[LEAPSECS] Reliability

[Zefram]

Tony Finch wrote:

>(Um, do we actually know the earth's angular momentum and moment of

>inertia to any useful accuracy?


Our knowledge of the planets' masses is limited.  From watching orbits
we know very precisely the product of each planet's mass with the
gravitational constant.  But we only know the gravitational constant
itself to about five significant figures, and so we don't know the
absolute planetary masses any more precisely than that.  This imposes a
limit on our knowledge of angular momentum, and many other quantities that
have to be derived by multiplying a directly-observed quanity by mass.

-zefram