Fixed stars

Fixed stars (from the Latin stellae fixae) are celestial objects that do not seem to move in relation to the other stars of the night sky. Hence, a fixed star is any star except for the Sun. A nebula or other starlike object may also be called a fixed star. People in many cultures have imagined that the stars form pictures in the sky called constellations. In ancient Greek astronomy, the stars were believed to exist on a giant celestial sphere, or firmament, that revolved around the Earth daily.

Fixed stars do have parallax, which is a change in apparent position caused by the orbital motion of the Earth. This effect was small enough to not have been noticed until modern times. It can be used to find the distance to nearby stars. This motion is only apparent.

The fixed stars exhibit real motion as well, however. This motion may be viewed as having components that consist in part of motion of the galaxy to which the star belongs, in part of rotation of that galaxy, and in part of motion peculiar to the star itself within its galaxy.