We inhabit a system with significant angular momentum:
http://www.zipcon.net/~swhite/docs/astronomy/Angular_Momentum.html
If our solar system formed by gravity gathering its material together to form the sun, proto-planetary disc, and eventually the planets, which all orbit in the same direction…
Where did this angular momentum come from in the first place, since angular momentum is conserved?
It does not seem possible to me that the formation of the solar system under gravity could impart this angular momentum on it, if it is a closed system. If it formed from a 'cloud of space dust', then it must have been present in that dust cloud, but where did the dust cloud get it from?
Best Answer
A collapsing gas cloud is an open system. It loses mass, energy and angular momentum as it collapses. Even if the net angular momentum of the cloud is zero, after the collapse the final planetary disk can have a significant net angular momentum, and the ejected material will have the opposite angular momentum. What can not happen, and that's where your intuition is correct, is that all the material in the original cloud collapses into the disk while rotating in the same direction.