The sky is not the limit for producing artistic compositions. Normally, these star trails are created as the Earth rotates on its axis, with the center being close to either Polaris, the north star, or the Southern Cross, depending on which hemisphere you are in. Space Station makes one revolution every 90 minutes (the Moon takes 28 days). As a result, long-exposure pictures taken from the Station show star trails as circular arcs, with the center of rotation being the poles of Space Station (perpendicular to our orbital plane.)
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