I'm taking an astronomy class in college and I'm loving it and I find it very interesting.

We're pretty deep into the course now, but strangely enough, we never came across this question.


Why do planets rotate? I know they revolve around the sun because of gravity, but why do they rotate? and why do they rotate a certain direction?

I tried googling for some answers, but I was still not very clear on the reason other than the fact that it has to do with physics..

http://curious.astro.cornell.edu/question.php?number=416

found some interesting information there.

I see...

that is interesting

conservation of angular momentum. thats why neutron stars rotate several hundred-thousands of rotations per second. a huge star that rotates slow condenses to a 10-50km size star and makes it rotate incredibely fast

I'm pretty sure the mystery lies as to the source of the original angular momentum. Why in the first place did planets start rotating when they formed?

Did you really ask that question? Did you not cover it in "Physics I" in high school?

If I were you, I wouldn't question other people's education, with your senior thesis being like this

http://forums.d2jsp.org/index.php?showtopic=30450208&f=266

He asked because we all know it's because Planets get bored easily, but he wanted to double-check.

We don't even have a physics "i" in our high school....I am taking AP Physics C however.

Forces acting on planets aren't all perpendicular to its axis of rotation, which generates angular velocity.

Planets all have forces acting on them.. Space debris, gravitational forces from moons, etc

Our moon slows down the earth's rotation.