Talk:Oort cloud

Wikipedia needs to lock in "hypothetical."
Some well intentioned editor keeps changing "hypothetical" to "theoretical." Perhaps they think it makes it sound more serious? I don't know exactly what their faulty thinking is.

There is a reason the first section is correctly titled the "Hypothesis" and NOT the "Theory."

When someone developes a model that explains phenomena, that "model" is a "theory."

Example: Einstein's theory of relativity.

When someone proposes "objects exist" to explain phenomena, those "objects" are "hypothetical" until their existence is empirically verified, at which point they are "fact."

Example: an 8th planet was hypothetical until Uranus was discovered, now it's fact.

A model will always remain a "theory." It does not matter how much evidence substantiates it, it will forever be a "theory."

Something theoretical forever remains theoretical (scientific theory).

Something hypothetical becomes fact with enough empirical evidence.

The Oort cloud is a hypothetical object (cloud of many objects) that is proposed as a source of long term comets. Currently, there is absolutely NO empirical evidence that it exists. However, if we one day do get enough empirical evidence of its existence, it goes from being "hypothetical" to being a "fact," something which cannot happen with a "theory." Hexakaidecanitarian (talk) 08:22, 20 May 2021 (UTC)

Before someone replies that "we DO have empirical evidence, long term comets" I'll deal with that now.

Long term comets, "fact," we "know" they exist. Long term comets are NOT part of the Oort cloud. Oort proposed long term comets in the past WERE part of the cloud, but somehow got knocked out.

An analogy: let's imagine we're at the bottom if a hill and we periodically see apples roll down the hill to us. We cannot see the top of the hill. I propose there is an apple tree at the top of the hill that has lots of apples, and something causes the apples to fall from the tree. Everyone with me agrees that is probably the case. I have NO empirical evidence of my hypothetical apple tree on the hill. Even though it makes good sense. Even though we know apples roll down the hill. And in this case we know all apples come from trees. The source "tree in this hill" has no empirical evidence.

Empirical evidence of the tree requires seeing the tree, touching the tree, hearing the trees branches in the wind, etc.

BTW, in this case, it happens to be that a monkey keeps stealing an old lady's apples and rolls them down the hill. No tree on the hill.

Likewise with the Oort cloud. We know there are long term comets. But there is no empirical evidence of a source "cloud." An, unlike the Apple tree, we don't even know if comments come from clouds of comets as their "source." Hexakaidecanitarian (talk) 09:26, 20 May 2021 (UTC)

Edit: by 8th planet I mean Neptune. Excuse my brain flatulence. Hexakaidecanitarian (talk) 11:52, 20 May 2021 (UTC)


 * It is "Theoretical" because astronomers have observed many comets coming directly from the Oort cloud (with inbound aphelia 10,000-70,000AU from the Sun). We know they came directly from the Oort cloud because we can calculate their barycentric orbits back into the past. (Heliocentric solutions at the same epoch will have even larger orbits because the solution will not include the gravity of Jupiter.) -- Kheider (talk) 14:58, 20 May 2021 (UTC)

@Kheider, "It is "Theoretical" because astronomers have observed many comets coming directly from the Oort cloud (with inbound aphelia 10,000-70,000AU from the Sun)." I mean no disrespect, but this sentence makes zero sense. Let's start with the second part,"astronomers have observed many comets coming directly from the Oort cloud (with inbound aphelia 10,000-70,000AU from the Sun). OK, they haven't observer the Oort cloud, so they haven't observed anything coming from it. Astronomers have observed long term comets with aphelia from 10,000-70,000AU. The existance of these long term comets is a fact.

The fact that these comets exist is why Oort proposed his hypothetical cloud. Oort proposed there is a cloud of planetesimals in that region, this hypothetical cloud is NOT the long term comets we have observed, such comets are proposed to have been kicked out of the Oort cloud at some distant past time. The Oort cloud has not been observed.

So, you're putting the cart before the horse. The factual, known existance of long term comets with aphelia 10,000-70,000AU from the barycenter is the reason Oort hypotisized a cloud of non-comets remaining out in that distant region that is the source of these known comets.

Now, lets look at the first part of this sentence, "It is "Theoretical" because"

This shows a basic lack of understanding of what differentiates a hypothesis from a scientific theory. A scientific theory is a "theory" from the moment it is conceived until the end of time. When a "theory" is put forth, it is a theory even when there is absolutely NO evidence to support it. And, later, when there is a mountain of evidence to support it, and everybody in the scientific community accepts it, it is then called a "theory" because a "theory" IS ALWAYS a "theory." A theory is a "model" that explains phenomena. It will forever be a "model" thus a "theory." A "hypothesis" is a testable, falsifiable idea. If someone once had a hypothesis that "elephants cannot swim" we simply test it. Observe elephants in water deeper than their height. We have observed this and the empirical evidence shows "elephants can swim = fact" thus falsifying the original hypothesis. Scientists collect empirical evidence (i.e. make observations) to either confirm a hypothesis (thus it becomes fact) or disprove it (falsify the hypothesis).

When the question at hand is simply whether or not an object exists, until it's existance is confirmed or disproven it is "hypothetical."

It doesn't matter if most of us consider it to be silly and unlikely (there is a giant space alien wandering way out there which occasionally poops out a mud ball towards the sun which freezes and becomes another long term comet) or serious and likely (there is a spherical cloud of planitessimals out there and occasionally something gets knocked out of the cloud and becomes a long term comet) both are called "hypothetical" until we observe just what is out there. Hexakaidecanitarian (talk) 10:05, 21 May 2021 (UTC)


 * It is theoretical as it is a successful working scientific model that explains all comets with periods greater than ~100000 years. Objects in the Oort cloud are on unstable orbits that are not perfectly spherical. Everything orbiting the Sun has a best-fit orbital period even if that period is millions of years. -- Kheider (talk) 13:12, 21 May 2021 (UTC)

Hypothetical
Just to make a point, I just thought up the Hexa giant impact hypothesis (a modified version of the giant impact hypothesis).

More than 4.5 billion years ago there existed an icy planet with a mass several times the mass of the earth with an orbital distance from the sun of about 20 AU. Let's call it planet Comet.

A massive interstellar object collided with this planet breaking it up into large pieces and propelling those pieces into the solar system. The Comet debris then had an orbit with a perihelion of about 1 AU and an apheliin of about 20 AU.

About 4.5 billion years ago the Comet debris field encountered a pre-Earth planet, let's call it Terra1. A large piece about the size of Mars struck Terra1 resulting in the formation of the Earth and the Moon (the Earth getting its abundance of water from this large icy Comet fragment).

Most of the debris field which missed Tera1 was then scattered in various directions at this collision yet the individual pieces still had an apheliin of about 20 AU.

But of the piece which struck Tera1, much of it exploded away losing momentum to the collision, a large mass of this collision debris had an aphelion of about 10 AU.

Over the next 4.5 billion years, the Earth and moon formed and cooled. And the now 2 debris fields continued to break up. Over time, further collisions resulted in short period comet orbits.

Due to collisions, tidal forces of near passes to planets, regular effects from the sun at perihelion, etc. the larger pieces continued to break up until now what remains are scattered smaller fragments.

This is my just formed hypothesis. Planet Comet, hypothetical. Planet Terra1, hypothetical. It doesn't matter him much I work on this, it doesn't matter if it all makes sense. These "objects" shall forever be called "hypothetical" unless we go back in time and OBSERVE them, and upon observing they become "fact." At no point can these objects be called "theoretical." IT'S SIMPLY THE *WRONG* WORD TO USE.

PS. I kinda like my new hypothesis. Hexakaidecanitarian (talk) 11:30, 21 May 2021 (UTC)


 * At this point Hexakaidecanitarian, your edits appear disruptive! -- Kheider (talk) 13:57, 21 May 2021 (UTC)

Final fix on hypothetical/theoretical, hopefully.
Since you cannot refer to an objects possible existance as theoretical (unless its proposed existance is solely the prediction of a model, such as the Higgs Boson). You cannot refer to "the Oort cloud" meaning the cloud itself as "theoretical" but instead must refer to the object as "hypothetical." However, when there is a theoretical concept surrounding the object, you can use "theoretical" to the concepts concerning the object. NASA worded it as so: https://solarsystem.nasa.gov/solar-system/oort-cloud/overview/

"Though long-period comets observed among the planets are thought to originate in the Oort Cloud, no object has been observed in the distant Oort Cloud itself, leaving it a theoretical concept for the time being. But it remains the most widely-accepted explanation for the origin of long-period comets."

Referring to the Oort cloud as a " theoretical concept" of a cloud is correct. Good job NASA.

To summarize: The entity "the Oort cloud" is "hypothetical." The concept "the Oort cloud" is "theoretical."

So let's finally agree on NASA's wording.

PS. Yes, this is pedantic. Hexakaidecanitarian (talk) 14:40, 21 May 2021 (UTC)


 * Comets that spend most of their time in the Oort cloud are members of the Oort cloud. (2002 RP120 is a TransNeptunian Object even though it comes well inside of Jupiter.) We have seen numerous comets that spend most of their time in the Oort cloud. The closer an object is to the Sun the faster it needs to move to maintain the orbit. Objects move slowest when furthest from the Sun (aphelion) and fastest when closest to the Sun (perihelion) and this is why Oort cloud comets spend most of their time in the Oort cloud. (Equal areas are swept out in equal times at any location in the ellipse.) While in the Oort cloud these slow moving objects are subject to numerous small perturbations that can make the object unbound/bound. The Oort cloud is theoretical regardless of whether it is called a concept, idea, or a substantiated scientific model. -- Kheider (talk) 19:21, 21 May 2021 (UTC)

This whole article
Most of the language in this article assumes the Oort cloud exists. Grassynoel (talk) 09:52, 13 January 2023 (UTC)

Relative distances
Relative distances of Oort Cloud and other trans Neptunes…. Statement others “are less than one thousandth as far from the Sun as the Oort Cloud” cannot be correct. Clarkecb (talk) 15:48, 26 January 2023 (UTC)
 * Neptune is 30au from the Sun while the outer Oort Cloud is around 50,000+au from the Sun. It might read better if we add "outer" as a qualifier. -- Kheider (talk)

The graphic in "Stellar perturbations and stellar companion hypotheses" has some wrong locations
The graphic in the "Stellar perturbations and stellar companion hypotheses" section has multiple factual errors, as mentioned in its talk page. Template:Solar_encounters has correct figures for at least the two mentioned in the talk page comment, though I haven't checked others.

I just removed it in hopes that someone can maybe either re-create the graphic or get the original author to fix the issues and re-add it. impinball (talk) 18:49, 19 February 2023 (UTC)

Corrected small misstake
I changed it from "Fastest probe" to "Once fastest probe" the parker solar probe currently is faster. 2A00:801:700:8A66:F66D:1459:EC6C:31A1 (talk) 16:52, 16 April 2024 (UTC)


 * @2A00:801:700:8A66:F66D:1459:EC6C:31A1 Dont mind if I did misstake, I am new to Wikipedia but I ain't stupid. 2A00:801:700:8A66:F66D:1459:EC6C:31A1 (talk) 16:55, 16 April 2024 (UTC)
 * @2A00:801:700:8A66:F66D:1459:EC6C:31A1 Yup fixed FalseWorldDictionary (talk) 17:26, 16 April 2024 (UTC)

Small fact correction
I have once again changed a small thing in the article. Voyager 1 is not the fastest probe, therfor it was changed to "once fastest". This is a usefull correction as it can be missleading to read it is the fastest. Signed FalseWorldDictionary. FalseWorldDictionary (talk) 15:13, 28 June 2024 (UTC)