Oort cloud and comets

Nov 2, 2020
177
129
260
Good evening everyone, today I spent a reasonable part of the day watching videos about the solar sistem. I noticed how important is the so-called "oort cloud" for the study of comets and their history. If I'm not mistaken the oort-cloud can be seen as a verge, the verge of our solar sistem since there is nothing out there that can be considered part of our sistem. The composition of the oort clod is dusty, there is the presence of dust and rocks. And what's more, the shape is that of a sphere. The question is the following: what is the nexus (if there is one) between the oort cloud and the comets? I know there is something, but I didn't understand what...
 
  • Like
Reactions: rod

rod

Oct 22, 2019
1,992
717
2,560
"The question is the following: what is the nexus (if there is one) between the oort cloud and the comets?"

This report and 22 page arXiv paper is the most detailed I have read on the Oort cloud and comets in our solar system. 'Astronomers calculate genesis of Oort cloud in chronological order', https://phys.org/news/2021-06-astronomers-genesis-oort-cloud-chronological.html

My observation. Simulations require assumptions about initial conditions or starting conditions to calculate. This statement is a good example of assumption in the model. "The Oort cloud, the Leiden simulations confirm, is a remnant of the protoplenatary disk of gas and debris from which the Solar system emerged some 4.6 billion years ago. The comet-like objects in the Oort cloud come from roughly two places in the Universe. The first part of the objects comes from close by, from the Solar system. These debris and asteroids have been thrown out by the giant planets. However, some of the debris did not succeed in doing so and is still in the asteroid belt between Mars and Jupiter. A second population of objects, the Leiden astronomers conluded, comes from other stars. When the Sun was just born, there were about a thousand other stars in the vicinity. The Oort cloud may have captured comets that originally belonged to those other stars." If this assumption is not correct for the origin of the Sun, the simulation is not valid or may have other issues.

Reference, “Oort cloud Ecology II: The chronology of the formation of the Oort cloud, https://arxiv.org/abs/2105.12816, 26-May-2021. "We present a chronology on the formation and early evolution of the Oort cloud and test the sequence of events of its formation by simulating the formation process in subsequent amalgamated steps."

On page 3 of the report the Oort cloud mass estimates are provided. “The mass of the Oort cloud is estimated to range from 1.9Mearth (Weissman 1996) to 38Mearth (Weissman 1983). These estimates seem somewhat on the high side when compared to those based on numerical simulations, which arrive at 0.75 +/-0.25Mearth (Brasser 2008) to 1.0 +/- 0.4Mearth (Fernández & Brunini 2000). With a typical comet-mass of a few times 10^12 to 10^14 kg (Rickman et al. 1987; Sosa & Fernández 2009, 2011) the Oort cloud contains 10^12 comet-sized objects. Interestingly, this estimate is comparable to Oort’s original estimate of ~ 10^11 objects (Oort 1950), and to the density of interstellar asteroids (Engelhardt et al. 2017; Portegies Zwart et al. 2018; ’Oumuamua ISSI Team et al. 2019; Pfalzner et al. 2020).”

My observation. Without the Oort cloud, short period and long period comets including comets that make only one perihelion pass by the Sun today, do not fit the 4.6 billion years old solar system model based upon meteorite radiometric dating methods. Comets in the solar system today suggest a much more recent origin and much younger age in the solar system if there is no migration from the Oort cloud for many comets observed today. Direct observations of the Oort cloud remain elusive unlike direct observations of stellar parallax for stars or observations and measurements for asteroids in the solar system today like 4 Vesta or the Galilean moons at Jupiter.
 
Last edited:
Nov 2, 2020
177
129
260
Wow, there is a lot of material here. Thank you very much Rod, even if I'm a beginner I understood the topic in its generality. Today I'll read the pages to enrich, if I'll manage to do it, my knowledges. Thank you again.
One last thing: is the composition of the oort cloud an that of the kuper belt roughly the same, right?
 

rod

Oct 22, 2019
1,992
717
2,560
Wow, there is a lot of material here. Thank you very much Rod, even if I'm a beginner I understood the topic in its generality. Today I'll read the pages to enrich, if I'll manage to do it, my knowledges. Thank you again.
One last thing: is the composition of the oort cloud an that of the kuper belt roughly the same, right?
My answer to your question - I do not know :) Consider the Oort cloud today is said to have some 1 to 38 earth masses and 10^12 comets (none directly observed or spectrums obtained for them). Consider the size of the Kuiper Belt today. MS BING search reports, "Kuiper Belt Despite its vast extent, the collective mass of the Kuiper belt is relatively low. The total mass is estimated to range between 1/25 and 1/10 the mass of the Earth. Conversely, models of the Solar System’s formation predict a collective mass for the Kuiper belt of 30 Earth masses."

The 30 earth mass Kuiper belt is not observable in the solar system today and the Oort cloud, no direct observations or direct comet spectra are obtained today either. Both are origin model dependent interpretations.
 
  • Like
Reactions: vincenzosassone
Jun 1, 2020
1,277
1,050
3,060
"The question is the following: what is the nexus (if there is one) between the oort cloud and the comets?"

This report and 22 page arXiv paper is the most detailed I have read on the Oort cloud and comets in our solar system. 'Astronomers calculate genesis of Oort cloud in chronological order', https://phys.org/news/2021-06-astronomers-genesis-oort-cloud-chronological.html

My observation. Simulations require assumptions about initial conditions or starting conditions to calculate. This statement is a good example of assumption in the model. "The Oort cloud, the Leiden simulations confirm, is a remnant of the protoplenatary disk of gas and debris from which the Solar system emerged some 4.6 billion years ago. The comet-like objects in the Oort cloud come from roughly two places in the Universe. The first part of the objects comes from close by, from the Solar system. These debris and asteroids have been thrown out by the giant planets. However, some of the debris did not succeed in doing so and is still in the asteroid belt between Mars and Jupiter. A second population of objects, the Leiden astronomers conluded, comes from other stars. When the Sun was just born, there were about a thousand other stars in the vicinity. The Oort cloud may have captured comets that originally belonged to those other stars." If this assumption is not correct for the origin of the Sun, the simulation is not valid or may have other issues.
Nice assessment.


My observation. Without the Oort Cloud, short period and long period comets including comets that make only one perihelion pass by the Sun today, do not fit the 4.6 billion years old solar system model based upon meteorite radiometric dating methods.
I don’t follow your view. Meteorites are dated to over 4.5 Gyrs. [Here]
Free fall time from the outer Oort is ~ 22 Myrs. But they require something to trigger a fall.

Also, the estimated mass of the Earth based crudely on the assumption that Halley’s comet is typical is about 5 Earth mass. For objects to be flung that far, they must be small, thus none have been found. Even Jupiter would be beyond optical viewing (i.e. HST) if it were placed in the inner region of the Oort.
 
Last edited:
Nov 2, 2020
177
129
260
I want to thank you again Rod for the time you devoted to me. Now I ended my studies about Oort cloud (even if I'll continue to repeat them as well as everything about astronomy and astrophysics). I have written the main points about the two topics, I share them to exemplify the work of others:
Oort Cloud:
  • What is: a protoplanetary disk of objects thrown out during the formation of the system.
  • Where they are from: there is the possibility they come from both our solar system and other systems close by.
  • Composition: unknown, maybe they are rocky and dusty like the asteroid belt’s objects (perhaps the main belt and the Oort Cloud share the same composition since they were originated by the same debris).
  • Fundamental blocks: comet-like objects.
  • It can’t be seen by us. (too far, too dark)
  • There isn’t a nexus between Oort Cloud and Kuiper belt.
  • Oort Cloud is thought to be 30 times the mass of our planet, whereas we can observe a Kuiper belt made by materials that make it weighs between 1/25 to 1/10 Earth masses. Both the systems in question are too far to be properly observed, especially the Oort Cloud.
  • Maybe this hypothesis was given to explain the discrepancy between the theorized mass of the Kuiper belt and the mass it actually has. (this is something I think)
  • Spherical object as a shell at the edges of our system.
  • It’s made of comets that lost their orbit with the Sun.
  • It was born after the birth of the Sun. I must say that it can also be considered to be relatively young in comparison of the solar system. The escape from the Sun’s orbit happened after 20 to 50 million years after the formation of the Sun itself.
  • We know the radius: 1 light year.
  • About a quarter of the material of the Oort Cloud could be non-native of our system but captured by other systems. And what’s more, our Sun during its youth could have been part of a cluster of stars, just for this reason is possible to assume that the material in question is from those stars.
Comets:
  • They can be divided into two groups: short period and long period comets.
  • Oort Cloud helps explain why comets come from different angles of the solar system.
  • Comets' lifespan is relatively short for our solar system.
  • When comets orbit the Sun they increase more and more their eccentricity. Doing so, they begin to get further and further until they reach the point of no-return and go away. They reach the Oort Cloud.
I'm not totally sure about the last part of Comets, and as I always say, correct me if I'm wrong (I'm probably wrong in the last point). I know for who already knows the topic isn't pleasing to read it, for this reason I suggest people who want to read to only analise the part of the Comets even with a fast look.
 
Last edited:
  • Like
Reactions: Helio and rod
Nov 2, 2020
177
129
260
Free fall time from the outer Oort is ~ 22 Myrs. But they require something to trigger a fall.
As far as I know by reading the material given by Rod, the giant planets can be elements causing it.
I don’t follow your view. Meteorites are dated to over 4.5 Gyrs. [Here]
I don't know exactly, but meteorites can be dated over 4.5 Gyrs since they are the remnants of the protoplanetary system. They were in existence before the Sun itself, and what's more, after all the protoplanetary system changed turning into the most important elements of solar system that today we know, asteroids and meteores remained the same elements.
Also, the estimated mass of the Earth based crudely on the assumption that Halley’s comet is typical is about 5 Earth mass. For objects to be flung that far, they must be small, thus none have been found. Even Jupiter would be beyond optical viewing (i.e. HST) if it were placed in the inner region of the Oort.
This is a good point to analyze!
 

rod

Oct 22, 2019
1,992
717
2,560
Post #7 said "Comets: They can be divided into two groups: short period and long period comets.
Without the Oort Cloud they couldn’t exist..."

Comet lifetimes compared to the radiometric ages of meteorites used (cluster around 4.56 billion years old), comet lifetimes in the solar system are very short compared to billions of years. My point about no Oort cloud, the comets in the solar system we see are not that old because of their short orbital lifetimes in the heliocentric solar system so a replenish mechanism is needed to explain their presence in the solar system today. Otherwise age calculation problems could arise.

The Oort cloud helps explain comets observed entering the solar system from different angles relative to the Sun and ecliptic today but the Oort cloud is not imaged too like we see other bodies in the solar system, e.g. the Galilean moons at Jupiter or Saturn's rings and moons.
 
Last edited:
  • Like
Reactions: vincenzosassone
Jun 1, 2020
1,277
1,050
3,060
Why do we expect a huge gap between the Kuiper Belt and the Oort?

I’m fairly sure the Oort objects are in orbit and in the farthest reach of the Sun’s gravitational grip.

Their age should be primordial as planetismals from early once the disk forms, or am I missing something?
 
  • Like
Reactions: vincenzosassone
Jun 1, 2020
1,277
1,050
3,060
Comet lifetimes compared to the radiometric ages of meteorites used (cluster around 4.56 billion years old), comet lifetimes in the solar system are very short compared to billions of years.
We could, I suppose, consider all the likely trillion + Oort objects as comets, thus their age is very likely primordial.

My point about no Oort cloud, the comets in the solar system we see are not that old because of their short orbital lifetimes in the heliocentric solar system so a replenish mechanism is needed to explain their presence in the solar system today. Otherwise age calculation problems could arise.
If they are in stable, somewhat circular orbits, seeing few long term comets is expected. A passing star would be needed to trigger some to come “south”.



The Oort cloud helps explain comets observed entering the solar system from different angles relative to the Sun and ecliptic today but the Oort cloud is not imaged too like we see other bodies in the solar system, e.g. the Galilean moons at Jupiter or Saturn's rings and moons.
Yes, and it’s ironic to me that we can see directly perhaps a dozen exoplanets much, much farther away but no Oort objects. The reason this is so I will reserve for a quiz question. ;)
 
  • Like
Reactions: vincenzosassone
Nov 2, 2020
177
129
260
Post #7 said "Comets: They can be divided into two groups: short period and long period comets.
Without the Oort Cloud they couldn’t exist..."

Comet lifetimes compared to the radiometric ages of meteorites used (cluster around 4.56 billion years old), comet lifetimes in the solar system are very short compared to billions of years. My point about no Oort cloud, the comets in the solar system we see are not that old because of their short orbital lifetimes in the heliocentric solar system so a replenish mechanism is needed to explain their presence in the solar system today. Otherwise age calculation problems could arise.

The Oort cloud helps explain comets observed entering the solar system from different angles relative to the Sun and ecliptic today but the Oort cloud is not imaged too like we see other bodies in the solar system, e.g. the Galilean moons at Jupiter or Saturn's rings and moons.
Thank you again, I'm sorry for bothering you but now I finished since I have solved the problem of comets. I also modified that part in order to give to our mates something of worth.
 
Nov 2, 2020
177
129
260
Why do we expect a huge gap between the Kuiper Belt and the Oort?
I'm not totally sure about it, but if Oort Cloud had been hypotized to be closer we would have had problem since we could have been able to see it even if it wasn't present in that region of the space.
I mean, if it was closer we could see it, but it isn't.
Yes, and it’s ironic to me that we can see directly perhaps a dozen exoplanets much, much farther away but no Oort objects. The reason this is so I will reserve for a quiz question.
This would be beautiful!
 

rod

Oct 22, 2019
1,992
717
2,560
Interesting. From what I can gather in all of this discussion, we do not see the Oort Cloud today and the Kuiper Belt observed today is much smaller in mass and number of objects than initial conditions assumed for the primordial solar nebula and accretion disk said to exist some 4.5 billion years ago. So we do not see the Oort cloud and we do not see the original Kuiper belt. I am glad Galileo did not use *observational* arguments like this against the geocentric teachers :)
 
  • Like
Reactions: vincenzosassone
Jun 1, 2020
1,277
1,050
3,060
...So we do not see the Oort cloud and we do not see the original Kuiper belt. I am glad Galileo did not use *observational* arguments like this against the geocentric teachers :)
Galileo erroneously used tidal arguments and his persuasive style to bully the reader into adopting his view. This nearly ruined him.

The early KBO hypothesis is now mainstream with solid observations, though a refined total mass value is undetermined.

I’m not sure what size scope, perhaps in the IR, will be needed to detect Oort objects. Or maybe transits will prove helpful. The fact that we can falsify the claims means we have a valid theory.

I suspect that with improved planetary formation models — demonstrating likely wild migration schemes that would produce copious amounts of tossing planetismals — we will see better estimates of what may be found at the outer regions of the solar system.
 
  • Like
Reactions: vincenzosassone

rod

Oct 22, 2019
1,992
717
2,560
FYI. Galileo used the telescope and could see the tiny lights moving around Jupiter. Others in his time could do the same if they looked through the telescope. The early KBO is not observable today in telescopes so Galileo's methods documenting the Galilean moons were solid observations that others can still see today using telescopes and make accurate predictions concerning their motions and eclipse events visible. Telescopes today do not see or image the Oort cloud either. No one sees the early KBO like we can see the Galilean moons orbiting Jupiter using telescopes. Issues like this should be transparent to the public.
 
Jun 1, 2020
1,277
1,050
3,060
FYI. Galileo used the telescope and could see the tiny lights moving around Jupiter. Others in his time could do the same if they looked through the telescope.
I’ve not seen anything that would support this view, though the four moons are bright. Hans likely had inferior lenses. Galileo used, perhaps, superior glass from Florentine and he was both a precisionist and a craftsman.

His astronomy knowledge made him quickly suspect they weren’t stars as they aligned with ecliptic.

early KBO is not observable today in telescopes so Galileo's methods documenting the Galilean moons were solid observations that others can still see today using telescopes and make accurate predictions concerning their motions and eclipse events visible. Telescopes today do not see or image the Oort cloud either. No one sees the early KBO like we can see the Galilean moons orbiting Jupiter using telescopes. Issues like this should be transparent to the public.
Agreed, objective evidence should always be the objective! :)
 
  • Like
Reactions: vincenzosassone
Nov 2, 2020
177
129
260
I am glad Galileo did not use *observational* arguments like this against the geocentric teachers
I'm glad we're talking about Galileo from a sentence like this in a forum that share nothing with the topic :tearsofjoy:. Anyway, I really like this happened, you know, Galileo was (and still is) one of the most important scientists of my country! His behaviour was much bully, this is true, but I can assure this, now he is remembered as one of strenuous opponents to the obscurantism made by the church. For this reason he is a sort of national hero (maybe this word is too much though).
The worst thing he had to bear was that no one wanted to see through his telescope (according to the church it was a demoniac object) and his empirical proof weren't accepted...
 
  • Like
Reactions: Catastrophe

Catastrophe

Approaching asteroid? Is this THE one?
Feb 18, 2020
2,794
1,718
6,070
Unless I am out of date (very possible) the Oort Cloud cannot be seen.
"The Oort Cloud has never actually been observed - its existence was suggested by the Dutch astronomer J H Oort to explain the trajectories and number of long-period comets . . . . . . . . . "
Collins Discovery Guides Universe from the big bang to black holes Ed Pam Spence 2016.

Cat :)
 
  • Like
Reactions: rod and Helio

rod

Oct 22, 2019
1,992
717
2,560
This exoplanet site shows 14 star systems with multiple exoplanets, 6 to 8 is the number I selected in my query. The Extrasolar Planet Encyclopaedia — Catalog Listing (exoplanet.eu)

The 14 solar systems listed with 6 to 8 exoplanets each, range in age from 2 to 8.5 billion years old. Are Oort clouds confirmed at these other solar systems? Example, TRAPPIST-1 with 7 planets, KOI-351 with 8 planets, Kepler-80 with 6 planets considered 2 billion years old.

My answer is no. Consider how difficult it is to directly image the Oort cloud here (like Galileo's views of the Galilean moons moving around Jupiter, very objective evidence against geocentric astronomy), let alone somewhere else like 21 to 3,000 light-years away :)
 
Last edited:
  • Like
Reactions: vincenzosassone

Catastrophe

Approaching asteroid? Is this THE one?
Feb 18, 2020
2,794
1,718
6,070
Rod, there are all sorts of figures floating around, concerning distance of Oort Cloud, which is not surprising as you can't see it and it is really anybody's guess. Wiki gives:

"The presumed distance of the Oort cloud compared to the rest of the Solar System
The Oort cloud is thought to occupy a vast space from somewhere between 2,000 and 5,000 au (0.03 and 0.08 ly)[9] to as far as 50,000 au (0.79 ly)[5] from the Sun. Some estimates place the outer boundary at between 100,000 and 200,000 au (1.58 and 3.16 ly)."

I think the Kuiper Belt is reckoned to start at 30 AU (Neptune) and go to 50-100 AU.

Cat :)
 
  • Like
Reactions: rod

Catastrophe

Approaching asteroid? Is this THE one?
Feb 18, 2020
2,794
1,718
6,070
So Cat et al. We have a flexible size (and mass) for the Oort cloud we do not see and other solar systems documented now that we do not see Oort clouds there either. It is always good to be flexible when explaining How The Universe Works :)
Yes, when you think about it, comets at that distance and obviously without tails, are going to be nigh impossible to see.

Cat :)

I checked the average distance between stars:
Quote
What is the Average Distance Between Stars in our Galaxy ...
https://public.nrao.edu › ask › what-is-the-average-dista...

27 Feb 2021 — Answer: I think what you are asking for is the average distance between any two stars in our galaxy. That number turns out to be about 5 light ...
Quote

So alpha and Proxima are not far from average distance. Of course it does not mean that every star has another star about 5ly away in every direction (allowing for spacing) but it could mean, following what Wolfshadw posted, that there is a network of Oort Clouds permeating large tracts (or all) of the galaxy. If there is anything in the idea of life being spread by comets . . . . . . . . . . . . . . . that has some mighty implications.

Cat :)

Remember you saw it here.
 
Last edited:
Jun 1, 2020
1,277
1,050
3,060
I'm glad we're talking about Galileo from a sentence like this in a forum that share nothing with the topic :tearsofjoy:. Anyway, I really like this happened, you know, Galileo was (and still is) one of the most important scientists of my country! His behaviour was much bully, this is true, but I can assure this, now he is remembered as one of strenuous opponents to the obscurantism made by the church. For this reason he is a sort of national hero (maybe this word is too much though).
The worst thing he had to bear was that no one wanted to see through his telescope (according to the church it was a demoniac object) and his empirical proof weren't accepted...
Yes, Galileo is arguably the father of modern science. His letter to the Grand Duchess Christina is a remarkable account of the importance of objective evidence over subjective opinions and interpretations.

I have enjoyed reading a number of books on him. I have close to a dozen.

He was encouraged by a few cardinals to advance the Copernican theory, especially since Galileo debunked the Aristotle/Ptolemy/Thomist model. As you said, some refused to look through the little scope as they failed to appreciate its accuracy, though testing it was not that hard. The debunking of the Geocentric model was hard to swallow, and it was in violation to clear dogma from the Council of Trent, IIRC. So, like politics today, religion got in the way of science.

The Jesuits, surprisingly, were quick to accept his debunking of the Ptolemy model, and he was highly respected... until things started going sour. Initially, there were a number who highly resented Galileo, and these numbers mulitplied, especially when he poked fun at the Pope's views in one of his important books.

He was a bit of a bully, but I've learned that his rough writing style was not that uncommon during that period. Nevertheless, narcissism does no one any favors. It certainly has never helped me much. ;)
 

ASK THE COMMUNITY

TRENDING THREADS

Latest posts