On 2021-01-12 09:41, Steve Allen wrote:
On Tue 2021-01-12T08:09:58-0700 Jonathan Leffler hath writ:
There were a number of articles about a week ago with some details about the amount by which the earth is spinning faster.
One such is: https://www.space.com/earth-spinning-faster-negative-leap-second.html
That appears to be a report from Live Science — I've not tracked down the original.
On Tue, Jan 12, 2021 at 7:57 AM Koning, Paul <Paul.Koning@dell.com> wrote:
Yes. The other point, though, is that leap seconds lengthen the day. In theory we can have omitted seconds, in practice we have not had those. The article speaks of the days getting shorter. Is there any data that supports this assertion?
Apologies, I forget that not everyone is running weekly cron jobs that interrogate the ongoing publications of IERS bureaus in order to track earth rotation. It has been faster during 2020, but not enough that a negative leap second looks likely. Still, predicting the weather in the earth's core is hard, so it is not impossible.
The original impetus for the articles was almost certainly Time and Date dot com who have been running an ongoing page of the IERS numbers with sports statistics about how fast the earth is rotating. See https://www.timeanddate.com/time/earth-rotation.html and their year end summary at https://www.timeanddate.com/time/earth-faster-rotation.html
It looks like a reporter for a UK newspaper picked up on that and interviewed Peter Whibberley of NPL in order to start the sequence of bots reproducing the original and other reporters rephrasing.
Not too unusual as the last long gap was 7 years between 1999 Jan and 2006 Jan. One problem may have been that the last leap second was declared when dUT1 was changing rapidly but 6 months later had reached only about -0.4 in 2017 Jan, when the leap second flipped it to about +0.5, dUT1 kept going down to -0.1 around 2019 Mar, and it's wobbled between that and -0.25 since then; see: https://datacenter.iers.org/data/latestVersion/224_EOP_C04_14.62-NOW.IAU2000... and predicted to stay around there for the next year at least: https://datacenter.iers.org/data/latestVersion/6_BULLETIN_A_V2013_016.txt when it will be only 5 years since the last leap second: long enough for some people to start forgetting again about accounting for leap seconds in timekeeping code, so that more systems may have issues the next time a leap second is added; cue comp.risks/risks@csl.sri.com. -- Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada This email may be disturbing to some readers as it contains too much technical detail. Reader discretion is advised. [Data in binary units and prefixes, physical quantities in SI.]