Why do stars twinkle? (another factor)

[rowrrbazzle]

column http://www.straightdope.com/columns/...-stars-twinkle

There's another factor in the twinkling of stars. Because the path of the light from a star is slightly different for each eye, the star also twinkles differently as seen by each eye. You can see this by crossing your eyes slightly until you see two images of the star (or when at a window in a tall building, seeing sunlight glinting off some distant object). This adds to the effect of the simple variation of the light.

[ND Wind]

Stars twinkle because, due to their distance, their visible size is smaller than a single pixel (rod) of our (human) eye ... therefore the tiny light source 'dances' from pixel to pixel.