Astrometry is a branch of astronomy that studies to precise measurements and explanations of the positions and movements of stars and other celestial bodies. Although once thought of as a field with little useful application, the information obtained by astrometric measurements is now very important in contemporary research into the kinematics and physical origin of our solar system and galaxy.
The history of astrometry lies parallel to the past of star catalogs, which gave astronomers reference points for objects in the sky so they could track their movements. These catalogs can be dated back to around 300 B.C. These catalogs were first used to discover the Earth’s precession. Ptolemy published a catalog that included 1,022 stars. An ancient astronomer named Hipparchus used star catalogs to develop the brightness scale that is still used today.
This branch of astronomy has many practical applications in today’s world of science. Other than providing astronomers with a reference frame to report their observations in, it is also fundamental for fields like celestial mechanics, stellar dynamics, and galactic astronomy. Astrometric techniques help identify stellar objects by their unique motions for observational astronomy. It has been found to be instrumental in time keeping, because UTC is basically the atomic time synchronized to Earth’s rotation by means of exact observations. The field is also involved in creating the cosmic distance ladder(astrometry is used to establish parallax distance estimates). It has also been used to support extrasolar planet detection by measuring the displacement that the proposed planets cause in their parent star’s apparent position on the sky.
Try the NASA webpage about an application for astrometry. Here on Universe Today we have a great article about a triumph in the field. Astronomy Cast offers a good episode about going in search of new worlds.
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