The fixed stars (Latin: stellae fixae) compose the background of astronomical objects that appear not to move relative to one another in the night sky, unlike the foreground of Solar System objects, which appear to move. Generally, the fixed stars are taken to include all stars other than the Sun. Nebulae and other deep-sky objects may also be counted among the fixed stars.
Exact delimitation of the term is complicated by the fact that celestial objects are in fact not fixed with respect to one another. Nonetheless, extrasolar objects move so slowly in the sky that the change in their relative positions is nearly imperceptible on typical human timescales, except to careful examination, and so can be considered to be "fixed" for many purposes. Furthermore, distant stars and galaxies move even more slowly in the sky than comparatively closer ones.
People in many cultures have imagined that the stars form constellations, which are apparent pictures in the sky. In Ancient Greek astronomy, the fixed stars were believed to exist on a giant celestial sphere, or firmament, which revolves daily around the Earth.
https://en.wikipedia.org/wiki/Fixed_stars
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