Move the Stars

Try this: on a clear night, look up at the stars (you need to be able to fill most of your vision with the black night sky and stars). Look for a bright star like Polaris, the North Star, and focus on it. Don't blink. After a while, you should see only that star. Then what happens?

It moves.

It squiggles, it squirms, it goes up, down, left, right, in loops and all over.

Polaris, which is just light years and light years (and light years) away shouldn't move about like that. If it did, it would be moving faster than the speed of light and at your very whim.

So why does it happen? My theory is that once you focus on one star long enough your eyes start to defocus the rest of the starfield which is already fairly dim anyway. Pretty soon, you might as well have only one point of reference in your entire field of vision. But if that's true, then it's not really a point of reference because it is not related to anything else. You have one dot on a black field that doesn't indicate any kind of position. So your brain and eyes starts to go "huh?" and correctly assume that with so little information, that little dot can be anywhere. 30 degrees up, 50 degrees to the right, wherever. It doesn't know. So as you focus on it, it just kind of wanders around because Lord knows where Polaris is without the others stars to guide you. It can't wander too far away because if you don't focus on it everything else will come back into focus and it'll snap back. And if you do follow it then it will always remain around the approximate center of your vision anyway. Weird.