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Radiation has become a boogeyman. It’s like UV light from the sun. We all experience it. Some places more than others. But it’s not certain cancer if you go to a place with higher radiation. It’s 0.05% more cancer if you hang around all year.

tbf when you're dealing with orders of magnitude a 5x difference is practically a rounding error

As the other commenter said, rotation of clouds is just the net effect of the orbits of their components. This is just speculation on my part, but I suspect the Hills cloud shows more rotation, because the objects that make it up are closer to their original orbits. It would also be rotating faster because it is more compact. In the outer cloud, I suspect there’s some small net rotation, but largely the velocities and orbits are randomly distributed so there’s less bulk movement.

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The Sun's gravity scoops up debris from the interstellar medium. I bet some of it gets captured in the Oort cloud.

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I suspect elliptical galaxies are the merger of galaxies where the collision canceled out both galaxies rotational energy.

It's not really a properly defined question because there's no single good definition we can apply for "back to normal" if you mean "when did fern spores get more common than fungi and the light levels return to normal again" (a few years) the result is very different than "when did the 80 tonne herbivores and 8 tonne predators re-evolve?" (66 million years and counting).

IIRC it took something like 5-10 million years to get any mammalian herbivores over 500 kg coming back.

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Not drag from friction, but gravity is what i meant. The same effect that causes the moon to face earth.

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