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Eulalio

Short period comets and Planet X

17 posts in this topic

According to scientists, comets are leftover debris from the formation of the solar system 4.6 billion years ago, when the solar nebula condensed, and are thought to consist mostly of ice, dust and rock. This means that comets are supposedly as old as our solar system.

Short period comets are comets with orbital periods less than 200 years. They are believed to originate in a region of our solar system known as the Kuiper Belt, which lies just beyond the orbit of Neptune.

Short period comets are thrown (or nudged) from these outer reaches of the Solar System towards the Sun by gravitational perturbations from the outer planets (i.e., Jupiter, Saturn, Uranus, Neptune) or as a result of collisions between objects within this region.

Each time a comet, which is akin to a dirty snowball, passes near the sun it loses tons of material to vaporization. Thus, the number of orbits such a comet can make before being reduced to a swarm of gravel is limited. To give you an idea just how long these short period comets can exist, let me point out that the projected life span of one average sized short-period comet, that of Halley's comet, is only 40,000 years.

Now consider this. Comets are supposed to have been formed 4.6 billion years ago. During this looong period of time, any left over debris residing in the Kuiper Belt which could be nudged towards the Sun by gravitational perturbations from the outer planets (i.e., Jupiter, Saturn, Uranus, Neptune) or as a result of collisions between objects within this region should have been nudged by now. And, once these left over debris are nudged to become short period comets, they are expected to last only around 40,000 years.

In other words, by now, we should not be seeing any of these short period comets anymore, nada. And yet we still do.

Unless, the one doing the nudging of the left over debris residing in the Kuiper Belt is an object whose aphelion (or farthest distance from the Sun) takes it much farther away from the Kuiper Belt but whose perihelion (or nearest distance from the Sun) takes it closer than the Kuiper Belt.

Futhermore, the last perihelion of this object must have occurred no longer than 40,000 years ago.

So what is Planet X again? Planet X is simply a yet undiscovered regularly visiting object coming from regions much farther than the Kuiper Belt and believed by some to be the cause of some perturbations (if not total chaos) observed in regions much closer than the Kuiper Belt.

http://shugborough.info/blogs_read.php?blogid=4&blogpage=1&secid=-1

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http://shugborough.info/

dunno if i buy this site.

especially since no names of the 'scientists' are mentioned, anywhere.

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Short period comets are produced when Oort cloud or looooong period comets pass in front of one of the giant plaets in its orbit - the net effect is for it to lose a bunch of orbital energy and get nudged into a smaller orbit. Nothing mysterious about where they come from.

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Well it took two posts to counter this new theory. A new best I think. Honestly this theory is as bad as all the others we've heard before and can be shot down with little effort it seems.

Eulalio, could you provide us with the name of the scientist that came up with this idea, if there is such a scientist of course?

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A little less sensational than your other thread.

This is exactly my point! 10,000 years or 450,000 years lifetime of short period comets compared to the solar system's age of 4.6 billion years means the nudging of these leftover debris residing in the Kuiper Belt is fairly recent and must have been caused by an object whose aphelion takes it to regions much farther than the Kuiper Belt, but whose perihelion takes it nearer than the Kuiper Belt.

What I am saying is that none of the short period comets coming from the Kuiper Belt which we are seeing right now were nudged by the outer planets or by fellow objects residing in the Kuiper belt. Because if this is the case, they should have all disintegrated by now.

Edited by Eulalio

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Short period comets are produced when Oort cloud or looooong period comets pass in front of one of the giant plaets in its orbit - the net effect is for it to lose a bunch of orbital energy and get nudged into a smaller orbit. Nothing mysterious about where they come from.

Your statement is only partially true I am afraid. Not all short period comets originate from the Oort cloud, in fact only a few of them do. :rolleyes:

Majority of the short period comets originate from the Kuiper Belt where the leftover debris could have been nudged only by 3 possible causes:

1. They were nudged by gravitational perturbations from the outer planets (i.e., Jupiter, Saturn, Uranus, Neptune)

2. They were nudged as a result of collisions between objects within this region.

3. They were nudged by an object whose aphelion takes it much farther than the Kuiper Belt but whose perihelion takes it closer thant the Kuiper Belt. :sleepy:

Edited by Eulalio

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Well it took two posts to counter this new theory. A new best I think. Honestly this theory is as bad as all the others we've heard before and can be shot down with little effort it seems.

Eulalio, could you provide us with the name of the scientist that came up with this idea, if there is such a scientist of course?

I do believe I was able to counter all of your replies to my original post. :rolleyes:

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

That comets have finite lifespans has been known for some time. As they approach the Sun, its heat causes their volatile surfaces to sublimate into space, eating them gradually away. In order to still be visible over the age of the Solar System, they must be frequently replenished. One such area of replenishment is the Oort cloud; the spherical swarm of comets extending beyond 50 000 AU from the Sun first hypothesised by astronomer Jan Oort in 1950. It is believed to be the point of origin for long period comets, those, like Hale-Bopp, with orbits lasting thousands of years.

There is however another comet population, known as short period or periodic comets; those, like Halley, with orbits lasting less than 200 years. By the 1970s, the rate at which short-period comets were being discovered was becoming increasingly inconsistent with them having emerged solely from the Oort cloud. For an Oort cloud object to become a short-period comet, it would first have to be captured by the giant planets. In 1980, in the Monthly Notices of the Royal Astronomical Society, Julio Fernandez stated that for every short period comet to be sent into the inner solar system from the Oort cloud, 600 would have to be ejected into interstellar space. He speculated that a comet belt from between 35 and 50 AU would be required to account for the observed number of comets. Following up on Fernandez's work, in 1988 the Canadian team of Martin Duncan, Tom Quinn and Scott Tremaine ran a number of computer simulations to determine if all observed comets could have arrived from the Oort cloud. They found that the Oort cloud could not account for short-period comets, particularly as short-period comets are clustered near the plane of the Solar System, whereas Oort cloud comets tend to arrive from any point in the sky. With a belt as Fernandez described it added to the formulations, the simulations matched observations. Reportedly because the words "Kuiper" and "comet belt" appeared in the opening sentence of Fernandez's paper, Tremaine named this region the "Kuiper belt."

Edited by Eulalio

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A little less sensational than your other thread.

Although the median lifetime of short period comets is 450,000 years, there are some short period comets whose lifetime is estimated to be only 10,000 years.

This means that these comets must have been nudged from the Kuiper Belt no more than 10,000 years ago, which is really quite recent even in terms of human civilization.

This significantly lowers the maximum possible orbital period of Planet X.

There exists a very strong evidence that suggests that an object coming from regions much farther than the Kuiper Belt is indeed the one doing the sweeping and nudging of the leftover debris located at the Kuiper Belt. Furthermore, the amount of debris which it was observed to have swept away suggest that this object must be very massive.

I will be posting this evidence in my next post.

Edited by Eulalio

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I'm not sure that this can be considered proof of anything. It's a known fact that there are Plutinos in the kuiper belt, nobody is contesting that. Those are as liable to do the nudging and sweeping, as an alleged planet X. Same thing for all the objects, between 100 km in diameter and the plutinos, the eccentricity and inclination of current orbits makes them as liable, as the plutinos themselves, to do the nudging.

And yes, they found that the Oort cloud could not account for short-period comets, but that's how they stumbled upon the kuiper belt in the first place. Is that proof of planet X? In my opinion it is not.

Anyway, it's all theoretical anyway, the Pan-Starrs survey has not found a planet X in the Kuiper belt as of yet.

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Ignoring for a moment the dubious use of a blog as ``evidence'', or the uncanny similarity between one of the linked website's designers and your name, Eulalio...

  1. Of the 4 links at the bottom of the blog (none to actual peer-reviewed papers, of course), one is hopelessly out of date (from 2002). This is also the only one that the blog cites. Subsequent peer-reviewed research (Bernstein, 2004) gives reasonable explanations for the distribution of Kuiper-belt bodies, and - while not ruling out a large trans-Neptunian object - offers enough alternative explanations to rule out the existance the the so-called `Kuiper cliff' as proof of `Planet X'.
  2. The other three deal with the work of a single astronomer (P. Lykawka), and the `New Scientist' and `The Daily Galaxy' articles offer lots of counterpoints from other astronomers suggesting that the existence of `Planet X' is very tenuous, at best.

In short, the existence of a Mars- or Earth-sized planet out past ~50 AU cannot be conclusively ruled out, but is pretty unlikely. It would be a tremendously exciting discovery, which is why there are legitimate scientists still looking for it - but there is no `conclusive proof', either in scientific data or the historical record.

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Ignoring for a moment the dubious use of a blog as ``evidence'', or the uncanny similarity between one of the linked website's designers and your name, Eulalio...

  1. Of the 4 links at the bottom of the blog (none to actual peer-reviewed papers, of course), one is hopelessly out of date (from 2002). This is also the only one that the blog cites. Subsequent peer-reviewed research (Bernstein, 2004) gives reasonable explanations for the distribution of Kuiper-belt bodies, and - while not ruling out a large trans-Neptunian object - offers enough alternative explanations to rule out the existance the the so-called `Kuiper cliff' as proof of `Planet X'.
  2. The other three deal with the work of a single astronomer (P. Lykawka), and the `New Scientist' and `The Daily Galaxy' articles offer lots of counterpoints from other astronomers suggesting that the existence of `Planet X' is very tenuous, at best.

In short, the existence of a Mars- or Earth-sized planet out past ~50 AU cannot be conclusively ruled out, but is pretty unlikely. It would be a tremendously exciting discovery, which is why there are legitimate scientists still looking for it - but there is no `conclusive proof', either in scientific data or the historical record.

The "alternative explanations" which you say "rule out the existance of the so-called Kuiper cliff as proof of Planet X" refer to events which according to these scientists, occurred millions if not billions of years ago, and not fairly recently like less than 10,000 years ago only.

In my other post titled "Short period comets - proof of Planet X's recent passage", I discussed that whatever event or reason is used to explain the Kuiper cliff, or the nudging of the leftover debris in the Kuiper Belt, it must be an event which occurred less than 10,000 years ago, since we know for a fact that some short period comets have minimum lifetimes of only 10,000 years.

Edited by Eulalio

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The "alternative explanations" which you say "rule out the existance of the so-called Kuiper cliff as proof of Planet X" refer to events which according to these scientists, occurred millions if not billions of years ago, and not fairly recently like less than 10,000 years ago only.

In my other post titled "Short period comets - proof of Planet X's recent passage", I discussed that whatever event or reason is used to explain the Kuiper cliff, or the nudging of the leftover debris in the Kuiper Belt, it must be an event which occurred less than 10,000 years ago, since we know for a fact that some short period comets have minimum lifetimes of only 10,000 years.

I agree. The non-Planet X explanations for the Kuiper belt require that the belt be established billions of years ago in a singular or at least non-periodic event.

I do not agree that the existence of short period comets is proof of a periodic Planet X-like perturbation.

Consider, for example, the Trojan asteriods in Jupiter's orbit. These asteroids are in resonance with Jupiter's orbit, and have trajectories around the L4 and L5 Lagrange points. That is why they are still there, and have not either crashed into a planet or been ejected from the solar system.

However:

  1. Only an actual Lagrange point is stable. The vicinity of a Lagrange point is only quasi-stable. A single asteroid at the L4 Lagrange point may well stay there forever, but all the other asteroids near the L4 Lagrange point are therefore potentially in unstable orbits (although it may take thousands, millions, or billions of years for these orbits to decay).
  2. A Lagrange point only technically exists for an infinitesimally small mass between two larger masses. Obviously the asteroids themselves, while certainly possessing very small masses, are not infinitesimal. Also the Solar system is certainly not a 2-body problem. Therefore the `Lagrange points' in the Solar system are not true Lagrange points, only approximations thereof. Therefore even objects directly at the so-called `Lagrange points' are potentially in unstable orbits.
  3. It is impossible to analytically solve the 3-body problem, let alone a 1000-body problem. Therefore even in a Solar system consisting of only the Sun, Jupiter, and a single Trojan asteroid it is impossible to say whether or not that asteroid is in a stable orbit. Obviously our Solar system is more complicated than this.

Therefore I do not conclude that the presence of occasional short period comet is ``proof'' of an additional planet in our Solar system.

Indeed, it is far more likely, in my opinion, that the occasional small perturbations from neighbouring small-body asteroids and such is responsible for sporadically generating short period comets than a periodic massive perturbation from an elliptical planet. Such a planet would probably leave several large, and easily observed, holes in the Kuiper and asteroid belts (if it came that close).

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I agree. The non-Planet X explanations for the Kuiper belt require that the belt be established billions of years ago in a singular or at least non-periodic event.

I do not agree that the existence of short period comets is proof of a periodic Planet X-like perturbation.

The non-Planet X explanations for the Kuiper belt unfortunately is unable to explain another astronomical "anomaly" which further strengthens the existence of Planet X.

This anomaly is the existence of detached objects such as Sedna and 2000 CR105.

Other than the Kuiper belt, the only other region in our solar system which harbors clumps of small bodies beyond the orbit of Neptune is the Oort Cloud. The Oort cloud is located much farther away from the Kuiper Belt. The Oort cloud is believed to be 50,000 AU from the Sun while in comparison, the Kuiper Belt is believed to be only between 30-55 AU from the Sun.

Theoretically, there should be no objects found between the Kuiper Belt and the Oort cloud. But unfortunately, astronomers have found such objects which they call "detached objects".

http://en.wikipedia.org/wiki/Detached_object_(astronomy)

Detached objects are a dynamical class of bodies in the outer Solar System beyond the orbit of Neptune. These objects have orbits whose points of closest approach to the Sun (perihelion) are sufficiently distant from the gravitational influence of Neptune that they are essentially unaffected by Neptune and the other planets: this makes them appear to be “detached” from the Solar System.

In this way, they differ substantially from the majority of the known trans-Neptunian objects (TNOs), which form a loosely defined set of populations that have been perturbed to varying degrees onto their current orbit by gravitational encounters with the gas giant planets, predominantly Neptune.

Detached objects generally have highly elliptical, very large orbits with semi-major axes of up to a few hundred astronomical units (AU, the radius of Earth's orbit). Such orbits cannot have been created by gravitational scattering by the gas giants (in particular, Neptune). Instead, a number of explanations have been put forward, including:

1. an encounter with a passing star or

2. an encounter with a distant, planet-sized object located between the Oort cloud and the Kuiper Belt.

One detached object, namely, 2000 CR105, has an aphelion of 393.8 AU only. In comparison, the Oort cloud is believed to be located at roughly 50,000 AU from the Sun. This clearly eliminates the "encounter with a passing star" explanation as 2000 CR105 is located too deep in the solar system, and there are far too less number of detached objects obseved so far. An encounter with a passing star would have created far more number of detached objects located not too far from the Oort cloud itself, which is the nearest a passing star could get to our solar system without creating far more havoc.

An encounter with a distant, planet-sized object located between the Oort cloud and the Kuiper Belt would allow for small bodies located at the Kuiper Belt to be dragged farther away from the Kuiper Belt but at distances that do not come near the Oort cloud.

If you will notice, the non-Planet X explanations for the Kuiper belt is NOT included among those explanations that could explain the existence of detached objects.

Only the existence of Planet X can explain all at the same time the 3 observed anomalies in our solar system , namely:

1. The continued existence of short period comets

2. The Kuiper cliff

3. The existence of detached objects

Edited by Eulalio

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