Hi Adam,
> I've read several articles lately claiming that the Earth is spinning
much
> faster since 2020.
Yes, quiet, then many articles in a few days, then quiet. It's been
fascinating to see how technical news morphs and scary how fast it
spreads. Some of the headlines are creative to the point of sensational.
> I didn't see anything definite directly from IERS about this,
That's because there isn't much to say. IERS creates data. They do it
very well. At the millisecond level the earth is always quite variable
and you get used to it. There are always highs and lows, always cycles,
trends, and predictions. The same as any oscillator. Earth is a clock
too. [1]
That said, there has been an uptick in postings on the LEAPSECS list the
past few years. [2] We have been watching earth rotation trends
carefully since the last time this happened, back in 1999-2006, when
there was no leap second (not positive, not negative) for a record
breaking 7 years. It might happen again. You can get the same excitement
watching GPS sawtooth error unfold before your eyes. ;-) By analogy the
Earth seems to do a hanging bridge every ~20 years.
> but I was wondering if the systems are ready for a negative leap
> second some time in the future?
Of the recent news articles, the more prudent ones are quick to point
out that this does not mean there will be a negative leap second. The
only observation right now is that the earth, on average, is closer to a
true 86400 s day than in recent years or decades. It will take some time
before the actual outcome is known.
It takes a lot of sub-milliseconds before it accumulates enough to be
adjusted with a (positive or negative) leap second. As I mentioned, a
similar thing happened 20 years ago and it didn't lead to a negative
leap second. This time it might. Or might not. I would not bet on the
Earth; there are so many factors involved, many of which are deep inside
the planet and there isn't a lot of understanding at that level.
As far as negative leap seconds, its useful to remember that UTC, from
day one, was designed to handle either +1 or -1 corrections at the end
of a month. Most of the systems I know are fine either way, or a problem
either way.
That said, and to address your comment, I'm sure there will be s/w bugs
here and there; that is the nature rare events like leap seconds. It's
also one reason why there is serious consideration to just get rid leap
seconds altogether, but that's a topic for [2].
/tvb
[1] http://leapsecond.com/museum/earth/
[2] https://pairlist6.pair.net/mailman/listinfo/leapsecs
On 1/9/2021 3:56 AM, Adam Kumiszcza wrote:
Hi.
I've read several articles lately claiming that the Earth is spinning much
faster since 2020. I didn't see anything definite directly from IERS about
this, but I was wondering if the systems are ready for a negative leap
second some time in the future?
https://phys.org/news/2021-01-earth-faster.html
Adam
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