500 Rule, Left Brain Thinking!

We have a problem. The earth is rotating! It's making the stars in our astro images blurry!!! Don't worry, we have a solution. There is a simple rule to follow to avoid these streaky stars. Don't get me wrong, star trails can make some really cool images but what if you want to get that tack sharp shot of the Milky Way? FYI- Right now is prime time for MW images in the northern hemisphere. Here is where the rule comes...