the relatively circular orbits, as well as various other puzzles we see in our system.

I must agree, however, that the sample size and observer bias, coupled with a need for better tech, leaves us in no position to say with any certainty one way or another.

R.A.F.
2005-Apr-02, 03:33 PM
In my mind, some sort of perturber, possibly still present, could explain the distribution of material & angular momentum, the relatively circular orbits...

Actually a lack of a "pertuber" would explain relatively circular orbits better...


...as well as various other puzzles we see in our system.

And what would those "other puzzles" be???

Also...how does your post relate to the discussion in this thread, ie. extra-solar planets? If you want to start a "pertuber" discussion, I would suggest you post it where it belongs, in Against the Mainstream.

A.DIM
2005-Apr-02, 11:40 PM
In my mind, some sort of perturber, possibly still present, could explain the distribution of material & angular momentum, the relatively circular orbits...

Actually a lack of a "pertuber" would explain relatively circular orbits better...

Uh, somehow this remark strikes me as contrary to what the article itself dealt with.... but ok.

Explain please?

And what about the angular momentum issue?



...as well as various other puzzles we see in our system.

And what would those "other puzzles" be???

-Sedna, CR105, 2004DW?
-Pluto?
-Uranus?
-retrograde motion?
-Astreroid Belt?
-Earth - Moon system?


Also...how does your post relate to the discussion in this thread, ie. extra-solar planets? If you want to start a "pertuber" discussion, I would suggest you post it where it belongs, in Against the Mainstream.

My post was most relavant to this topic, RAF, and should've been clear, when taken in it's entirety: The issue is what makes our solar system special; why ours appears to be so unique. I proffered an idea.

But you, you show up playing mouthpiece or "improper posting place police" or something. :roll:

R.A.F.
2005-Apr-03, 01:05 PM
My post was most relavant to this topic, RAF, and should've been clear, when taken in it's entirety...

Obviously, I disagree.


I proffered an idea.

You injected "perturber" into the conversation. Your "brand" of perturber is unproven...that makes it not general astronomy.


But you, you show up playing mouthpiece...

Mouthpiece to whom?? My posts are my opinions.


...or "improper posting place police" or something. :roll:

If you have a difficulty with the way I post, PM the BA and complain...if you're unwilling to do that, then stop complaining.

Plat
2005-Apr-03, 03:41 PM
Do you think that Sun-like stars would have planets in position like over here.

Hazzard
2005-Apr-04, 12:56 PM
Do you think that Sun-like stars would have planets in position like over here.

Iwould think so...but the interesting part for me is..

-Are there any planets in the "friendly distance" to that star.??

You know,not to cold and not to hot.

Outcast
2005-Apr-04, 06:00 PM
If you have a difficulty with the way I post, PM the BA and complain...if you're unwilling to do that, then stop complaining.

its incredible that in a place where flammers and trolls are obliterated before even engaging full throttle someone like R.A.F. could amass 3000+ posts under his belt. why the BA lets this happen is a mystery in my mind.

Vermonter
2005-Apr-04, 06:19 PM
Now, these planets are orbiting single stars? Or are they part of a binary system?

Kullat Nunu
2005-Apr-04, 06:26 PM
Now, these planets are orbiting single stars? Or are they part of a binary system?

Some of them are in binary systems. For example 55 Cancri, Tau Boötis, Upsilon Andromedae, Gamma Cephei, and 16 Cygni are binary stars. Except for Gamma Cephei they are wide systems.

A.DIM
2005-Apr-04, 06:35 PM
My post was most relavant to this topic, RAF, and should've been clear, when taken in it's entirety...

Obviously, I disagree.

Obviously.
But are you going to answer my questions?



I proffered an idea.
You injected "perturber" into the conversation. Your "brand" of perturber is unproven...that makes it not general astronomy.

“Injected” my “brand” of perturber, RAF? :roll:
Once again we find you reading too much into something and making utterly baseless remarks.

The thread thus far had discussed the observer bias /sample size issues and I fully agreed in my first post. A more recent post had then asked the question as to whether our system really is “special” and I put forth an idea, based on what we’ve observed.

And did you have anything of substance to offer to the discussion?
Of course not.
Do you have any ideas of your own as to why our system appears special in the minds of these scientists? And if you do think it may be unique, what then, are some possible scenarios causing the shape of system we see?



But you, you show up playing mouthpiece...

Mouthpiece to whom?? My posts are my opinions.

You’re entitled to your opinions, RAF. And I expect the same respect.

However, I’m tired of the pseudo-skeptical-wannabe-debunker retort every time I have something to say. One can check your posts to verify this, as well as discover that it’s not limited to replies to me.
I suggest that were it not for my post to this thread, you'd have had nothing to say on this topic.



...or "improper posting place police" or something. :roll:
If you have a difficulty with the way I post, PM the BA and complain...if you're unwilling to do that, then stop complaining.

OK, so how about something more insightful, original and/or relevant to the topic for a change, eh?

2005-Apr-04, 06:36 PM
Do you think that Sun-like stars would have planets in position like over here.

With all those billions of stars out-there in the Universe, I must admit, I find it somewhat difficult to imagine that, somewhere, there's no other planet much like ours...There are supposed to be Jovian planets out there - so, why not, Earthlike planets?? :D :D :D :D

Admittedly, we haven't actually found any yet? 8-[ 8-[ 8-[

A.DIM
2005-Apr-04, 06:40 PM
Now, these planets are orbiting single stars? Or are they part of a binary system?

Excellent question.
Binary systems are rather prevalent, again based on what we've observed, are they not?
Oddly enough, this lends itself to the pertur.... ah never mind. :wink:

R.A.F.
2005-Apr-04, 07:19 PM
...how about something more insightful, original and/or relevant to the topic...

Why, sure...

I'll have to go along with "observer bias" on the idea that our Solar System is in some way "special" or "unique". We just haven't studied enough systems to determine a factual baseline of what is, and what isn't "out there". All that can be said is that in all the systems we have observed, there are none that resemble ours. To "jump the gun" and say the our system is "special" is premature...and it will remain that way for the forseeable future.

Maddad
2005-Apr-04, 09:23 PM
But what they discovered were solar systems unlike ours with big Jupiter-like planets close to their host star. Of the 150 alien planets found, none of them resemble our own.Well, duh! Our searching technology is not just biased towards these hot close Jupiters, it is incapable of seeing an Earth-like solar system environment.

Kullat Nunu
2005-Apr-05, 07:54 AM
Astronomy.com: Good news for Goldilocks (http://www.astronomy.com/default.aspx?c=a&id=3040)


Half of the known extrasolar planetary systems could harbor habitable Earths.

A.DIM
2005-Apr-05, 12:29 PM
"Goldilocks:"

He and his colleagues are quick to point out that they did not try to determine if Earth-mass planets actually could form within these stars' habitable zones, but only if they could survive once formed. How readily earthlike planets form, they say, is an urgent question that needs further study.

Avi Mandell, who researches planet formation at Pennsylvania State University, agrees, but still values the current findings. "If their results are robust," he says, "it suggests that our preconceptions of the type of planetary systems that may host habitable or even inhabited planets need to be re-examined."


.... says it all, no?

I mean, not only it is lesser tech but also our "preconceived notions" of what may or may not be possible that muddies these studies. :)

Fram
2005-Apr-05, 12:53 PM
"Goldilocks:"

He and his colleagues are quick to point out that they did not try to determine if Earth-mass planets actually could form within these stars' habitable zones, but only if they could survive once formed. How readily earthlike planets form, they say, is an urgent question that needs further study.

Avi Mandell, who researches planet formation at Pennsylvania State University, agrees, but still values the current findings. "If their results are robust," he says, "it suggests that our preconceptions of the type of planetary systems that may host habitable or even inhabited planets need to be re-examined."


.... says it all, no?

I mean, not only it is lesser tech but also our "preconceived notions" of what may or may not be possible that muddies these studies. :)

So? I don't see your point here.
What I get out of this link is that we aren't so special after all, possibly. So there's no need to sneak your pet theory back in again yet.

A.DIM
2005-Apr-05, 01:43 PM
"Goldilocks:"

He and his colleagues are quick to point out that they did not try to determine if Earth-mass planets actually could form within these stars' habitable zones, but only if they could survive once formed. How readily earthlike planets form, they say, is an urgent question that needs further study.

Avi Mandell, who researches planet formation at Pennsylvania State University, agrees, but still values the current findings. "If their results are robust," he says, "it suggests that our preconceptions of the type of planetary systems that may host habitable or even inhabited planets need to be re-examined."

.... says it all, no?

I mean, not only it is lesser tech but also our "preconceived notions" of what may or may not be possible that muddies these studies. :)

So? I don't see your point here.
What I get out of this link is that we aren't so special after all, possibly. So there's no need to sneak your pet theory back in again yet.

Fram, if I decide to push Sitchin's Nibiru, you'll know it.

Regardless, my point was that an article ago it was suggested that our solar system is "special" adding to the "rare earth" argument, and now we have study that claims "earths" could abound in starkly different cosmic environments than what we thought. Add to the mix our preconceptions of "habitable or inhabited planets" and well... you should get the point now.

So my remark was nothing more than that, a simple opinion acknowledging the point of an article.
To allege "sneaking" in a "pet theory" is highly subjective, you know.

Fram
2005-Apr-05, 02:30 PM
To allege "sneaking" in a "pet theory" is highly subjective, you know.
I know. That doesn't mean it's wrong, of course. And if you start talking about a perturber that is possibly still present, it's hard to see what else you could mean, with your history around here.

A.DIM
2005-Apr-05, 04:55 PM
To allege "sneaking" in a "pet theory" is highly subjective, you know.
I know. That doesn't mean it's wrong, of course. And if you start talking about a perturber that is possibly still present, it's hard to see what else you could mean, with your history around here.

So what you're saying, then, is that given my "history" - eg. I consider the ETH likely and I'm a Sitchinite - you can't help but understand all I have to say as "sneaking" a "pet theory" into everything, right?

Sounds like attacking the person and not the idea - if you ask me - which is not altogether surprising, considering the histories of any number of pseudoskeptics here or elsewhere.

Bottom line: Objectively considering what we are finding and what we know about our solar system lends itself to a perturber scenario being the cause, which as you should know, has even been suggested by various astronomers. Nothing is certain, I admit, but my agreeance with the perturber hypoethesis is not so against-the-mainstream as some would like to think.
It is only because I'm a Sitchinite that I attract such argumentative "debunkers," and at this point, you included.

Fram
2005-Apr-05, 05:30 PM
To allege "sneaking" in a "pet theory" is highly subjective, you know.
I know. That doesn't mean it's wrong, of course. And if you start talking about a perturber that is possibly still present, it's hard to see what else you could mean, with your history around here.

So what you're saying, then, is that given my "history" - eg. I consider the ETH likely and I'm a Sitchinite - you can't help but understand all I have to say as "sneaking" a "pet theory" into everything, right?

Sounds like attacking the person and not the idea - if you ask me - which is not altogether surprising, considering the histories of any number of pseudoskeptics here or elsewhere.

Bottom line: Objectively considering what we are finding and what we know about our solar system lends itself to a perturber scenario being the cause, which as you should know, has even been suggested by various astronomers. Nothing is certain, I admit, but my agreeance with the perturber hypoethesis is not so against-the-mainstream as some would like to think.
It is only because I'm a Sitchinite that I attract such argumentative "debunkers," and at this point, you included.

Not attacking the person, just noticing your habit of almost always starting again about the same thing.
There are perturber hypotheses which are not against-the-mainstream, but your interpretation of it definitely is. Don't try to be an innocent martyr when you aren't. You know that I have tried to have a debtae with you about your arguments, but sadly it turned out to be impossible to have a civilized debate with you. I don't think you are in the right position to complain about ad hominems at all.

kenneth rodman
2005-Apr-05, 06:42 PM
http://cfa-www.harvard.edu/planets/cat1.html

R.A.F.
2005-Apr-06, 12:18 PM
There are perturber hypotheses which are not against-the-mainstream, but your interpretation of it definitely is.

Yep...that's the way I see it, too.

A.DIM
2005-Apr-06, 12:41 PM
There are perturber hypotheses which are not against-the-mainstream, but your interpretation of it definitely is.

Yep...that's the way I see it, too.


OK, but did I say anything about my "interpretation" of the perturber when I first posted? No.

I stated, simply, that a perturber is one scenario that might explain what we see in our system as compared to what we've seen thus far in others.

And not unexpectedly both of you were quick to infer "my" interpretation of the perturber hypothesis. Is this not attacking the person rather than the idea at hand? I mean, here we have both of you acknowledging there are mainstream perturber hyptheses, and yet, when I suggest as much, making no reference to Sitchin or Nibiru, both allege "sneaky pet theories" and other such tripe.
:-?

R.A.F.
2005-Apr-06, 12:51 PM
A.DIM...are Fram and I to be "faulted", because we recall your previous posts? Perhaps if you had stated from the onset that you were not talking about Sitchin's Nuburu, this whole mess could have been avoided.

Fram
2005-Apr-06, 01:35 PM
There are perturber hypotheses which are not against-the-mainstream, but your interpretation of it definitely is.

Yep...that's the way I see it, too.


OK, but did I say anything about my "interpretation" of the perturber when I first posted? No.

I stated, simply, that a perturber is one scenario that might explain what we see in our system as compared to what we've seen thus far in others.

And not unexpectedly both of you were quick to infer "my" interpretation of the perturber hypothesis. Is this not attacking the person rather than the idea at hand? I mean, here we have both of you acknowledging there are mainstream perturber hyptheses, and yet, when I suggest as much, making no reference to Sitchin or Nibiru, both allege "sneaky pet theories" and other such tripe.
:-?
Well, I don't think the 'possibly still present' perturber is a mainstream theory at all. The once in a very distant past perturber can be called 'alternative' mainstream, but you'll be hard pressed to find many people who will call a still present perturber mainstream. And that is what you said in your first post here. Or do you know of other ones besides the Sitchin one that are more accepted?

A.DIM
2005-Apr-06, 09:29 PM
A.DIM...are Fram and I to be "faulted", because we recall your previous posts? Perhaps if you had stated from the onset that you were not talking about Sitchin's Nuburu, this whole mess could have been avoided.

RAF, you'll know when I talk about Sitchin's Nibiru; I'll be very explicit, I assure you.

But this "mess" would've been avoided had you, or Fram, not subjectively inferred some "sneaky pet theory" to begin with.

A.DIM
2005-Apr-06, 09:33 PM
There are perturber hypotheses which are not against-the-mainstream, but your interpretation of it definitely is.

Yep...that's the way I see it, too.


OK, but did I say anything about my "interpretation" of the perturber when I first posted? No.

I stated, simply, that a perturber is one scenario that might explain what we see in our system as compared to what we've seen thus far in others.

And not unexpectedly both of you were quick to infer "my" interpretation of the perturber hypothesis. Is this not attacking the person rather than the idea at hand? I mean, here we have both of you acknowledging there are mainstream perturber hyptheses, and yet, when I suggest as much, making no reference to Sitchin or Nibiru, both allege "sneaky pet theories" and other such tripe.
:-?
Well, I don't think the 'possibly still present' perturber is a mainstream theory at all. The once in a very distant past perturber can be called 'alternative' mainstream, but you'll be hard pressed to find many people who will call a still present perturber mainstream. And that is what you said in your first post here. Or do you know of other ones besides the Sitchin one that are more accepted?

Mike Brown, discoverer of Sedna, suggested "still present." Dr's Murray and Matese have suggested "still present." I think even Marsden, too, suggested it.
But you're right, it isn't necessarily mainstream. We're only now beginning to acknowledge the very real possibility of the perturber hypothesis.

I suggest it shan't be long now before it is discovered.

Fram
2005-Apr-07, 07:28 AM
Well, I don't think the 'possibly still present' perturber is a mainstream theory at all. The once in a very distant past perturber can be called 'alternative' mainstream, but you'll be hard pressed to find many people who will call a still present perturber mainstream. And that is what you said in your first post here. Or do you know of other ones besides the Sitchin one that are more accepted?

Mike Brown, discoverer of Sedna, suggested "still present." Dr's Murray and Matese have suggested "still present." I think even Marsden, too, suggested it.
But you're right, it isn't necessarily mainstream. We're only now beginning to acknowledge the very real possibility of the perturber hypothesis.

I suggest it shan't be long now before it is discovered.

I've searched for Mike Brown's comments on Sedna (http://www.gps.caltech.edu/~mbrown/sedna/), and what I can found here, is that there are two current theories: a passing star (so not 'still present'), or a present planet.


There are some KBOs that go very far from the sun like Sedna does, but they all have closest approach at about 35-45 AU. Sedna is special because it doesn't come any closer than 75 AU to the sun. We believe that this is because of the effects of passing stars, as described above.

A second speculative explanation for Sedna's orbit is that a larger body, perhaps Mars-sized or larger could exist at around 70 AU in a circular orbit and could have caused Sedna to get thrown into its strange orbit. If such a planet existed, we would likely have already found it in our survey, though there are still a few places left to hide.

You'll notice that from the way he formulates this, he doesn't believe or suggest a still present perturber, but that he can not rule out the possibility completely. But you'll also notice that the perturber he describes has a quasi circular orbit at 70 AU, so that it can hardly be held responsible for more perturbations of the solar system (remember, the question was why we had quasi circular orbits in the first place). So I don't think you can use Mike Brown to defend your position.
I'll not search for your other names, I have found too often that your links or sources don't support what you claim they do and I have wasted too much time on those in the past. If you have a more precise source, please feel free to post it, and I'll look at it. For now, my opinion of you has only been confirmed...

dvb
2005-Apr-07, 08:51 AM
Did any of you actually read the article?


“I have a problem referring to our own solar system as unusual, because we haven’t done that experiment yet, we haven’t searched for our own solar system yet,” said Turnbull Thus far, the kind of data obtained and the type of observations made are tuned to search for Jupiters and not Earths, therefore that’s what we find. “The experiments were designed for that,” she explained.

But with the vast majority of the alien planets found in eccentric orbits, Butler has a different view. “I think with the data at hand, we can say that our solar system is rare. Eccentricity dominates,” said Butler. “It’s just a matter of how rare we are,” he added.

No one claims that lack of observed Earth-size planets makes our solar system special. That would be asinine, for it is entirely Observer Bias. The point of the article is that if you exclude "hot Jupiters" (prevalence of which is also Observer Bias), then almost all extrasolar planets are in eccentric orbits. That is not Observer Bias, is definitely different from Solar System, and does not bode well for terrestrial planets (other than moons of giant planets).

I still see it as observer bias. The reason that we're detecting large planets with eccentric orbits, is because they cause the star to wobble more, thus making it easier to detect with todays equipment. That's my take on it anyways.

eccentric orbit + large planet = greater wobble = easier detection

What I wonder is, if it's even physically possible for a rocky planet to be 15x the mass of Earth. I would imagine most of it to be made up of molten liquid due to the immense gravity. Might be a whole new class of planet. Not really solid rock, or gaseous.

eburacum45
2005-Apr-07, 10:08 AM
Well, a sample planet with a mass 15 times Earth could have a density of 6500 kg/m³ compared to Earth's 5500 kg/m³ (this is just a guesstimate- compression might make the density and hence the gravity even higher); it would have a diameter of 29000 km compared to Earth's 12700 km and a gravity of 2.7g.

With such a high gravity it would retain hydrogen in the atmosphere even in the habitable zone- so it would be a small to middle-sized, warm, gas giant.

So you are right- no giant rocky terrestrials are possible in the habitable zone.

JohnD
2005-Apr-07, 10:29 AM
Rather than a special solar system, could it be that the Earth-Moon system is special? No other planet has such a relatively large satellite, which may explain the extreme difference of Venus.
John

A.DIM
2005-Apr-07, 11:57 AM
Well, I don't think the 'possibly still present' perturber is a mainstream theory at all. The once in a very distant past perturber can be called 'alternative' mainstream, but you'll be hard pressed to find many people who will call a still present perturber mainstream. And that is what you said in your first post here. Or do you know of other ones besides the Sitchin one that are more accepted?

Mike Brown, discoverer of Sedna, suggested "still present." Dr's Murray and Matese have suggested "still present." I think even Marsden, too, suggested it.
But you're right, it isn't necessarily mainstream. We're only now beginning to acknowledge the very real possibility of the perturber hypothesis.

I suggest it shan't be long now before it is discovered.

I've searched for Mike Brown's comments on Sedna (http://www.gps.caltech.edu/~mbrown/sedna/), and what I can found here, is that there are two current theories: a passing star (so not 'still present'), or a present planet.


There are some KBOs that go very far from the sun like Sedna does, but they all have closest approach at about 35-45 AU. Sedna is special because it doesn't come any closer than 75 AU to the sun. We believe that this is because of the effects of passing stars, as described above.

A second speculative explanation for Sedna's orbit is that a larger body, perhaps Mars-sized or larger could exist at around 70 AU in a circular orbit and could have caused Sedna to get thrown into its strange orbit. If such a planet existed, we would likely have already found it in our survey, though there are still a few places left to hide.

You'll notice that from the way he formulates this, he doesn't believe or suggest a still present perturber, but that he can not rule out the possibility completely. But you'll also notice that the perturber he describes has a quasi circular orbit at 70 AU, so that it can hardly be held responsible for more perturbations of the solar system (remember, the question was why we had quasi circular orbits in the first place). So I don't think you can use Mike Brown to defend your position.
I'll not search for your other names, I have found too often that your links or sources don't support what you claim they do and I have wasted too much time on those in the past. If you have a more precise source, please feel free to post it, and I'll look at it. For now, my opinion of you has only been confirmed...

Terrific, so why waste your time arguing with me?

If you are so convinced that I am wrong, why waste your time debating anything with me? If my ideas are so outlandish, surely no one here reading my posts will be swayed. So what is your point then?

A.DIM
2005-Apr-07, 12:04 PM
Rather than a special solar system, could it be that the Earth-Moon system is special? No other planet has such a relatively large satellite, which may explain the extreme difference of Venus.
John

I agree, the Earth/Moon system is a puzzle.
In my opinion, the Pacific Basin is the cavity left from the celestial collision that resulted in the formation of the moon, some comets, and the asteroid belt.

Fram
2005-Apr-07, 12:14 PM
Well, I don't think the 'possibly still present' perturber is a mainstream theory at all. The once in a very distant past perturber can be called 'alternative' mainstream, but you'll be hard pressed to find many people who will call a still present perturber mainstream. And that is what you said in your first post here. Or do you know of other ones besides the Sitchin one that are more accepted?

Mike Brown, discoverer of Sedna, suggested "still present." Dr's Murray and Matese have suggested "still present." I think even Marsden, too, suggested it.
But you're right, it isn't necessarily mainstream. We're only now beginning to acknowledge the very real possibility of the perturber hypothesis.

I suggest it shan't be long now before it is discovered.

I've searched for Mike Brown's comments on Sedna (http://www.gps.caltech.edu/~mbrown/sedna/), and what I can found here, is that there are two current theories: a passing star (so not 'still present'), or a present planet.


There are some KBOs that go very far from the sun like Sedna does, but they all have closest approach at about 35-45 AU. Sedna is special because it doesn't come any closer than 75 AU to the sun. We believe that this is because of the effects of passing stars, as described above.

A second speculative explanation for Sedna's orbit is that a larger body, perhaps Mars-sized or larger could exist at around 70 AU in a circular orbit and could have caused Sedna to get thrown into its strange orbit. If such a planet existed, we would likely have already found it in our survey, though there are still a few places left to hide.

You'll notice that from the way he formulates this, he doesn't believe or suggest a still present perturber, but that he can not rule out the possibility completely. But you'll also notice that the perturber he describes has a quasi circular orbit at 70 AU, so that it can hardly be held responsible for more perturbations of the solar system (remember, the question was why we had quasi circular orbits in the first place). So I don't think you can use Mike Brown to defend your position.
I'll not search for your other names, I have found too often that your links or sources don't support what you claim they do and I have wasted too much time on those in the past. If you have a more precise source, please feel free to post it, and I'll look at it. For now, my opinion of you has only been confirmed...

Terrific, so why waste your time arguing with me?

If you are so convinced that I am wrong, why waste your time debating anything with me? If my ideas are so outlandish, surely no one here reading my posts will be swayed. So what is your point then?
My point is that you are wrong, that you keep on posting nonetheless, and that when you are shown to be wrong (as here), you ignore that and start ranting.
With your first post, people without prior knowledge of you and your ideas had no way of judging it. Now, you have been forced to give some credibility, some sources to your ideas, and you failed (again).
Now, indeed, the chance is smaller that people here will be swayed by your outlandish ideas (of which we have only skimmed the surface, luckily), although I'll never cease to be amazed what people are willing to believe (like Lyndon Ashmore and his astrology).

R.A.F.
2005-Apr-07, 12:21 PM
If my ideas are so outlandish, surely no one here reading my posts will be swayed.

You sell yourself "short", A.DIM...you are a skilled debater, and there might be someone lurking here that thinks your ideas have merit. Fram and I (and others like us) are simply here to make sure you are honest and prove your ideas.

Fram
2005-Apr-07, 12:22 PM
Rather than a special solar system, could it be that the Earth-Moon system is special? No other planet has such a relatively large satellite, which may explain the extreme difference of Venus.
John

I agree, the Earth/Moon system is a puzzle.
In my opinion, the Pacific Basin is the cavity left from the celestial collision that resulted in the formation of the moon, some comets, and the asteroid belt.

Any reason why the asteroid belt is mainly situated between Mars and Jupiter, and not between Earth and Mars?
And any explanation why and how comets would have been created this way?

A.DIM
2005-Apr-07, 12:39 PM
Terrific, so why waste your time arguing with me?

If you are so convinced that I am wrong, why waste your time debating anything with me? If my ideas are so outlandish, surely no one here reading my posts will be swayed. So what is your point then?
My point is that you are wrong, that you keep on posting nonetheless, and that when you are shown to be wrong (as here), you ignore that and start ranting.

But you've certainly not shown me to be wrong here, Fram. How can I be when we know so little about what is actually out there, and confecture is really all we have?

My opinion on this issue is based on what other astronomers have stated themselves:
Distant Sedna Raises Possibility of Another Earth-Sized Planet in Our Solar System (http://www.space.com/scienceastronomy/sedna_earth_040316.html):

"How on Earth could anything get into an orbit like that," wonders astronomer Brian Marsden. He suggests another sort of Earth might have had something to do with putting Sedna on its current, odd course."

"Marsden favors an object closer in, a "planetary object," he told SPACE.com , perhaps at between 400 and 1,000 AU.

"Perhaps there's more than one planet out there," Marsden said. "Who knows? But let's suppose it is something of an Earth mass, maybe even a few Earth masses. A close approach could throw this object [Sedna] from something more circular into something more eccentric."


With your first post, people without prior knowledge of you and your ideas had no way of judging it. Now, you have been forced to give some credibility, some sources to your ideas, and you failed (again).
Now, indeed, the chance is smaller that people here will be swayed by your outlandish ideas (of which we have only skimmed the surface, luckily), although I'll never cease to be amazed what people are willing to believe (like Lyndon Ashmore and his astrology).

People without knowledge of me and my ideas could read my first post and make up their own minds on the "special" solar system and perturber hypotheses, no "background" knowledge was needed.

What really confounds me most about all this is if something validates my ideas in my own mind, what does it matter to you?

A.DIM
2005-Apr-07, 12:43 PM
If my ideas are so outlandish, surely no one here reading my posts will be swayed.

You sell yourself "short", A.DIM...you are a skilled debater, and there might be someone lurking here that thinks your ideas have merit. Fram and I (and others like us) are simply here to make sure you are honest and prove your ideas.

Why, thanks, RAF, but on this issue, nothing can be "proven" yet and so there should be no reason for us to argue.
Do you not agree?

Fram
2005-Apr-07, 12:57 PM
Terrific, so why waste your time arguing with me?

If you are so convinced that I am wrong, why waste your time debating anything with me? If my ideas are so outlandish, surely no one here reading my posts will be swayed. So what is your point then?
My point is that you are wrong, that you keep on posting nonetheless, and that when you are shown to be wrong (as here), you ignore that and start ranting.

But you've certainly not shown me to be wrong here, Fram. How can I be when we know so little about what is actually out there, and confecture is really all we have?

I have shown you to be wrong. You said that Mike Brown suggested a still present perturber. I have shown you that he did not, and the link you give now says the same. But at least you try to back up one of the other names you gave now. Sadly he explains (again) why perhaps a perturber has caused a circular orbit to become eccentric, and not the opposite.



People without knowledge of me and my ideas could read my first post and make up their own minds on the "special" solar system and perturber hypotheses, no "background" knowledge was needed.

What really confounds me most about all this is if something validates my ideas in my own mind, what does it matter to you?

If the ideas in your mind start showing up on the screen of my computer, explicitly or implicitly, then it does matter to me. If you can't stand criticism of your ideas, don't post them here.

A.DIM
2005-Apr-07, 01:19 PM
Terrific, so why waste your time arguing with me?

If you are so convinced that I am wrong, why waste your time debating anything with me? If my ideas are so outlandish, surely no one here reading my posts will be swayed. So what is your point then?
My point is that you are wrong, that you keep on posting nonetheless, and that when you are shown to be wrong (as here), you ignore that and start ranting.

But you've certainly not shown me to be wrong here, Fram. How can I be when we know so little about what is actually out there, and confecture is really all we have?

I have shown you to be wrong. You said that Mike Brown suggested a still present perturber. I have shown you that he did not, and the link you give now says the same. But at least you try to back up one of the other names you gave now. Sadly he explains (again) why perhaps a perturber has caused a circular orbit to become eccentric, and not the opposite.

Did you read the paper Brown published in ApJ Letters?

His first suggestion was a single planetary body, "as yet undiscovered," as being the cause. Did you miss that?
So, in fact, you DID NOT show me to be wrong.
But I must agree, of the 3 scenarios presented, all predict a much larger population of bodies in the "inner Oort Cloud."
And whatever the scenario, the perturber hypothesis still remains valid.




People without knowledge of me and my ideas could read my first post and make up their own minds on the "special" solar system and perturber hypotheses, no "background" knowledge was needed.

What really confounds me most about all this is if something validates my ideas in my own mind, what does it matter to you?

If the ideas in your mind start showing up on the screen of my computer, explicitly or implicitly, then it does matter to me. If you can't stand criticism of your ideas, don't post them here.

I don't mind being criticized, Fram; you're most welcome to it, so long as you have a fairly solid basis for doing so.
Which has not been the case in this thread.

Fram
2005-Apr-07, 01:28 PM
Terrific, so why waste your time arguing with me?

If you are so convinced that I am wrong, why waste your time debating anything with me? If my ideas are so outlandish, surely no one here reading my posts will be swayed. So what is your point then?
My point is that you are wrong, that you keep on posting nonetheless, and that when you are shown to be wrong (as here), you ignore that and start ranting.

But you've certainly not shown me to be wrong here, Fram. How can I be when we know so little about what is actually out there, and confecture is really all we have?

I have shown you to be wrong. You said that Mike Brown suggested a still present perturber. I have shown you that he did not, and the link you give now says the same. But at least you try to back up one of the other names you gave now. Sadly he explains (again) why perhaps a perturber has caused a circular orbit to become eccentric, and not the opposite.

Did you read the paper Brown published in ApJ Letters?

His first suggestion was a single planetary body, "as yet undiscovered," as being the cause. Did you miss that?
So, in fact, you DID NOT show me to be wrong.
But I must agree, of the 3 scenarios presented, all predict a much larger population of bodies in the "inner Oort Cloud."
And whatever the scenario, the perturber hypothesis still remains valid.

No, I have not read that paper. But both the link to space.com you provided, and to his own webpage (that I provided), disagree. So while I don't know what he said in that paper, I know that in at least two instances, one of them representing his current stance on it (his webpage), he has acknowledged the suggestion of a planetary body, and then dismissed it as being highly improbable. In the ApJ paper, did he propose it as his suggestion of choice, or as a suggestion he didn't agree with? And did he propose there as well that a passing star was the cause he preferred? If the latter, then you are quite disingenious. Otherwise, he is a very fickle one and he should make up his mind.
And what 'perturber hypothesis' still remains valid? Yours / Sitchins, or one of the hypotheses concerning Sedna? There is no 'THE perturber hypothesis', there's a whole range of them.

Fram
2005-Apr-07, 01:38 PM
After searching a bit, I have found the ApJ paper A.DIM referred to, and surprise, surprise, what does it have to say about the planetary perturber:

We therefore deem the existence of such a scattering planet unlikely, but we are unable to rule the possibility out completely.
So, as I expected, it was his first suggestion, and he dismissed it. How convenient that you left the second part out, A.DIM. [-X

EDIT: for those interested, it is the first reference at the bottom of this page (http://www.answers.com/topic/90377-sedna): it's a thirteen page pdf.

JohnD
2005-Apr-07, 02:36 PM
Fram & Dim have so monopolised this thread that I am forced to resort to quotes:

JohnD wrote:
Rather than a special solar system, could it be that the Earth-Moon system is special? No other planet has such a relatively large satellite, which may explain the extreme difference of Venus.
John
Dim wrote:
I agree, the Earth/Moon system is a puzzle.
In my opinion [Note, no humble - Ed], the Pacific Basin is the cavity left from the celestial collision that resulted in the formation of the moon, some comets, and the asteroid belt.

Now:
Oh, come on, Dim. Be serious.
What about tectonics??? If Gondwanaland existed then was the rest of the water covered Earth the cavity? It's all moved about a bit since then.

John

A.DIM
2005-Apr-07, 03:01 PM
After searching a bit, I have found the ApJ paper A.DIM referred to, and surprise, surprise, what does it have to say about the planetary perturber:

We therefore deem the existence of such a scattering planet unlikely, but we are unable to rule the possibility out completely.
So, as I expected, it was his first suggestion, and he dismissed it. How convenient that you left the second part out, A.DIM. [-X
EDIT: for those interested, it is the first reference at the bottom of this page (http://www.answers.com/topic/90377-sedna): it's a thirteen page pdf.

OK, but the "discussion" part at the end of the ApJ paper says this:

" Each of the plausible scenarios for the origin of the distant object predicts a specific dynamical population beyond the Kuiper Belt. With only a single object, though, little dynamical evidence exists for preferring any one scenario. With any new discoveries in this region, however, evidence should quickly mount."

So, as I said, among the 3 plausible scenarios put forth, none of them negate a perturber hypothesis, Fram. Brown did not "dismiss" it as you say. In another article he says the same thing: "... we deem it unlikely because we think we would have found it by now."

That's why he says "we can't rule out the possibility." More sky within the ecliptic as well as above and below it need to be explored.




edited to fix quotes.

A.DIM
2005-Apr-07, 03:09 PM
Fram & Dim have so monopolised this thread that I am forced to resort to quotes:

JohnD wrote:
Rather than a special solar system, could it be that the Earth-Moon system is special? No other planet has such a relatively large satellite, which may explain the extreme difference of Venus.
John
Dim wrote:
I agree, the Earth/Moon system is a puzzle.
In my opinion [Note, no humble - Ed], the Pacific Basin is the cavity left from the celestial collision that resulted in the formation of the moon, some comets, and the asteroid belt.

Now:
Oh, come on, Dim. Be serious.
What about tectonics??? If Gondwanaland existed then was the rest of the water covered Earth the cavity? It's all moved about a bit since then.

John

Good question, John.
Curiously enough, when one puts the pieces of Pangaea together, the landmass is opposite the pacific basin. Is it possible that after the celestial collision the earth began to "heal" itself, almost as if a "scab" through tectonics pushing and pulling landmasses toward the pacific?

Fram
2005-Apr-07, 03:14 PM
After searching a bit, I have found the ApJ paper A.DIM referred to, and surprise, surprise, what does it have to say about the planetary perturber:

We therefore deem the existence of such a scattering planet unlikely, but we are unable to rule the possibility out completely.
So, as I expected, it was his first suggestion, and he dismissed it. How convenient that you left the second part out, A.DIM. [-X
EDIT: for those interested, it is the first reference at the bottom of this page (http://www.answers.com/topic/90377-sedna): it's a thirteen page pdf.

OK, but the "discussion" part at the end of the ApJ paper says this:

" Each of the plausible scenarios for the origin of the distant object predicts a specific dynamical population beyond the Kuiper Belt. With only a single object, though, little dynamical evidence exists for preferring any one scenario. With any new discoveries in this region, however, evidence should quickly mount."

So, as I said, among the 3 plausible scenarios put forth, none of them negate a perturber hypothesis, Fram. Brown did not "dismiss" it as you say. In another article he says the same thing: "... we deem it unlikely because we think we would have found it by now."

That's why he says "we can't rule out the possibility." More sky within the ecliptic as well as above and below it need to be explored.

But you said he suggested it, without saying that he deemed it unlikely. You gave the impression that it was his idea, his primary hypothesis, which it isn't at all.
And then you still have the rather basic problem that the hypotheses they are talking about all have the opposite effect of what you are looking for: they create an eccentric orbit, what you need is a circular orbit.

A.DIM
2005-Apr-08, 04:17 PM
After searching a bit, I have found the ApJ paper A.DIM referred to, and surprise, surprise, what does it have to say about the planetary perturber:

We therefore deem the existence of such a scattering planet unlikely, but we are unable to rule the possibility out completely.
So, as I expected, it was his first suggestion, and he dismissed it. How convenient that you left the second part out, A.DIM. [-X
EDIT: for those interested, it is the first reference at the bottom of this page (http://www.answers.com/topic/90377-sedna): it's a thirteen page pdf.

OK, but the "discussion" part at the end of the ApJ paper says this:

" Each of the plausible scenarios for the origin of the distant object predicts a specific dynamical population beyond the Kuiper Belt. With only a single object, though, little dynamical evidence exists for preferring any one scenario. With any new discoveries in this region, however, evidence should quickly mount."

So, as I said, among the 3 plausible scenarios put forth, none of them negate a perturber hypothesis, Fram. Brown did not "dismiss" it as you say. In another article he says the same thing: "... we deem it unlikely because we think we would have found it by now."

That's why he says "we can't rule out the possibility." More sky within the ecliptic as well as above and below it need to be explored.

But you said he suggested it, without saying that he deemed it unlikely. You gave the impression that it was his idea, his primary hypothesis, which it isn't at all.
And then you still have the rather basic problem that the hypotheses they are talking about all have the opposite effect of what you are looking for: they create an eccentric orbit, what you need is a circular orbit.


Your post here allows us to come full circle, Fram.
(pun intended) :)


Yes, this discussion is (was) about the "special" nature of our solar system's circular orbiting bodies, and a perturber hypothesis is mostly based on the elliptical orbits we're seeing in other bodies. In my initial post I merely opined a perturber hypothesis as possibly causing the seemingly special nature of our system. And what I had in mind was that such a perturber could be in a sort of resonant orbit with the planets, giving them their quasi-circular paths.
BUT, what happened was I ultimately had to defend the idea that a perturber hypothesis even exists! Not to mention having to field all the accusations of "sneaky pet theories." But I did so by pointing out Brown, Marsden, Murray, Matese et al. And I'm rather certain that I acknowledged first: more data is needed; and second: of the 3 scenarios put forth, whichever is discovered to be factual, none of them negate a perturber hypothesis.

Again, more observations are needed before any certainty arises, and so ultimately all we have is opinion; but definitely no reason to argue and allege ulterior motives, that's for certain.

Maddad
2005-Apr-11, 10:46 PM
What I wonder is, if it's even physically possible for a rocky planet to be 15x the mass of Earth. I would imagine most of it to be made up of molten liquid due to the immense gravity.Gravity does not directly equate with heat. However, with 15 times the mass, you have several times the surface area. Less than 4 times, the approximate square root of 15, but less because the gravity would compress the rock to a greater density. Pull a number out of the air and say three times the surface area as Earth. The radiative heat loss would be a fifth as much as Earth, so it would stay hotter and be volcanically and geologically active longer.


With such a high gravity it would retain hydrogen in the atmosphere even in the habitable zone- so it would be a small to middle-sized, warm, gas giant.It should retain far more water as well, so once you got below the gas envelop, you might find a water world.

But as for the question of whether our planet is special, I say it's pretty special to us.

zimbel42
2005-Apr-12, 10:08 PM
Good question, John.
Curiously enough, when one puts the pieces of Pangaea together, the landmass is opposite the pacific basin. Is it possible that after the celestial collision the earth began to "heal" itself, almost as if a "scab" through tectonics pushing and pulling landmasses toward the pacific?

I don't think you've looked at the math on this one. If you're curious, there are plenty of comet and asteroid impact calculators on the web, although few (if any) will be accurate for this level of energy.

In the event that a moon-sized object came from the earth, the collision producing this seperation would give an impact "crater" far far deeper than the Earth's entire crust, never mind the minimal depth of the Pacific Ocean. All the water would be vaporized; the term "ocean" would not have a meaning. Ejecta would cover the remaining body of mass. You would have little or no rock in a solid phase. The matter of the "Earth" would no longer be even close to spherical in its distribution.

Cooling a crust into a solid phase on the mass we now call the "Earth" would take extremely long periods of time. I suspect that minor recent perturbations in the Earth's crust (like the pacific basin) have to do with far more recent events.

Note that I am not arguing whether or not the moon came from a highly energetic collision with a pre-Earth body of matter; I am merely stating that if it did, any "scarring" that occurred at the time would no longer be noticable.

Out of curiosity, is there any credible evidence suggesting such a collision?

A.DIM
2005-Apr-22, 04:59 PM
Good question, John.
Curiously enough, when one puts the pieces of Pangaea together, the landmass is opposite the pacific basin. Is it possible that after the celestial collision the earth began to "heal" itself, almost as if a "scab" through tectonics pushing and pulling landmasses toward the pacific?

I don't think you've looked at the math on this one. If you're curious, there are plenty of comet and asteroid impact calculators on the web, although few (if any) will be accurate for this level of energy.

In the event that a moon-sized object came from the earth, the collision producing this seperation would give an impact "crater" far far deeper than the Earth's entire crust, never mind the minimal depth of the Pacific Ocean. All the water would be vaporized; the term "ocean" would not have a meaning. Ejecta would cover the remaining body of mass. You would have little or no rock in a solid phase. The matter of the "Earth" would no longer be even close to spherical in its distribution.

Cooling a crust into a solid phase on the mass we now call the "Earth" would take extremely long periods of time. I suspect that minor recent perturbations in the Earth's crust (like the pacific basin) have to do with far more recent events.

Note that I am not arguing whether or not the moon came from a highly energetic collision with a pre-Earth body of matter; I am merely stating that if it did, any "scarring" that occurred at the time would no longer be noticable.

Out of curiosity, is there any credible evidence suggesting such a collision?

Does Cosmic Catastrophes (http://www.tufts.edu/as/wright_center/cosmic_evolution/docs/text/text_plan_2.html) qualify?

I actually think the moon is older than the celestial collision I referred to, and was itself bombarded to death by the debris.

I've not done the math personally, but from what I read on the subject, no one's math is quite working. From the link:

"A third idea maintains that the Moon materialized out of Earth itself. The Pacific Basin has often been mentioned as the place from which protolunar matter might have been torn, the result of centrifugal forces on a young, molten, and rapidly rotating Earth. As absurd as this idea may seem, the early findings of the Apollo Program seemed to favor it. Both the lunar composition and density were found to mimic those of Earth’s mantle, that region just below the crust. However, recent, more exacting studies of our Moon’s makeup show significant dissimilarities to Earth’s underbelly. What’s more, there remains the fundamental mystery of how the Earth could possibly have ejected into a stable orbit an object as large as the Moon.

Clearly, none of these theories is compelling. Each suffers from a major flaw or two. Yet, it would seem that one of them, or some version of them, must be correct. In fact, astronomers now favor a hybrid model combining the best features of each of the above ideas. The most popular model today postulates a vast, ancient collision between a young, molten Earth and a large, Mars-sized object. Impacts were undoubtedly common in the early Solar System, although one of this magnitude would have been nearly catastrophic; perhaps it was more of a glancing blow than a head-on collision. Matter dislodged from our planet, as well as parts of the impacting object itself, presumably then aggregated to form the Moon. Computer simulations do show that, for a collision at an oblique angle, debris having largely the composition of Earth’s mantle could have been ejected into a stable orbit nearly halfway to where the Moon resides today. It probably would have happened quickly, with the far-flung material reassembling into a single clump within a few weeks and forming a spherical rock resembling today’s Moon within a year."

John Dlugosz
2005-Apr-23, 04:00 AM
The Pacific Basin has often been mentioned as the place from which protolunar matter might have been torn, the result of centrifugal forces on a young, molten, and rapidly rotating Earth.

What Pacific Basin? The world didn't start with Pangea--that was meerly the most recient configuration. All the continants moved around to form it, and before that there was no Pacific and all the land was on the other side! It's come together into a big mass at least 3 times, if memory serves. The entire tectonic plate has been subducted and renewed in-toto several times.

IAC, the depth of the ocean doesn't qualify as a divit on this scale. The earch is smoother than a billiard ball.

--John

Kullat Nunu
2005-Apr-23, 01:30 PM
The Pacific Basin has often been mentioned as the place from which protolunar matter might have been torn, the result of centrifugal forces on a young, molten, and rapidly rotating Earth.

What Pacific Basin? The world didn't start with Pangea--that was meerly the most recient configuration. All the continants moved around to form it, and before that there was no Pacific and all the land was on the other side! It's come together into a big mass at least 3 times, if memory serves. The entire tectonic plate has been subducted and renewed in-toto several times.

IAC, the depth of the ocean doesn't qualify as a divit on this scale. The earch is smoother than a billiard ball.

--John

Pangaea, Pannotia, Rodinia, Columbia, Kenorland, Ur, ... There are several theorized supercontinents, of which Pangaea and Rodinia should be well-established.

That Moon splitted from the Pacific Ocean theory predates the discovery of plate tectonics.

A.DIM
2005-Apr-25, 05:08 PM
The Pacific Basin has often been mentioned as the place from which protolunar matter might have been torn, the result of centrifugal forces on a young, molten, and rapidly rotating Earth.

What Pacific Basin? The world didn't start with Pangea--that was meerly the most recient configuration. All the continants moved around to form it, and before that there was no Pacific and all the land was on the other side! It's come together into a big mass at least 3 times, if memory serves. The entire tectonic plate has been subducted and renewed in-toto several times.

The most notable(active?) subduction zones are the "ring of fire," aka the pacific plate or pacific basin.

I agree that there have been at least 2, perhaps 3, supercontinents, but I suspect they were made up of the same landmasses recolliding each time, and still opposite the pacific basin.


IAC, the depth of the ocean doesn't qualify as a divit on this scale. The earch is smoother than a billiard ball.

Yes, I know this argument, but the fact remains that Earth / Moon formation theories suggest, at least, a glancing blow from another planetary body as being a factor, and the pacific basin, IMHO, appears to be that very "wound."

Only last August did NewScientist publish an article called "The Planet That Stalked The Earth" dealing with the event.

Cool stuff, I say.

A.DIM
2005-Apr-25, 05:13 PM
Pangaea, Pannotia, Rodinia, Columbia, Kenorland, Ur, ... There are several theorized supercontinents, of which Pangaea and Rodinia should be well-established.

Agreed. I allow for 2, maybe 3; otherwise, the evidence is rather scant.


That Moon splitted from the Pacific Ocean theory predates the discovery of plate tectonics.

Agreed, but as I said, I suspect the moon was forming long before the collisional event that left it lifeless and mother earth with a chunk ripped out of her side.

jleslie48
2005-Apr-26, 05:56 PM
this discussion has seemed to stray around a bit, I have specific question that does not seem to be addressed, if someone[s] care to enlighten me on:

this article:

http://www.spaceflightnow.com/news/n0504/19orbits/

it goes on to suggest that since the 160 or so planets around stars that have been identified so far have very elliptical orbits, that our solar system is unusual having planets basically in circular stable orbits.

But isn't this article a bit of a self-fullfilling theory? I mean that
the whole reason these planets were discovered is because of the wobble effected on the star by the orbiting planets. Now for my question, isn't the wobble on the star far more pronounced because of the eliptical orbit as compared to the effect on a star of a planet in a circular orbit? Furthermore given a star like ours with multiple jovian planets, all in a plane all in basically circular orbits with different periods, wouldn't the wobble be almost canceled out by the interaction of the various forces of gravity of the different planets?

the_shaggy_one
2005-Apr-26, 09:28 PM
Pangaea, Pannotia, Rodinia, Columbia, Kenorland, Ur, ... There are several theorized supercontinents, of which Pangaea and Rodinia should be well-established.

Agreed. I allow for 2, maybe 3; otherwise, the evidence is rather scant.


That Moon splitted from the Pacific Ocean theory predates the discovery of plate tectonics.

Agreed, but as I said, I suspect the moon was forming long before the collisional event that left it lifeless and mother earth with a chunk ripped out of her side.

The best theory of the moon's formation is that a mars-sized body struck the young Earth at a reatively low angle, which caused a ring of debris to be thrown into orbit. That debris (from both Earth and the mars-sized body) collected and became the moon. An impact of that magnitude would have caused the entire crust to melt and reform (if it had even solidified at the time of the collision), which makes it completely impossible for the pacific basin to be the crater left by that impact.

Here (http://en.wikipedia.org/wiki/Giant_Impact_theory) is a much better explanation, from wikipedia.

Getting back on topic, the wikipedia article also talks about how the formation of the moon may have been condusive to life on earth, by removing enough of the lighter, felsic rock types to allow continents, plate tectonics, and the carbon cycle that makes life possible hear on Earth. There is a link to an article about the possibility that the mar-sized planetesimal formed in the one of the Langrange points, making this sort of impact much more probable in young solar systems. We know of two signifigant objects in our solar system that have a large sattelite-to-primary ratio: Earth/Moon and Pluto/Charon. If true, this makes it much more likely we will find planets very similar to Earth.