# Earth's rotation sped up in 2020, we may need a "negative leap second"

Originally published at: https://boingboing.net/2021/01/10/earths-rotation-sped-up-in-2020-we-may-need-a-negative-leap-second.html

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I knew something was off!
Good to know what it is.

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I recorded the leap second in 2016. It had an extra second to accommodate the slower Earth. So this would mean that next year-end we’d lose a second instead of gaining one, going from 23:59:58 to 00:00:00 UTC.
It makes sense to abandon the leap second, since the solstice isn’t on the new year anyways, so tracking them is a waste of effort.

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Also, there’s this guy Tom Van Baak who runs Leapsecond.com. He’s an interesting fellow. He’s done experiments wherein he shows that time runs a bit slower at higher elevations due to relativity, using two arrays of cesium clocks, one in his minivan.

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Welp, she’s finally trying to throw us off.

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Leap seconds are about keeping the day/night cycle fixed not the solstice. Without leap seconds you would drift a full time zone in a mere 5000 years…

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Worse - it went from 11:58 to 12:00, but now that missing second has gone rogue, popping up continuously in 2021.

Though almost immediately you end up requiring a completely different “astronomical time,” that slowly diverges from “standard time.”

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They will remove time

GIVE US BACK OUR ELEVEN DAYS!!!1!!!11!

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Without leap seconds we need a leap hour in about 600 years. In 5000 years the difference accumulates to a full day. See the table https://www.ucolick.org/~sla/leapsecs/dutc.html

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I always found it slightly suspicious that leap days work as well as they do (i.e. that the length of a year is so close to being an integer number of quarter-rotations), and sometimes wonder about the odds.

Not that I’m assuming a conspiracy by the hollow-Earth dwellers. I just sort of wonder if there’s some physical harmonic relationship between day length and orbital period. That obviously does happen with tide-locked bodies.

ETA I just looked it up and it’s actually right near the top of Wikipedia’s tidal locking page – Mercury has exactly three days in two years (i.e. a leap year every other year).

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The rotation of the crust of the earth has accelerated so that the mean solar second very nearly matches the SI second of the cesium hyperfine transition. It is extraordinarily unlikely that the acceleration will continue enough to require a negative leap second. Eventually the tidal dissipation from the moon and sun will overcome the temporary angular momentum redistribution inside the earth.

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It’s not. That is why we use the Gregorian rather than the Julian calendar, and 1900 was NOT a leapyear.

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ok,who pulled their arms in tight?

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I love that meme format.

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Well, “close” is subjective, but only needing to correct it in three out of every 400 years strikes me as close. Although I have never wondered hard enough to actually do the math.

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Until 1972 standard time was astronomical time. Now standard time is atomic time, but standard days are still astronomical days.

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So, literally the entire planet just wanted 2020 to be over faster…

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faster, isn’t it

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There is probably resonance in there somewhere. Perhaps between mass concentrations in the Earth’s crust and our orbital eccentricity with the sun. Its a bit like how Mercury was once thought to have a 1:1 relationship between rotation and orbit but it turned out to be 58/87 or 0.6 recurring.

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