Modern methods for the determination of polar motion and UT1

The applications and Doppler satellite observations, laser ranging to artificial satellites and the Moon, and astronomic radio interferometry to monitoring polar motion and Universal Time System 1 (UT1) are discussed. How and what each method is capable of measuring, fundamental limitations, and the present status of the developments of each method were reviewed. Evaluations of the various methods as candidates for the next generation international polar motion and UT1 monitoring service are summarized.