Caption: The night sky looking toward Polaris in a long-exposure image from Ehrenbuerg, Bavaria, Germany.

Features:

1. The exposure time was about 45 minutes. This means the star trails will be about (15 degrees/h)*(3/4 h) &cong 11° as measured from the north celestial pole (NCP). This does NOT looks quite right. It looks like ∼ 5 star trails cover 90^deg; which which means each is ∼ 18°. But maybe the eye deceives yours truly.

2. From such an image, it is easy to understand how some of the Presocratic philosophers of ancient Greece came to believe that the Earth was a rest inside a cosmic vortex.

3. Polaris is within 1° of the NCP, and so to casual observation does NOT seem to move at all. In the image, it is on the axis of the "cosmic vortex". (Polaris actually revolves on a very small small circle on the celestial sphere every day.)

   Because it is so close to the NCP, Polaris is the Northern Hemisphere pole star of our historical period.

   For Northern Hemisphere observers, it is always just hanging there at nearly the same place in the sky, but you can't see it during the daytime.

4. Star trail videos (AKA Star trail videos):
   
   1. The motion rotation of stars around Polaris star | 0:49: Polaris is the pole star in the northern sky and makes only a small circle around the north celestial pole (NCP). Note the diurnal rotation is (counterclockwise looking north.
   2. North Celestial Pole Star Rotation | 0:59: Same comments as for item 1.
   3. Southern Celestial Pole timelapse | 1:09: Note the south celestial pole (SCP) has NO pole star and the diurnal rotation is clockwise looking south.