The Oort Cloud Explained

[dcarrera]

IMO it's a nice story or "explanation" but no proof. Speculation, assumption, extrapolation is not good science.

Speculation, assumption and extrapolation are all part of science. You observe something that doesn't make sense, you speculate on possible solutions, you test them. Some times your guess is right, and some times it's wrong. When Copernicus speculated that the funky motion of Mars and the other planets in the sky would be explained better if the Sun was at the centre of the solar system, he did not have a way to test it, and his model didn't even work very well. Many years later came Kepler who replaced the circles that Copernicus was using with ellipses with variable speeds ("Kepler's Laws") and suddenly the model worked really way. And some years later Newton finally came up with the concept of "gravity" with a formula that explained why the planets would move the way Kepler said.... But it all began with speculation.

Seems that most of the stuff they are looking into these days has far too much space between the measurable, observable, repeatable things.

But it makes sense that "current research" should include a lot of things that are very difficult to observe. Things that are easy to observe and measure are usually things that we already understand so we've moved on to the next topic. You no longer see a lot of people arguing about whether Copernicus was right to put the Sun at the centre. When he came up with it, it was unobservable. NOW it is so easy to observe, nobody will argue about it.

It's like taking every 100th page of a book reading them out of order and predicting the story that was intended by the author.

If you had all the pages already and they were in order, the story would be already known.

 

[JacksBratt]

Speculation, assumption and extrapolation are all part of science. You observe something that doesn't make sense, you speculate on possible solutions, you test them. Some times your guess is right, and some times it's wrong.

Agreed, I work in research. When I speculate and or extrapolate data it is only due to time constraints and the true measurable data is always achieved before any conclusions are made or reports are given. Of course, my work needs to be bankable and peoples lives and reputations depend on solid fact. In the Oort cloud tale, no bank is going to argue, no lively hood is going to be bankrupt if you hand in your paper deeming it fact.

You see, I just have a problem with telling kids that it is fact. It should be stated that "some" people surmise that this is where they come from but we have NO REAL IDEA. Instead, we tell the student all this stuff is fact and then when they find out later that it is all just some egg heads personal idea, they think they can do the same. Truth loses it's integrity.

But it makes sense that "current research" should include a lot of things that are very difficult to observe. Things that are easy to observe and measure are usually things that we already understand so we've moved on to the next topic. You no longer see a lot of people arguing about whether Copernicus was right to put the Sun at the centre. When he came up with it, it was unobservable. NOW it is so easy to observe, nobody will argue about it.

That's just it. Until it is observed it should be just someones idea. It's not even a theory. A hypothesis at the very least.

If you had all the pages already and they were in order, the story would be already known.

Are you serious. I mean really, you needed me to put in the fact that you don't have any of the other pages, never did and had never read the book?

Let's try this again. Someone gives you 6 pages from a 600 page book. They are all out of order. They give the same six copies to 20 different people and you all have to, on your own, figure out the real story.

There, better?

 

[dcarrera]

You see, I just have a problem with telling kids that it is fact. It should be stated that "some" people surmise that this is where they come from but we have NO REAL IDEA.

I don't think that would be a fair characterization either. We really do have an idea. The Oort cloud is a hypothesis, and it should be presented as such. Acting like it is baseless speculation wrong. There are REASONS for the hypothesis. We do see long period comets, and the computer models that correctly produce the solar system also show a lot of icy bodies being ejected into wide orbits. This is a natural consequence of planet formation because the giant planets, especially Jupiter, are really good at ejecting things. For example, Jupiter is also the reason why there is so little mass in the asteroid belt, and why a planet could not form there.

Instead, we tell the student all this stuff is fact and then when they find out later that it is all just some egg heads personal idea, they think they can do the same. Truth loses it's integrity.

But it is not some egg head's personal idea. It is a serious proposal, with serious arguments behind it. It is not observed, and that makes it a hypothesis; but it is backed by physics, computer models, and it is the only sensible explanation for long period comets that anyone has come up with yet. This is the correct way to present the Oort cloud. Not as a fact, but also not as wild speculation.

Let's try this again. Someone gives you 6 pages from a 600 page book. They are all out of order. They give the same six copies to 20 different people and you all have to, on your own, figure out the real story.

I don't want to stretch the analogy. The point I was making is that you should expect that any current research must include things that are not well understood, and things that we would like to observe but can't observe yet. Anything that is already well understood and is already very well observed is, by definition, not research. Everything that we understand now was once not well understood. Many of the things we are trying to figure out right now will one day become well understood.

 

[Michael]

I don't think that would be a fair characterization either. We really do have an idea. The Oort cloud is a hypothesis, and it should be presented as such. Acting like it is baseless speculation wrong. There are REASONS for the hypothesis. We do see long period comets, and the computer models that correctly produce the solar system also show a lot of icy bodies being ejected into wide orbits. This is a natural consequence of planet formation because the giant planets, especially Jupiter, are really good at ejecting things. For example, Jupiter is also the reason why there is so little mass in the asteroid belt, and why a planet could not form there.




But it is not some egg head's personal idea. It is a serious proposal, with serious arguments behind it. It is not observed, and that makes it a hypothesis; but it is backed by physics, computer models, and it is the only sensible explanation for long period comets that anyone has come up with yet. This is the correct way to present the Oort cloud. Not as a fact, but also not as wild speculation.



I don't want to stretch the analogy. The point I was making is that you should expect that any current research must include things that are not well understood, and things that we would like to observe but can't observe yet. Anything that is already well understood and is already very well observed is, by definition, not research. Everything that we understand now was once not well understood. Many of the things we are trying to figure out right now will one day become well understood.

How very odd, and somewhat disconcerting that I actually find myself in agreement with you on some point related to astronomy.

 

[dad]

The Sun. Absolutely the Sun. The Sun completely dominates the gravitational potential of the solar system. Every giant planet has rings. Saturn only has the biggest and most beautiful ones.

"The outer Oort cloud is only loosely bound to the Solar System, and thus is easily affected by the gravitational pull both of passing stars and of the Milky Way itself. "

https://en.wikipedia.org/wiki/Oort_cloud

To be fair to the fable, the imaginary cloud can be pulled and tugges every which way!!

Now you need to prove the foundational claim the cloud sits in...or it is nonsense...

Astronomers conjecture that the matter composing the Oort cloud formed closer to the Sun and was scattered far into space by the gravitational effects of the giant planets early in the Solar System's evolution

 

[dcarrera]

"The outer Oort cloud is only loosely bound to the Solar System, and thus is easily affected by the gravitational pull both of passing stars and of the Milky Way itself. "

https://en.wikipedia.org/wiki/Oort_cloud

The question was whether the Oort cloud objects would be bound to the Sun or a planet. The question was not whether the object is STRONGLY bound to the Sun. Everything I said is 100% correct. The Sun's gravitational potential is a thousand times stronger than that of the most massive planet.

 

[dad]

The question was whether the Oort cloud objects would be bound to the Sun or a planet. The question was not whether the object is STRONGLY bound to the Sun. Everything I said is 100% correct. The Sun's gravitational potential is a thousand times stronger than that of the most massive planet.

Well, a spaceship can be bound to a planet or sun. Yet when another force is applied to it, it changes that! Therefore if there are other forces affecting comets, some of which science admits and is aware of...one can assume that the immediate orbit path of a comet we see here, could have been affected somehow. To lock into that path and make big pronouncements about the past based on that is asinine.

 

[dcarrera]

Well, a spaceship can be bound to a planet or sun.

Do I REALLY need to explain to you Newton's law of gravitation? Do I REALLY need to tell you that comets are not in orbit around planets? SERIOUSLY?

Therefore if there are other forces affecting comets, some of which science admits and is aware of...

Which force do you have in mind?

 

[dad]

Do I REALLY need to explain to you Newton's law of gravitation? Do I REALLY need to tell you that comets are not in orbit around planets? SERIOUSLY?

Doesn't matter. Planets could affect it. If a comet passed too close to the biggest planet in the solar system, could it not affect the path? I notice this from science..

"Gas giant planets that migrated early in the history of the solar system could have violently knocked some of the asteroid belt's denizens into their current orbits, .."

http://www.space.com/6981-migrating-planets-kicked-asteroids-orbit.html Since a previous link I gave mentioned stars also can affect the comet, we can add that.

Which force do you have in mind?

Better to have another cup of 'we don't know'.

We could speculate, and guess. I could imagine that when the earth zone changed in nature sometime after the flood (any change for earth would obviously be wider than just earth) that some bodies changed in some ways. Planets could have been drawn closer to earth than they once were...debris from this sort of thing and/or the violent expulsion of some material from this planer in the flood year could have changed paths and orbits...etc etc. Even if a lot of debris and ice and etc escaped from earth in the flood year, and assumed some orbital path...that could likely have been changed later when the nature change happened also! One can always speculate. That is what science does, except they use godless speculation ad nauseam.

 

[dcarrera]

Doesn't matter. Planets could affect it. If a comet passed too close to the biggest planet in the solar system, could it not affect the path?

For the zillionth time, the question was whether comets orbit planets or the Sun. The question was not whether, at some point in the past, comets could have come close to a planet. If you bothered to look at the post where I describe the origin of the Oort cloud, you'll see me talking about giant planet, and scatters, and the asteroid belt. But if someone asks me whether comets are orbiting a planet, the answer is "no".

I could imagine that when the earth zone changed in nature sometime after the flood...

Sigh...

 

[dad]

For the zillionth time, the question was whether comets orbit planets or the Sun. The question was not whether, at some point in the past, comets could have come close to a planet.

Not really. The actual issue is whether the current orbits which 'woulda coulda shoulda' mean that it might take say a million years for one orbit represent some actual unaffected path or not. The answer is you sure as hec do not know. Period.

If you bothered to look at the post where I describe the origin of the Oort cloud, you'll see me talking about giant planet, and scatters, and the asteroid belt.

Imaginary giant planet to be precise. Imaginary scatter too. The whole model is bogus and fiction. Godless drivel. If anyone takes that the least bit seriously they need help.

But if someone asks me whether comets are orbiting a planet, the answer is "no".

I think we get that much. One of the main issues here is the claimed loooooooong orbits and origins, and 'the cloud'.

I know it is particularly difficult for those who spend a long time memorizing this nonsense and thought they knew what they were talking about.

 

[Astrophile]

Doesn't matter. Planets could affect it. If a comet passed too close to the biggest planet in the solar system, could it not affect the path?

The simple answer is 'yes'. In recent times short-period comets have had their orbits changed dramatically by close enounters with Jupiter; examples are Comets Whipple, Brooks, Lexell, Shoemaker-Levy 9, and Churyumov-Gerasimenko. However, astronomers are well aware of these planetary perturbations and are able to calculate their effects on the orbits of the comets. Moreover, most Oort cloud comets do not move in the plane of the ecliptic and so are relatively safe from close encounters with the giant planets.

Even in the 18th century astronomers were able to allow for planetary pertubations when they were predicting the reappearance of Halley's Comet in 1758-9. Since then astronomers have been able to calculate Halley's orbit accurately enough to identify all its past appearances back to 240 BC. I mention this to show that perturbations of cometary orbits are not unknown quantities that make it impossible to predict the movements of comets.

To return to Oort cloud comets, most of them will not experience close encounters with any of the giant planets during a single perihelion passage, and the perturbations that they do experience are routinely allowed for in calculations of their paths. There is therefore no doubt that the comets genuinely have orbital radii of thousands or tens of thousands of AU, and periods of up to a few million years.

 

[dad]

The simple answer is 'yes'. In recent times short-period comets have had their orbits changed dramatically by close enounters with Jupiter; examples are Comets Whipple, Brooks, Lexell, Shoemaker-Levy 9, and Churyumov-Gerasimenko.

Bingo.

However, astronomers are well aware of these planetary perturbations and are able to calculate their effects on the orbits of the comets.

They are not aware of past state change perturbations!

Moreover, most Oort cloud comets do not move in the plane of the ecliptic and so are relatively safe from close encounters with the giant planets.

Since that cloud is imaginary, that says nothing. Even if many comets came from that direction, that does not mean that the planets were where they now are before the nature change! Nor does it mean other things were not acting in a way that changed orbital paths.

Even in the 18th century astronomers were able to allow for planetary pertubations when they were predicting the reappearance of Halley's Comet in 1758-9. Since then astronomers have been able to calculate Halley's orbit accurately enough to identify all its past appearances back to 240 BC. I mention this to show that perturbations of cometary orbits are not unknown quantities that make it impossible to predict the movements of comets.

That only applies in recent years, and in this state. You do nothing here but assume that is all there ever was ...for no reason...and model according to that belief. Busted ye be.

To return to Oort cloud comets, most of them will not experience close encounters with any of the giant planets during a single perihelion passage,

God put planets where they are. In any nature change that place may have drastically changed. They are here for us! They are here for us in this state!

There is therefore great doubt that the comets genuinely have orbital radii of thousands or tens of thousands of AU, and periods of up to a few million years. In fact that is absurd, belief based in entirety, and not the truth.

 

[dcarrera]

God put planets where they are. In any nature change that place may have drastically changed. They are here for us! They are here for us in this state!

Wow... just wow...

 

[Astrophile]

Bingo.
They are not aware of past state change perturbations!

Since that cloud is imaginary, that says nothing. Even if many comets came from that direction, that does not mean that the planets were where they now are before the nature change! Nor does it mean other things were not acting in a way that changed orbital paths.
That only applies in recent years, and in this state. You do nothing here but assume that is all there ever was ...for no reason...and model according to that belief. Busted ye be.
God put planets where they are. In any nature change that place may have drastically changed. They are here for us! They are here for us in this state!

There is therefore great doubt that the comets genuinely have orbital radii of thousands or tens of thousands of AU, and periods of up to a few million years. In fact that is absurd, belief based in entirety, and not the truth.

There is obviously no common ground between us, so there is no point in continuing this discussion.

 

[dad]

Wow... just wow...

Right, the planets have an effect on protecting us don't they? In this present state, there are lots of asteroids and debris out there....

"

Is it true that Jupiter could be considered our friendliest planet because – without Jupiter – comets would be more likely to hit us?

The answer is yes … and no. Some astronomers believe that one reason Earth is habitable is that the gravity of Jupiter does help protect us from some comets."

http://earthsky.org/space/is-it-true-that-jupiter-protects-earth

 

[dad]

There is obviously no common ground between us, so there is no point in continuing this discussion.

As long as you cling to a belief that the current nature on and near earth must be how it always was, you are lost in space. That is the point, your fantasy is no longer accepted and cannot be called true or fact or proven or evidenced.

Cheers.

 

[lesliedellow]

It may be good for a laugh.

If I want to find myself rolling on the floor in hysterics, all I have to do is read one of your posts.

 

[dad]

If I want to find myself rolling on the floor in hysterics, all I have to do is read one of your posts.

Laugh all you like. The question is what others can laugh at, what God laughs at, and what is actually funny.

 

[dcarrera]

Right, the planets have an effect on protecting us don't they? In this present state, there are lots of asteroids and debris out there....

"

Is it true that Jupiter could be considered our friendliest planet because – without Jupiter – comets would be more likely to hit us?

The answer is yes … and no. Some astronomers believe that one reason Earth is habitable is that the gravity of Jupiter does help protect us from some comets."

http://earthsky.org/space/is-it-true-that-jupiter-protects-earth

It says "some". I am an astronomer and I work on orbital dynamics. I do not think that Jupiter helps. I think it is more trouble than it's worth, and I can't think of any dynamicist (or otherwise) who thinks that Jupiter keeps the Earth safe. But the "wow" part was at the bewildering arrogance of yours in believing that planets were put there for you.