Definition: Astrometry: Astrometry is the science or art of precise measurement of the position of astronomical objects and motions of celestial bodies. Astronomical observations of nearby stars is a proposed technique for measuring the small "wobble" of the star caused the unseen companions, such as extrasolar planets.
While astronomy may be the oldest science, astrometry can be considered the oldest sub-field of science. Because navigators used to calculate their position on Earth upon the observation of stars, astrometry has been important in history for sailing.
Modern astrometry is more often used for measuring time. The international time standard is the Coordinated Universal Time (UTC), that is basically the atomic time synchronized to Earth's rotation by means of exact observations.
Also Known As: Positional Astronomy