[LEAPSECS] Far past and far future

Rob Seaman seaman at noao.edu
Fri May 27 15:41:04 EDT 2011

Hi Richard,

> A more recent paper that might be of interest is "Lunar Core and Mantle. What Does LLR See?"

> http://cddis.gsfc.nasa.gov/lw16/docs/papers/sci_1_Williams_p.pdf

Very interesting...

> Although I was involved in LLR data analysis as a postdoctoral fellow at MIT between 1979 and 1981, I concentrated on the intra-annual variations in the length of day (and their association with changes in atmospheric angular momentum) rather than the decadal and longer variations. That work was written up in Nature.

> http://www.nature.com/nature/journal/v294/n5843/abs/294730a0.html

Nice picture of Anak Krakatau on the cover! (Good to have a library in the building.)

Note that the title, "Atmospheric angular momentum and the length of day...", raises the question of the definition of the word "day". Your paper's analysis combined data on "l.o.d." (clearly the measured length of the varying mean solar day - so obvious this definition wasn't even discussed) with measurements conducted at 0h and 12h UTC. Nobody would have thought twice to worry that these two sets of data might be tied to two divergent clocks in the future.

The proposal in front of the ITU seeks to pretend that length of day is a constant equal to 86,400 SI-seconds. This is nonsense.


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