No leap second will be introduced at the end of December 2026
106 points
1 hour ago
| 12 comments
| datacenter.iers.org
| HN
bombcar
1 hour ago
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"To authorities responsible for the measurement and distribution of time" is just the best preamble ever.
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flexagoon
1 hour ago
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The only better thing is the organization being called "International Earth Rotation Service"
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nullorempty
1 hour ago
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Oh boy :) I think that would come with IERS Tax.
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kevin_thibedeau
56 minutes ago
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You have to go to the ends of the earth to cancel.
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summarybot
24 minutes ago
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The real problem is finding the antipodal help desk without digging.
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CommieBobDole
51 minutes ago
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For many years, the title of the leadership role over the various precise time products at the USNO was "Director of the Directorate of Time"
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MengerSponge
7 minutes ago
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Do they have an insignia or patch? Can we buy it?
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steve1977
1 hour ago
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Sounds like something out of a Douglas Adams novel.
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tetris11
51 minutes ago
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Or XKCD. I love patch day.
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danbruc
30 minutes ago
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declan_roberts
58 minutes ago
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"Director Earth Orientation Center of IERS Observatoire de Paris, France"

Even the titles are sci-fi.

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404mm
31 minutes ago
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“Time Lord” could have been used instead of Director. At least once. Please.
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srdjanr
1 hour ago
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They should call themselves Time Lords
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ninju
32 minutes ago
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For those who need more context of who the Time Lords are

The Time Lords are a fictional ancient race of extraterrestrial people in the British science fiction television series Doctor Who. In-universe, they hail from the planet Gallifrey and are stated to have invented time travel technology.

https://en.wikipedia.org/wiki/Time_Lord

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dotwaffle
40 minutes ago
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Traditionally, that was the email address for the NTP service at various organisations, in the same way that postmaster was for the mail service.
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doctoboggan
1 hour ago
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What causes the unpredictability in this? I would have guessed we have earth's rotation and orbit down to many decimals. Does geological activity, weather, or something else cause rotation speed differences that we just can't predict?
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_alternator_
47 minutes ago
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In short, yes, the weather, geology, and signicantly, human movement of water via aquifer draining and dam building, as well as glaicial and ice melts, all contribute to unpredictable changes in the earths rotational period, as well as the axis of rotation. The models for this are IIRC trigonometric polynomials of fairly low order, so even if we could model the unpredictability perfectly, truncation error would limit our ability to distribute the model at super high accuracy. The existing models are built in to, eg, satellites, so you can't just make them arbitrarily complex.

Fun fact: leap seconds will stop being a thing soonish. I think they phase out in 2035, with a delay because Russia needed time to update glassnoss satellites.

(Note: on mobile, this is from memory, details need checking ;))

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tialaramex
27 minutes ago
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2035 is the agreed drop dead date.

Everybody agreed that "Leap seconds" are a sufficiently bad idea that they should be replaced by 2035. Nobody has agreed how to fix it, and "Just turn them off" isn't technically legal. However, "What if there were Leap hours instead?" is technically legal and of course those hours would happen in the very distant future (likely after our civilisation is gone) so it's functionally identical to "Just turn them off" but without legal problems.

Now, I'm English, and England loves this sort of hack. You may have heard that controversial UK politician Nigel Farage "resigned" as a Westminster MP recently and that's not technically true because you can't resign, historically people hated that job and so you can't resign and we never changed that, but what you can do, and everybody does, is get assigned an "Office of profit" in which legally the King is paying you, an MP can't work for the King so you can't be an MP any more. The "Offices of profit" in question aren't real jobs† and don't pay real money, like this "Leap Hour" they'd be a legal fiction. So everybody says you "resigned" but in fact you legally can't do that...

† I mean, historically they were real jobs that made sense which is why the King paid somebody to do them, but England is very, very old so they haven't made sense for centuries and serve only as a legal fiction today.

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jeffrallen
7 minutes ago
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[delayed]
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thewebguyd
27 minutes ago
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> as well as the axis of rotation

A frightening fact, the 2011 magnitude 9.0 Tohoku Earthquake shifted the position of the Earth's figure axis about 17 centimeters, making days about 1.8 microseconds shorter.

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lloeki
19 minutes ago
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> Russia needed time to update glassnoss satellites

GLONASS maybe? or really glasnost era satellites?

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entrope
53 minutes ago
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Yes, all of those and more. Our measurement precision is much better than the year-to-year first and second derivatives of day length. https://datacenter.iers.org/singlePlot.php?plotname=Bulletin... has the most relevant plot to this; the vertical jumps reflect leap seconds. (IERS has other plots for other dimensions of rotation, but I like this one.)
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doctoboggan
49 minutes ago
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Very interesting, I wonder what happened in 2020 that causes the rotational speed to start drifting the other way?

Pandemic -> more people working from home -> less people in tall office buildings -> faster rotation (like a skater pulling in their arms).

Probably not remotely true but it would be funny.

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wongarsu
37 minutes ago
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Seems like the seasonal change in June-October increased

My best guess would be it's somehow related to water distribution? More water going into the atmosphere? Glaciers growing (unlikely)? Did multiple huge water reservoirs go into service and get filled up over the summer months?

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flohofwoe
56 minutes ago
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Since I was checking the Wikipedia article anyway (for when the last leap second was inserted), it also has an answer for this:

"Because the Earth's rotational speed varies in response to climatic and geological events, UTC leap seconds are irregularly spaced and not precisely predictable."

https://en.wikipedia.org/wiki/Leap_second

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moi2388
54 minutes ago
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Yes. Geological activity, movement in the outer core, atmosphere, oceanic currents, melting ice, earthquakes, to name a few.

Earths rotation has been unusually fast lately. So there is not enough drift to warrant a leap second.

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KboPAacDA3
9 minutes ago
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If the UTC-TAI offset remains at -37s, then it also means the UTC-GPS offset remains at -18s. TAI and GPS have a constant 19s offset from each system.
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delichon
1 hour ago
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Hear me out. We can just mount jet engines along the equator and rotate them 180 to gain or lose time. And then connect them to my snooze button.
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dylan604
24 minutes ago
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Wouldn't it just be easier to have Superman fly around the planet a bunch of times really fast to do the same thing? Then you wouldn't have to worry about having to deal with all of that engine maintenance.
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gumby
37 minutes ago
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The problem is future societies harvesting the engines for interstellar probes. This problem has been discussed in a series of books by Larry Niven.
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tenthirtyam
23 minutes ago
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There's a graphic novel by Cixin Liu "The Wandering Earth" where they not only stop Earth's rotation with this method, but also propel Earth out of the solar system (for what appear to be good reasons, I might add). Can't quite remember what fuel they used for the engines.
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Polizeiposaune
23 minutes ago
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It would appear that this has worked as they haven't had to insert leap seconds for quite a while.
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flippyhead
35 minutes ago
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I feel like we can all just jump at the same time. I mean, we only need a second or two, right?
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ninju
30 minutes ago
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Well...we would all have to be at the same spot so that we don't cancel each other out. But that would come with its own challenges

https://what-if.xkcd.com/8/

(oh and it wouldn't be strong enough to affect the Earth's rotation)

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t1234s
1 hour ago
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They should have a global holiday to celebrate the people who maintain time/date related code in OS kernels that keeps the world from imploding.
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ortusdux
36 minutes ago
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I like the argument that we should have 12 months that are exactly 30 days long, and then merge whatever is left into a single timeless holiday.
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tialaramex
13 minutes ago
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raverbashing
13 minutes ago
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Lol the Kernel is "easy" it's userspace and distributed systems that are a b*tch
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radomir_cernoch
56 minutes ago
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Lol. Exactly!
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returningfory2
1 hour ago
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As one HN comment said years ago: I feel leap seconds have always lived in the wrong abstraction layer.

They should live in the same abstraction layer that does leap days and daylight savings: the time zones.

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thwarted
52 minutes ago
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Leap days, February 29th, are not at the level of time zones. Different time zones do not disagree as to when March 1st will occurs immediately after February 28th.
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stvltvs
50 minutes ago
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The changes in Earth's rotational speed that leap seconds help account for affect the whole globe. Why shouldn't the effects be noted in the global time standard?
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returningfory2
36 minutes ago
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Same with leap days though?

The point is that it's weird that we handle a day every 4 years off in a different way to a couple of second being off.

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wongarsu
25 minutes ago
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Don't we handle them mostly the same? In a leap year, the month of February gets a 29th day, labeled 29. On a leap second, one of the minutes gets a 61st second, labeled 60. Or we drop the 60th second, and second 58 is followed by second 00 of the next minute.

The notable differences are that

1) the leap second happens at the same time globally (23:59:60 UTC), while leap days start at 00:00 local time

2) leap seconds happen at irregular intervals

3) leap seconds are nearly universally implemented wrong, because the ability to show :60 on a second display for for one second at most twice per year is just not worth the implementation complexity

You could argue about 1, but the alternative would lead to much more complicated timezone math (time zones can be an additional one second apart from each other depending on whether the leap second is already applied) for very limited benefit. Number 2 seems unavoidable, and 3 is entirely unintended, just the way things have worked out in real life

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babypuncher
18 minutes ago
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Leap days are predictable whereas leap seconds are not.
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RugnirViking
51 minutes ago
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god that would be awful. Can you imagine time zones being one second off from each other. Or two or three? ah yes, india is GMT+4:30:03, where europe is GMT+0:59:58
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exegete
1 hour ago
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> The difference between Coordinated Universal Time UTC and the International Atomic Time TAI is :

>

> from 2017 January 1, 0h UTC, until further notice : UTC-TAI = -37s

This means the atomic clock is behind the solar clock by 37 seconds? I also don’t understand the reference to 2017.

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pdonis
31 minutes ago
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> This means the atomic clock is behind the solar clock by 37 seconds?

If anything, it's the other way around.

A UTC day is defined as exactly 86400 SI seconds. But an actual mean solar day is a few milliseconds longer (although the difference is not constant due to irregularities in the Earth's rotation--but the average difference is expected to slowly increase over time). SI seconds are counted by atomic clocks, so UTC advances its day by one every 86400 atomic clock seconds.

But a solar clock that advances its day by one every time the mean sun reaches noon (it has to be the mean sun because the rate at which the actual sun moves across the sky varies over the course of a year, we need to look at the average) will advance its day a few milliseconds later than UTC does. Or, to put it another way, each time period that the solar clock says is exactly 86400 seconds, is a few milliseconds longer according to the atomic clock.

As this happens day after day, the difference accumulates, and when it gets close to being a full second, a leap second gets inserted into UTC, so that one of its days is 86401 seconds long instead of 86400. The reason for this is that UTC is not just counting atomic clock time; it also has to stay in sync with where the sun is in the sky since so many human activities are tied to that. And we humans have defined "in sync with the sun" to be "within a second of the average sun". In other words, we want UTC noon to be within a second of mean solar noon on the prime meridian.

So the 37 seconds is how far mean solar noon would be behind UTC noon, if we didn't use leap seconds--at UTC noon, the mean sun would be 37 seconds short of actually crossing the prime meridian in the sky.

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Vvector
51 seconds ago
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"In other words, we want UTC noon to be within a second of mean solar noon on the prime meridian."

Why?

If I travel 1 mile east or west of the prime meridian, my solar noon now comes 2-3 seconds earlier/later. It's nearly impossible to have your local time match your local solar noon. For most of the population, solar noon is, on average, 30 minutes off of 12:00 noon.

Plus, solar noon varies from day to day by 10-20 seconds. Check the charts out. https://www.timeanddate.com/sun/usa/new-york

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flohofwoe
58 minutes ago
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Apparently December 2016 was the last time a leap second was inserted, at least that's what Wikipedia says:

https://en.wikipedia.org/wiki/Leap_second

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NooneAtAll3
48 minutes ago
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we were ought to insert a negative leap second, but cowards got too afraid it would break code
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doctoboggan
1 hour ago
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> I also don’t understand the reference to 2017.

My guess is that is when they last changed the offset, so the -37s has been in effect since then.

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srean
1 hour ago
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What happens to systems such as Spanner under these circumstances?

Is it a headache or a non-issue

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bri3d
1 hour ago
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It’s a huge problem. The most common approach to address it is called smearing; the duration of each second for a 24 hour period ahead of the “leap” is adjusted. For strict ordering systems this works as each device maintains time sync with the global clock, the duration of a clock cycle is just slightly different. I think this was in the original Spanner paper, actually.

Some rare systems use monotonic oscillator seconds and ignore the earth rotation second, but if you ever have to translate those to real time, you get an accumulating disaster over time and it’s generally regarded as not a good idea.

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criddell
1 hour ago
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I wonder if that's what electricity producers do? If you are selling 50 or 60 Hz service, an extra second here or there must really mess things up.
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lgeorget
42 minutes ago
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A few years ago, a dispute between Kosovo and Serbia caused the entire European grid to drift away from 50.000Hz down to 49.996Hz. Millions of microwave clocks across the continent ended up 6 minutes late: https://hackaday.com/2018/03/09/europe-loses-six-minutes-due....
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jefftk
50 minutes ago
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Clocks used to be able to use the 60Hz cycle to track time, and grid providers would run slightly slow or fast ("time error correction") to get back into sync. A leap second would just be part of this.

I believe in the US this error correction has been discontinued in the East and in Texas, but is still done in the West for some kind of non-clock "inadvertent interchange" reasons I don't understand.

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wincy
2 minutes ago
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Wait is that why my oven and microwave clocks are constantly getting out of sync by multiple minutes every year?
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metalliqaz
1 hour ago
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Leap seconds are not added on a regular schedule like leap days, they depend on physical measurements of Earth. So high reliability systems with comprehensive timekeeping would not be perturbed by these choices, I would think.
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dodoisdodo
28 minutes ago
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The real Time Variance Authority
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voidUpdate
1 hour ago
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I enjoy how Chrome asks me if I want to auto translate from German to English. Where did it get German from? It's French!
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bhaney
1 hour ago
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Probably from the "Content-Language: de" header
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rpozarickij
39 minutes ago
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According to Wikipedia [0] the headquarters of IERS (International Earth Rotation and Reference Systems Service) is in Frankfurt, Germany (contact information on their website [1] has an address in Frankfurt too). The web server hosting the linked file also contains German text in its error page:

> Dieser URL wird nicht beantwortet. Bitte wenden Sie sich mit Ihrer Anfrage an das Bundesamt fuer Kartographie und Geodaesie.

[0] https://en.wikipedia.org/wiki/International_Earth_Rotation_a...

[1] https://www.iers.org

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raverbashing
1 hour ago
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Ok but that makes even less sense
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simlevesque
1 hour ago
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It's a mix of french and english... so it's german.
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lopis
1 hour ago
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A mix of English and French is just called... English
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fhars
1 hour ago
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tosti
1 hour ago
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Frenglish
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Gander5739
1 hour ago
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Franglais?
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Wingy
1 hour ago
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Does this mean the negative leap second isn't happening anymore?
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linux2647
1 hour ago
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Not anymore forever. We’re just not adding one for this year. We might need one next year, we might not. It all depends on the Earth’s rotation and orbit
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NooneAtAll3
46 minutes ago
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and Earth's rotation was too fast for last several years

we were all waiting for the negative leap second to finally happen - but cowards got too afraid

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tedd4u
50 minutes ago
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There's an opportunity to insert or remove a leap second twice a year. They only decide about 6 months in advance of each opportunity what to do (leap second, skipped second, or do nothing).
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ChrisArchitect
1 hour ago
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Notice they only said leap second.

Meanwhile....

International timekeepers to vote on changing the leap second to a leap hour

https://www.scientificamerican.com/article/international-tim... (https://archive.ph/GnQUj https://news.ycombinator.com/item?id=48842329)

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_joel
1 hour ago
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really, my I just don't have the time to keep up with this.
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icepush
1 hour ago
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We can change that!
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tialaramex
49 minutes ago
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A leap hour wouldn't affect you.

In practice it will never affect anyone because it's a legal fiction, but even if you pretend to believe we would actually introduce this "leap hour" it would be in the distant future long after we're all dead and if there are still humans who have any idea the year 2026 happened they're not sure which of Donald Trump, Taylor Swift, Tony Stark and John McClane were real people.

Edited to add:

This is such a ridiculously long time frame that they might not be sure whether we were worried about climate change, for them that's either a disaster they survived (and maybe most didn't) or it's a weird blip in their historical charts which they struggle to explain. Did our civilisation do something very, very stupid? There is a flammable gas deep underground, did we set fire to it because we were crazy? Why the hell would we have done that? There are signs we deliberately set fire to the coal which is a toxic rock also found underground? That would explain the global climate going nuts. Maybe it was a ritual or something. Ancient people are mad.

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Epa095
12 minutes ago
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Up until now we have added 1 leap second every 2 year (27 leap seconds since 1972). So if it continues like this, in 7200 years it would be 1 whole hour, and in "only" 3602 years it will be closer to the next hour than the previous (so a natural time to add the leap hour).
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