Photography gives us the chance to discover a wonderful that usually we don’t notice: Earth movement.
Stratrails reflect Earth’s rotation movement, that is faster than most of us think (460 m/s). As you see stars apparently lined with Earth’s axis (Polaris at North), you believe stars are moving around this point. It’s an optical effect. Actually stars move but not around Polaris.
You can see the Time Lapses linked to these pictures here.
Click to enlarge and scroll.