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Geodetic science (geodesy) is that branch of science concerned with determining the size, shape, and gravitational field of the earth, and precisely mapping its surface features. Astronomic observations provide essential information in the geodetic process. Both the earth-based observing stations and the observed extraterrestrial bodies (stars, planets, natural and artificial earth satellites) are in motion, creating time-dependent coordinate systems and making epoch, interval, and synchronization important. Modern geodesy uses the most sophisticated optical and electronic equipment in measurements, and the timing requirements have become increasingly stringent. Systems that require accurate timing often have potential in the determination of time. Lunar laser ranging, a currently developing technique with many exciting geodetic implications, may develop into a practical method for the determination of Universal Time (UT1) to a new order of accuracy.