[HN Gopher] Earth sets new record for shortest day
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Earth sets new record for shortest day
Author : swamp40
Score : 56 points
Date : 2022-08-02 19:46 UTC (3 hours ago)
(HTM) web link (www.timeanddate.com)
(TXT) w3m dump (www.timeanddate.com)
| zeeb wrote:
| Well done, everyone!
| h2odragon wrote:
| From the added momentum from various historical figures whirling
| in their graves.
|
| See now if we'd paid a bit more attention to orienting them
| properly (not too late now!) we could use that angular momentum
| to straighten the earth's axis and thereby eliminate the scourge
| of winter! Or at least banish it to the benighted polar lands
| where it belongs.
| alchemist1e9 wrote:
| Speak for yourself. I can't stand the summer. It's the worst.
| cyberpunk wrote:
| wasps, mosquitos, too hot to cycle and no snowboarding? I'll
| pass too ;)
| NeoTar wrote:
| Or move to somewhere in the new world where it is perpetual
| winter and enjoying those things all year round?
| smm11 wrote:
| Or at least orient things so southern areas are lighter, later
| at night, than northern areas, during the summertime.
|
| You know, since the sun is in the southern sky then ...
| dexwiz wrote:
| http://dresdencodak.com/2010/06/03/dark-science-01/
| twawaaay wrote:
| Lack of understanding of the relation between 24 hours and
| rotational period of Earth.
|
| Earth does not take anywhere close to 24 hours to complete a
| rotation, regardless of how you measure it.
|
| Earth rotates in 23h 56m 4s with relation to distant stars.
|
| Earth rotates in 24h +- 30s with relation to Sun. The length of
| day depends on how far Earth is from the Sun, the speed at which
| Earth rotates the Sun changes throughout the orbit. And so every
| day the Sun makes a different distance around Earth (as seen from
| Earth), making the day a little bit longer or shorter.
| kingkawn wrote:
| 23h56m4s doesn't come in at "anywhere close?"
| twawaaay wrote:
| They are talking about 1ms diff from 24h as being a lot. 4
| minutes is hundreds of thousands larger difference.
| dariusj18 wrote:
| No, that's super far off astronomically speaking.
| kingkawn wrote:
| https://en.m.wikipedia.org/wiki/Pedant
| [deleted]
| twawaaay wrote:
| Science is based on measurements and metrology is
| essentially pedantry, so... a compliment? (And I am aware
| this is bad logic.)
| corentin88 wrote:
| > A negative leap second would mean that our clocks skip one
| second, which could potentially create problems for IT systems.
|
| At least biggest cloud providers have already envisioned this
| [1].
|
| > A negative leap second, if one were ever to occur, would be
| smeared by speeding up clocks over the 86,399 SI seconds from
| noon to noon.
|
| [1] https://developers.google.com/time/smear?hl=en
| LeoPanthera wrote:
| Why is a leap smear necessary for skipping forwards? Unlike a
| typical leap second, which goes backwards, a forward jump
| doesn't repeat timestamps. The clock could literally just jump
| forwards a second and it would be fine.
| bpodgursky wrote:
| This breaks down when you think of all the code that assumes
| 60 seconds in a minute:
|
| ONE_HOUR_AGO = 60*60
|
| Apply that to the wrong hour and... oops.
| LeoPanthera wrote:
| Ah, so this is another "Falsehoods programmers believe
| about time" situation.
|
| https://gist.github.com/timvisee/fcda9bbdff88d45cc9061606b4
| b...
| bpodgursky wrote:
| I don't really want to get into what code should or
| shouldn't have been written. When you are designing
| infrastructure to support millions of lines of existing
| code, you figure out what will break the least code, and
| you do it.
| Dylan16807 wrote:
| I wouldn't go as far as "falsehood". Leap seconds aren't
| inherent to timekeeping. It's easier to do without them,
| and a system like that isn't wrong.
| LeoPanthera wrote:
| > Leap seconds aren't inherent to timekeeping.
|
| Leap seconds are inherent to timekeeping based on the
| sun, which all civil time is. Without them, "midday" and
| "midnight" become undefined.
| Dylan16807 wrote:
| Civil time is based on time zones, and it will take
| thousands of years to have a meaningful drift in
| comparison to that. If we avoid the hubris of thinking
| that we know how clocks will be set hundreds of years in
| the future, then the error from lacking leap seconds is
| negligible.
|
| And it's not like allowing .9 seconds of drift is
| objectively correct either.
| fanf2 wrote:
| The main worry about a negative leap second is that we have
| never had one so we don't know what surprising failure modes
| might turn up.
| notatoad wrote:
| envisioned it and actually experienced it are different things
| though.
| quench wrote:
| Surprised by this error from time and date .com the earth does
| not rotate once every 24H of course, that's the time it takes for
| the sun to be back in the same position (mean solar day) the
| earth rotates once every sidereal day 23h 56m 4s (minus the
| 1.55ns)
| NotYourLawyer wrote:
| Yep, this is because the earth spins the same direction as its
| rotation around the sun. So each year, there's a discrepancy of
| one day.
|
| And 24 hours / 365 = about 3.9 minutes of discrepancy per day.
| gmiller123456 wrote:
| I picked up on that too. I generally expect that type of
| simplification in non-technical articles geared toward the
| general public. But this one was specific enough that I think
| it deserved a mention.
| sebzim4500 wrote:
| It's not even the time until the sun returns to the same
| position in the sky, since the earth's orbit is not a circle.
| NDizzle wrote:
| fanf2 wrote:
| The short-term length-of-day chart is very noisy, and has some
| seasonal components as well. The IERS Bulletin A has a table of
| DUT1 values for the next year, plus a formula for longer-term
| projections. (LoD is the rate of change of DUT1.) If you ignore
| the seasonal components, it is a simple linear formula,
| multiplying the Julian day number by a LoD factor. Last time I
| looked this longer-term LoD factor was 320ms short of 24 hours,
| which suggests the next leap second will be in about 5 years time
| (2027) and will be a negative leap second.
|
| There was a short period towards the start of this year when it
| looked like the LoD was increasing, but that was only temporary.
| The decrease in LoD has been fairly consistent (apart from the
| occasional pause like earlier this year) for a few years,
| starting when the LoD was more like 1ms slower than 24h, so it
| was a while before the wider time-keeping community realised
| something weird is happening.
|
| I am collecting various links and notes and bits of code on this
| and related topics at https://dotat.at/writing/time.html
| mkl wrote:
| Geologically and astronomically speaking, this is actually one of
| Earth's _longest_ ever days. Earth 's rotation has been slowing
| down for billions of years as it loses angular momentum to the
| moon. See e.g. https://www.scientificamerican.com/article/earth-
| rotation-su..., http://www.iea.usp.br/en/news/when-a-day-lasted-
| only-four-ho....
| xwdv wrote:
| Could speeding the earth by some significant amount improve
| cooling performance? Sun rays spend less time hitting one area?
| thehappypm wrote:
| This is an interesting question. The emission of radiation is
| proportional to the absolute temperature to the fourth power.
| So, the hotter something gets the faster it radiates energy
| out. Its nonlinear so theres definitely some winning strategy.
|
| Energy in is constant, but energy out could vary. I think the
| way to maximize the energy leaving the planet is to not rotate
| at all. The energy input would be concentrated and you would
| have one side very hot -- and the hot side would dump the most
| energy back into space.
| srcreigh wrote:
| This reminds me of a video which answers the question "Is it
| Better to Walk or Run in the Rain?"
|
| https://www.youtube.com/watch?v=3MqYE2UuN24
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