• The change in apparent position of an object caused by movement on the part of the observer. Parallax errors in reading a gauge are those caused by looking at it at an angle rather than from the front. The parallax of a star is the alteration in its position caused by the Earth’s annual movement in its orbit. Parallaxes were the first means of determining stellar distances, although the method only works for nearby stars.


  • The apparent displacement or change of direction of an object when viewed from different positions. In an indicating instrument for example, different readings may be obtained depending on the position from which the pointer is viewed.