[LEAPSECS] 1.26 microseconds

[Rob Seaman]

On Jun 13, 2011, at 2:18 PM, Poul-Henning Kamp wrote:


> In message <96366060-430F-451B-81CC-D63082CD971F at noao.edu>, Rob Seaman writes:

> 

>> So "day" is a word referring to Earth Rotation?

> 

> As a first order approximation, the same way a year is a first order

> approximation to earth orbital position.


Does "first order approximation" mean stationary over long periods of time?

Note, of course, that no such language is in the ITU draft.


> Poul-Henning

> 

> PS: I read an interesting note recently about how the fact that

> years have varying lengths have become an issue for determining the

> "official" half-life of long lived radioactive isotopes:  Many

> geological methods just counted years, but hadn't considered how

> long those years were.


Reference?  Length-of-day varies in the rich and wonderful ways we've discussed, lo these many years.  If variation of length-of-year is a significant issue it has not been stated previously in this context.

Rob