Oort Cloud and Kuiper Belt: differences

[sophiecentaur]

When I read about formation of solar systems it seems reasonable to me that most of the material would end up lying in a plane because the number of collisions and interactions would be least and the most stable situation in a common orbital plane in the long run. (Is this a far too simplistic notion?) The axis of this plane would, presumably be the axis of the net angular momentum vector of the original nebula from which the system was formed as any orbits away from that plane would have net zero angular momentum.

The Kuiper Belt seems to be part of this plane but the Oort Cloud seems to be more spherical. Why would this be? Is the Oort Cloud so far away and such low density that this sorting out mechanism would take much longer than 4 billion years, which was enough to give us our familiar solar system layout? The Oort Cloud is at least one hundred times further out than the Kuiper Belt so settling down time could be much longer as things must have very low orbital speeds out there.

 

[Baluncore]

There is a planar inner Oort cloud, and a spherical outer Oort cloud.
The Oort clouds are "theoretical".
https://en.wikipedia.org/wiki/Oort_cloud
https://en.wikipedia.org/wiki/Hills_cloud

The Kuiper belt is not theoretical, but real, with a list of members.
https://en.wikipedia.org/wiki/Kuiper_belt

 

[sophiecentaur]

The Oort clouds are "theoretical".

Right. Thanks - so the "theory" must imply something about the mechanics of very large orbits which allows objects to 'stay' or 'arrive' in non planet-style orbits. Sounds reasonable and not unlike the picture that arrived in my brain.

It seems like the Kuiper and Oort objects would have many of the materials that we could find use for in future big expeditions. Not quite such ridiculous timescales needed to get there as stellar trips. The only thing missing would appear to be useful amounts of sunlight but in the future, it may not be as important to humans.

And that suggests that realistic ideas about colonisation could well involve the race changing to zero g tolerance. Sounds a bit dreary to me but how our descendants might feel about it could be very different. B ut I digress - returning to the thread . . . .

 

[Baluncore]

... changing to zero g tolerance. Sounds a bit dreary to me but how our descendants ...

With zero g, there is no up nor down, so no descendants.