Measuring Earth's Orientation with Very Long Baseline Interferometry

David Boboltz of the US Naval Observatory talks about how radio telescopes are used to measure climate change indicators and the shifting of Earth's crustal plates.
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Additional animation and video credits: J. Hellerman and A. Angelich; NRAO/AUI/NSF; Neil Stratford - The Earth's Tilt Motion Graphic www.neilstratford.ca/; NASA Earth Observatory image by Robert Simmon, using Suomi NPP VIIRS data provided courtesy of Chris Elvidge (NOAA National Geophysical Data Center). Suomi NPP is the result of a partnership between NASA, NOAA, and the Department of Defense; NASA Goddard Space Flight Center Image by Reto Stockli (land surface, shallow water, clouds). Enhancements by Robert Simmon (ocean color, compositing, 3D globes, animation): NASA/Goddard Space Flight Center; Google Earth; USGS.
Music: Geodesium

[@michaelbauers8800]

So which comes first, the chicken or the egg? Because to do this, we need to know what time each measurement is taken I presume. And atomic clocks, in theory, count seconds, but don't know what time it is, until we tell them. And it seems like VLBI could allow us to tell time, by knowing exactly when the prime meridian is pointed directly at the sun, so we would know when UTC noon is. But then it seems like we have to accurately know the time to use VLBI to know the time. Hence my confusion.