Why is Uranus on its Side?

It was a well done explanation. Enjoyed it--as usual.

Can you recommend any beginner level books that discuss the mechanics of planet and star formation? I have so many questions, like why doesn't all the matter in the gas cloud collapse into a star? Related to that, what determines how much matter coalesces into a planet? Why don't all planets have rings? Do stars have rings? Why don't gaseous planets fly apart, especially given their high rate of rotation? Can Dark Matter form celestial objects? Thank you for another fascinating video!

How is it possible to collide with a gaseous sphere? If it's impossible to stand on it, how is it possible to impact it and perturb its orientation?