“Star Trails” or Circum-Polar photography
Behind this all-scientific name hides is a rather clever spectacular photography technique. It highlights the rotation of the earth around the Polar Star.
The method is simple; leave a “reflex” type camera – in long exposure for purists, or short for computer specialists – and see the displacement appear in the sky around a single point, the polar star towards which the axis of rotation of the earth is oriented. Then, simply stack each photo in dedicated software or a simple “PhotoShop”. And by magic, it appears the splendid lines that the colored stars leave on dark sky.
A short video for a better understanding of the thing: