Calling all cosmologists...

[Blackheart]

Can anyone tell me why the Oort Cloud is a cloud and not a belt...

My 'limited' understanding of the origin of the solar system is that it formed from a vast cloud of interstellar gas and dust. The cloud began to collapse under its own gravity and, according to chaos theory, this would always lead to rotation. Thus we have protostellar disks from which the planets, comets, and asteroids slowly form.

We have the planets, orbiting along a similar plane, we have the asteroid belt and the kuiper belt... So why, if it all formed from one big rotaing cloud, why did the Oort cloud form a cloud and not a belt lying in the same plane as everything else?

If anyone can shed light on this I would really appreciate it. I struggle at the best of times but I am always trying to understand just a little bit more...

Many thanks

Blackheart

[glowjet]

When I came across this I envisaged the Oort Cloud as irregular with no defined limits, whereas the Kuiper Belt and the Asteroid Belt are bands with defined limits, I am no Cosmologist, but came to this conclusion, whether rightly or wrongly, in order to try and understand it.

[George Jones]

The composition of comets indicates that the comets probably formed between the orbits of Uranus and Neptune, likely in the disk of the forming solar system. Their orbits were altered by gravitational encounters with the gas giants. These encounters scattered the comets into a wide variety of orbits. The radius of the Oort cloud is almost 20% of the distance to the next nearest star, so encounters (over millions or billions of years) with passing stars further randomized the orbits of the stuff in the Oort cloud. All these interactions with planets and stars produced a roughly spherical shape for the cloud.

[Blackheart]

Thanks George

A great explanation and in one fell swoop I undertsand!

Cheers

Blackheart

[glowjet]

Thanks George, had not quite understood it would have formed into a a sphere.

[themos]

Intuitively, you need a lot of energy to get there from here. High energy states have more configurations available to them so you expect them to be more random.