|fixed star |
A star or other celestial object so distant from Earth that its position in relation to other stars appears not to change over time. The fixed stars, which include virtually all visible objects beyond the solar system, form the background against which the motions of the Sun, planets, and other bodies of the solar system are measured, and they provide the reference for determining sidereal time. In actuality, no celestial object has a fixed position in relation to any other, and the movement of so-called fixed stars can be measured by precise observation over long periods of time. See more at proper motion.