[tz] Earth's day lengthens by two milliseconds a century
eggert at cs.ucla.edu
Fri Dec 9 02:14:54 UTC 2016
On 12/08/2016 03:45 PM, Steve Allen wrote:
> Except that Morrison and Stephenson and Hohenkerk only show the past.
> NASA polynomials attempt to predict the future, but (as seen in the
> data of this new publication) to their peril.
Yes, the Stephenson et al. paper is newer and presumably more
authoritative and 'Theory' cites it first. I assume Espenak will update
the other page eventually, and in the meantime it's an entertaining set
The 'Theory' file cites these two sources only to support the statement
that we don't know historical solar time to more than about one-hour
accuracy, a statement that I hope is vague enough to pass muster. If we
wanted to get picky, we'd have to determine what's "historical": back to
3200 BC? or back to the earliest reliable astronomical records? if the
former, we don't have even one-hour accuracy; if the latter, it depends
on one's definition of "reliable". Still, the statement is in the right
ballpark, which is all that's needed there.
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