Exploring the Possibility of the Oort Cloud

In summary, the Oort cloud is a spherical area of space at the edge of the Solar System where long-period comets are thought to originate. The Oort cloud is a speculative idea based on the trajectories of comets, and there is still some uncertainty about its existence.
  • #1
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I know this has been suggested because of long period comets.
Sort of a spherical asteroid belt at the very edge of where the Sun's gravity has any relevance.
The inner asteroid belt, and the Kuiper belt though have many examples of objects which are proof that they exist.
Is the Oort cloud any more just fairly reasonable speculation?
 
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  • #2
The main evidence for the existence of the Oort cloud s the trajectories of comets.

from wikipedia
In 1932, the Estonian astronomer Ernst Öpik postulated that long-period comets originated in an orbiting cloud at the outermost edge of the Solar System.[7] The idea was independently revived by Dutch astronomer Jan Oort as a means to resolve a paradox.[8] Over the course of the Solar System's existence the orbits of comets are unstable and eventually dynamics dictate that a comet must either collide with the Sun or a planet or else be ejected from the Solar System by planetary perturbations. Moreover, their volatile composition means that as they repeatedly approach the Sun, radiation gradually boils the volatiles off until the comet splits or develops an insulating crust that prevents further outgassing. Thus, Oort reasoned, a comet could not have formed while in its current orbit and must have been held in an outer reservoir for almost all of its existence.[8][9][10]

There are two main classes of comet, short-period comets (also called ecliptic comets) and long-period comets (also called nearly isotropic comets). Ecliptic comets have relatively small orbits, below 10 AU, and follow the ecliptic plane, the same plane in which the planets lie. All long-period comets have very large orbits, on the order of thousands of AU, and appear from every direction in the sky.[10] Oort noted that there was a peak in numbers of long-period comets with aphelia (their farthest distance from the Sun) of roughly 20,000 AU, which suggested a reservoir at that distance with a spherical, isotropic distribution.[10] Those relatively rare comets with orbits of about 10,000 AU have probably gone through one or more orbits through the Solar System and have had their orbits drawn inward by the gravity of the planets.[10]
 
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What I find disturbing is the fact, that we think the Oort Cloud exists and is still related to our sun, but this doesn't prevent us from calling the Voyagers' current positions interstellar at about 111 AU, 135 AU resp. It will take them another 6,000 years to reach it (20,000 AU assumed).
 
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  • #4
I can see where the reasoning comes from.
However is it not possible that very long period comets are just small bits of interstellar material that never were part of the solar system, or any other system, just loosely bound frozen gases (including water)
(Not a personal theory, just a question)
 
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fresh_42 said:
What I find disturbing is the fact, that we think the Oort Cloud exists and is still related to our sun, but this doesn't prevent us from calling the Voyagers' current positions interstellar at about 111 AU, 135 AU resp. It will take them another 6,000 years to reach it (20,000 AU assumed).
It's called interstellar space because that's where the interstellar winds are dominate. The sun becomes as insignificant as every other star. The Oort cloud is only bound to the sun because it's the closest strong source of gravity, other than that, it's essentially an interstellar object, the sun has no effect on it.
 
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  • #6
rootone said:
I can see where the reasoning comes from.
However is it not possible that very long period comets are just small bits of interstellar material that never were part of the solar system, or any other system, just loosely bound frozen gases (including water)
(Not a personal theory, just a question)

If comets were falling in from interstellar space, you would expect most of them to have eccentricities greater than 1, indicating that they are not bound to the solar system. In practice I think (not sure) that most long period comet eccentricities are less than 1, or at most equal to 1 within experimental uncertainty.
 
  • #7
Thanks everyone.
 
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1. What exactly is the Oort Cloud?

The Oort Cloud is a hypothetical spherical cloud of icy objects located in the outermost reaches of our solar system, extending from about 2,000 astronomical units (AU) to 100,000 AU from the Sun. It is thought to be the source of long-period comets that occasionally enter the inner solar system.

2. How do we know the Oort Cloud exists?

While we have not directly observed the Oort Cloud, its existence is supported by mathematical models and observations of long-period comets. These comets have highly elongated orbits that can only be explained by their origin in the Oort Cloud.

3. What is the significance of studying the Oort Cloud?

Studying the Oort Cloud can provide valuable insights into the formation and evolution of our solar system. It can also help us understand the potential impact of comets on Earth and other planets, and potentially provide clues about the formation of other planetary systems.

4. How do scientists explore the possibility of the Oort Cloud?

Scientists use a variety of methods to explore the possibility of the Oort Cloud, including mathematical models, astronomical observations, and spacecraft missions. They also study the chemical composition and physical properties of comets to gather more information about their origins.

5. Are there any ongoing or planned missions to explore the Oort Cloud?

Currently, there are no specific missions dedicated to exploring the Oort Cloud. However, NASA's Voyager 1 and 2 spacecraft are expected to reach the outer edge of the Oort Cloud in the coming decades. Additionally, the European Space Agency has proposed a mission called "Comet Interceptor" which aims to study a comet from the Oort Cloud in the future.

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