Angular Motion

Not my best shot, but a must after my last post, where I wrote that star trails are caused by earth rotation (angular motion).

 

Of course any rotation of the camera will lead to circular star trails. You can therefore also rotate your mount to achieve the effect. That's what happened here when I initiated a turn with my flying mount.

 

You can see the turning path in the cloud cover below, while the roll caused the star trails.

 

EXIF

Canon EOS 6D astro modified

Samyang 24mm f/1.4

Mount: Boeing 777-300ER

10s @ ISO6400 f/2

Done