Here we see a sequence of star trails, also known as star strokes or stellar rotation. These types of images are very popular among astrophotography fans. The effect is achieved through prolonged exposure.
With this technique the apparent movement of the stars in the sky is captured. The rotation of the Earth creates the false appearance that it is the stars that rotate in the sky throughout the night. We can do the test. If we take the northern hemisphere as a reference, we must place the celestial north pole, very close to the Polar Star. This central point will remain in the same place throughout the night.
Circumpolar stars do not come out or set, but will always be above the horizon. As the hours pass, it will appear that they revolve around the center point, counterclockwise.
The stars furthest from the center point will have a wider turning path, will not be observed throughout the night and will disappear on the horizon.
If we do the test in the southern sky, on the other hand, the sky will appear to revolve around the celestial south pole in the same direction as the clockwise.
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