Why do stars twinkle?

I have always had a pretty good idea why stars twinkle and planets emit a solid beam of light, but I wanted to know the specifics. So, here is a general overview. Enjoy the simplicity.

Stars twinkle because of out atmosphere distorting their image from Earth. Furthermore, as the gases that make up our atmosphere churn, the light from the stars fluctuates and moves slightly resulting in a twinkle. The lights from the stars that we see are not the finite edges of the stars surface but are the light that the stars emit that is obscured by the vast distances and space particles that lie between us and the stars. Obviously, this is why the best images of the stars are taken by telescopes in space.

So, why are planets easy to identify from stars? Man, that is simple. The finite, unwavering image that a planet emits is able to "average out" the turbulent effects of the atmosphere and produce a solid beam of light that appears more stable than that of the stars.

Reference: http://curious.astro.cornell.edu/question.php?number=114