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An Average Earth Day Used To Be Less Than 19 Hours Long (theguardian.com)
Scientists have determined that some 1.4 billion years ago, an Earth day -- that is, a full rotation around its axis -- took 18 hours and 41 minutes, rather than the familiar 24 hours. The Guardian reports: According to fresh calculations, a day on Earth was a full five hours and fifteen minutes shorter a billion or so years ago, well before complex life spread around the planet. Scientists used a combination of astronomical theory and geochemical signatures buried in ancient rocks to show that 1.4bn years ago the Earth turned a full revolution on its axis every 18 hours and 41 minutes. The number means that, on average, the length of the day on Earth has grown by approximately one 74 thousandth of a second per year since Precambrian times, a trend that is expected to continue for millions, if not billions, of years more.
So I just have to wait a few hundred million years for those extra hours each day I have been wanting? Sweet.
-- All that is necessary for the triumph of evil is that good men do nothing. -- Edmund Burke
It has been known for a long time that due to moon's effects on tidal bulges, the Earth's rotation has been slowing as the moon moves further away.
Resist our Sloth Overlords!
Make sure you run counter to the Earth's rotation, so that it speeds up!
-- Tigger warning: This post may contain tiggers! --
I'm pretty sure that the earth isn't going to be spinning anymore once it's been engulfed by the expanding sun. It's not going to be doing anything anything.
File under 'M' for 'Manic ranting'
1.4 bn years of that time, or years from our time?
Slashdot, fix the reply notifications... You won't get away with it...
I mean, do we really need a full 24 hours to act environmentally aware if we don't do it the rest of the year?
"Have you ever thought about just turning off the TV, sitting down with your kids, and hitting them?"
Just what I was thinking. Seems to me I read that by 4 billion years from now the sun will be a red giant the size of the earth's orbit.
Musk and NASA better speed up getting the human race to Mars as well as other inhabitable planets.
In a time of universal deceit, telling the truth is a revolutionary act. George Orwell
Just what I was thinking. Seems to me I read that by 4 billion years from now the sun will be a red giant the size of the earth's orbit.
Fantastic. That's approximately when I expect to be able to finally retire.
"That's the way to do it" - Punch
I think my employer has figured out how to stretch a 24 hr day into 30 hrs on a regular basis
Actually the latest thinking is the the orbit of Earth might expand enough to avoid the incineration Mercury and Venus get. Then the only question is how long it takes the Earth's orbit to decay into the "black dwarf" that the sun will cool into. that timescale is unbelievably huge.
Barring extinction by some event before then, I have little doubt we will be a fully interstellar species before the next turn of the millennium.
File under 'M' for 'Manic ranting'
Yes, but there would have been 469.188 days per year, unless the earth's rotation around the sun has also been slowing in which case there would have been fewer. Regardless, that would suck because employers still only gave 15-20 days off and required 8 hour workdays. Maybe the extra ~104 days were all weekend days?
When the rotation speed was higher
https://xkcd.com/162/
We will be long gone by then... there's no rush.
Barring extinction by some event before then, I have little doubt we will be a fully interstellar species before the next turn of the millennium.
It would be a pretty depressing thing if we weren't interplanetary by 2118. Interstellar? That's a different order of magnitude and impossible to guess when we might even come close to that.
"That's the way to do it" - Punch
I can't remember where I read or heard this, but the moon and Earth's days would eventually be the same length and they'd lock into each other.
So in order to preserve the traditional 24 hour day that is the foundation of our society and culture, we must destroy the Moon.
“Common sense is not so common.” — Voltaire
Doing the math on a slowing of 1/74,000th of a second (per year) and 1.4bn years, comes out to a rotation speed of 18.75 hours per revolution 1.4bn years ago. Amazingly close to the 18 hrs and 41 min claimed in the article. If the extrapolation is this close, why bother with the "astronomical theory, geochemical signatures, and modeling"?...just for confirmation?
you can look that one up, about 50 billion years, and the latest calculations (educated guesses with numbers) are that the earth won't be vaporized by the sun when it becomes a red dwarf but instead Earth's orbit will expand enough to save it
Not only do we have fake news to deal with, but now we have old news to deal with?
I've known for over a decade that the earth's rotation has slowed drastically (see episodes 5). Anyone with any physics background in the last few decades knew this. Hell, even stackexchange would consider this old news.
After reading the article, I get the feeling that the person writing it knows as much about science as an ant knows about baking pizzas.
I was saying interstellar, not merely interplanetary. Obviously we will be interplanetary much sooner.
File under 'M' for 'Manic ranting'
Scientists have determined that some 1.4 billion years ago, an Earth day -- that is, a full rotation around its axis -- took 18 hours and 41 minutes, rather than the familiar 24 hours.
If you're going to go so far as to specify "a full rotation around its axis" - a sidereal day - then you should know that that does not currently take 24 hours. It takes 23 hours and 56 minutes (and 4 seconds).
The article gets it right when it says:
According to fresh calculations, a day on Earth was a full five hours and fifteen minutes shorter
systemd is Roko's Basilisk.
The article (which you can download with Sci-Hub) is not about the length of Earth's day, although it does produce a new and more accurate estimate of it at early epochs on Earth. The paper is really about the Milankovitch Cycle that controls climate on a ~22,000 year time scale which be evident if TFS bothered to include the paper's title Proterozoic Milankovitch cycles and the history of the solar system.
The main purpose of the study was to use geological data to construct the Milankovitch cycle going back more than a billion years.
Starships were meant to fly, Hands up and touch the sky - Nicky Minaj
In Soviet Earth, life slows down the world.
sed -e 's/Chuck Norris/Rajnikant/g' joke > fact
Umm, "before the turn of the millennium" means "before 3000AD", not before 2118....
"I do not agree with what you say, but I will defend to the death your right to say it"
An hour still would have been defined as 1/24th of the day. The hours themselves would have just been shorter when compared to phenomena that were not intrinsically tied to the rotation of the earth. Think of how sundials work and how they influenced the idea of an hour; the shadow on the sundial wouldn't just magically skip over several hours each day.
Damn_registrars has no butt-hole. Damn_registrars has no use for a butt-hole.
p>Umm, "before the turn of the millennium" means "before 3000AD", not before 2118....
No kidding!
"That's the way to do it" - Punch
Is an hour 1/24 of a day, or is it 3599-3601 seconds? Because if it's the latter, it has nothing to do with Earth's rotation.
According to NIST: The second is the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom.
I'm sorry, but your opinion seems to be wrong.
Defined in that way, an hour is not a measure of time: it's a measure of relative motion.
The modern hour has since be redefined as a proper measure of time, relative to some kind of gnomonic nanofizz emanating from caesium-133.
(Somehow caesium-133 must be inherently more "timey" than planet earth.)
Julian Barbour apparently doesn't think that time really exists in deep physics; he seems to believe it's relative motion all the way down.
... and since all of the weight is distributed on the outside of the sphere, it slows rotation down. But if dying early isn't going to make people lose weight, I doubt having fewer days in the time they do have will manage it.
Using the ancient paintings of eclipses and comparing with the predictions using Newton's laws of motions shows some discrepancy. If this is assumed due to shift of moon than conservation of angular momentum implies drifting of moon of 3 cm/yr. This was known for over a century ago. Using this knowledge and doing back of the envelope calculations game me almost same results. So there is nothing new here.
Are our years shortening or lengthening? When the Sun goes to Gas giant, will this be resolved? I gotta put it on my calendar. Pretty sure this is against our policy of delivering Less content for more money every year. This just doesn't make financial sense. We'll have to find our way out of this arrangement. --- and last... does this mean there is cosmic torsional friction.. where the vacuum of space is bleeding off speed??? I got it!! Its that damn Dark matter!
Time for a new Political party in the US (or two!) One is off the rails Other cant pony up a leader.
All that weight moving around on the planet, is slowing it down LOL.
An earlier article talked about slowing hurricanes the first thing that came to mind was the slowing rotation while not much it can be quite a change for the climate. The bigger the fluctuation of temp between night and day due to heating for a fraction longer and cooling a fraction longer and newtons law of cooling seems to be an exponential relation, this should have a measurable effect on climate after just a century
Your'e all thinking it, I just said it for you
I attended a presentation regarding the rhythmites relation to the length of the day some 18 years ago. Sure took a long time to verify the hypothesis.
The shepherds did so well protecting the flock that the sheep no longer believed that wolves existed.
they don't even know what happened 10.000 years ago
This is young Earth creationism on a whole new level. I'm pretty sure we know what happened in 2008...
Only crack the nuts that crack. You don't put the ones that don't crack in the sack.
An hour still would have been defined as 1/24th of the day.
That was the original definition but this would mean that an hour would be changing on a continuous basis as the Earth's rotation is affected by tidal forces etc. This would make it useless for many things in the modern world e.g. GPS. As a result, now an hour is defined as 3,600 seconds and a second is defined in terms of periods of radiation from a particular transition in a caesium atom.
Panicked for a moment - the first time I thought it said 4 million.
Confucius say, "Find worm in apple - bad. Find half a worm - worse."
True, but I also said interstellar, not merely interplanetary.
File under 'M' for 'Manic ranting'
If a day was shorter a billion years ago, does that mean a year was also shorter or does that mean there were more days in a year?
If the year is shorter then a 100,00 years (1 billion years ago) wouldn't be the same duration as a 100,000 years currently.....correct?
I've always said English was my second language. Had Romeo and Juliet been written in C, I might have understood it.
Perfect! In just about 3000 years we'll have those perfect 24-hour days we've been longing for! Leap years will become obsolete.. and after that .. they'll be negative.. like once in every couple of years, February will be 27 days long.. COOL!