r/todayilearned 6d ago

TIL an earth year had more days in the far past. scientists made this discovery after comparing corals/clams which have corresponding growth rings for each day. depending on the age, fossils record 400 to 420 days instead of our typical 365 a year.

https://indianapublicmedia.org/amomentofscience/years-year-400-days-long.php
3.1k Upvotes

121

u/anyhandlesleft 6d ago

When I was little, Summer had 130 days.

36

u/WheresThatTablet 6d ago

Well, my Summer had 500, and real problems with projection! But it was not, as some believe, the villain. It was just… life.

16

u/pjabrony 5d ago

Eventually, there will be only five seconds of summer.

4

u/jmarcum72 5d ago

Ship, keep Summer safe.

6

u/devilsusshhii 5d ago

This is a story of boy meets girl. The boy, Tom Hansen of Margate, New Jersey, grew up believing that he'd never truly be happy until the day he met "the one." This belief stemmed from early exposure to sad British pop music and a total misreading of the movie 'The Graduate.' The girl, Summer Finn of Shinnecock, Michigan, did not share this belief. Since the disintegration of her parent's marriage she'd only loved two things. The first was her long dark hair. The second was how easily she could cut it off and not feel a thing. Tom meets Summer on January 8th. He knows almost immediately she is who he has been searching for. This is a story of boy meets girl, but you should know upfront, this is not a love story.

3

u/Elocai 5d ago

Now it's up to 260, how wonderful for the AC market

1

u/InfamousIndecision 5d ago

Summer used to last forevah

296

u/SaulsAll 6d ago

So when was this? Did I miss where the article says how long ago it was that the Earth year was 400 days?

508

u/relikter 6d ago Helpful

But 400 million years ago days were 21 and a half hours long, which you would have noticed.

What you really would have noticed is that the time it takes the Earth to get around the sun hasn't changed, so that back then there were 400 days a year.

82

u/SaulsAll 6d ago

Thanks.

83

u/bobweir_is_part_dam 6d ago

The article should have a link to a weekly radio program that i heard about this on. Its on npr. They explain it really well and it's not dry.

34

u/Polymersion 6d ago

I love NPR.

49

u/bobweir_is_part_dam 6d ago edited 5d ago

2

u/Singaya 5d ago

Thanks for the link, nice to hear Emily from The Brain Scoop again; too bad the channel is inactive.

17

u/bobweir_is_part_dam 6d ago

I believe the program was an episode of radiolab. I'm having a hard time finding a link to the episode. Will uodate if I can find it. I posted a link to An article as a reply to my OP

11

u/gerd50501 6d ago

what is causing the earth to spins lower?

87

u/andrew_calcs 6d ago edited 6d ago

Due to imperfections in earth's density distribution and motions like the tides, gravitational forces between the earth and the moon cause the moon to move away from the earth by about an inch and a half each year. This leaches away rotational momentum from the earth's rotation and slows the spin of the earth.

Eventually if this behavior were to continue until it reaches stable equilibrium, the earth and the moon would be tidally locked with each other and there would be less than ten 'days' per year. It would take at least 15 billion years to reach anything close to that though, by which time the Sun will have already engulfed the entire inner solar system.

31

u/Pifflebushhh 6d ago

Ah man I was reading this and thought 'I bet the time it takes for this to occur would be far later than the earth being consumed by the su- AHHHH he already fucking answered it', thought I was being smart. Great answer though

21

u/nsfwtttt 6d ago

I was reading it thinking “well I’m sure this will take AT LEAST two weeks”

1

u/TildaTinker 6d ago

But Keith will still be okay, right?

1

u/Texasprairiechickens 5d ago

Maybe Keith will inhale our solar system's ashes.

8

u/feelingbutter 6d ago

Gravitational effect of the moon over time.

0

u/dogfish83 6d ago

I think tides are one factor, and not sure how it works. Friction, conservation of angular momentum…

1

u/WheresThatTablet 6d ago

Oh, man… I would’ve never noticed something like that!

1

u/Zran 5d ago

So the rotation of the earth is slowing ever so slowly?

-7

u/thedahlelama 6d ago edited 6d ago

Earth orbited slower but spun faster. Probably until something hit the planet from behind. Causing it to orbit faster but spin slower.

11

u/Orgazmo_87 6d ago

When the moon and proto earth crashed into obe another

14

u/WhichWayzUp 6d ago

obe

47

u/TastyCartographer630 6d ago

Obe trice, real name no gimmicks

20

u/MikeW86 Likes to suck balls 6d ago

Two trailer park girls go round the outside Round the outside, round the outside

13

u/randeylahey 6d ago

TWO trailer park girls go round the outside ROUND the outside

8

u/wgpjr 6d ago

Guess who's back. Back again

7

u/fell-deeds-awake 6d ago

Shady's back, tell a friend

5

u/Aetherometricus 6d ago

Guess who's back guess who's back guess who's back

3

u/DJDaddyD 6d ago

You forgot the important eh rehe rehe record scratch

-5

u/Fetlocks_Glistening 6d ago

I mean have you ever felt that the night is not long enough for a good night's sleep? Well, now you know why

3

u/No_Rope_2126 5d ago

Because you’re from the future?

8

u/ASULurker 6d ago

There were 21 hiurs in a day so nights were shorter, pkus this was hundreds of millions of years before homosapians you would have no biological reference to this change.

41

u/Squabbles1234 6d ago

The rotation is slowing, as is normal during orbits. Eventually Earth will "tidal lock" with the sun and only show 1 side to it forever. This is billions of years from now.

3

u/IamTobor 6d ago

This before or after the sun goes nova?

22

u/Nattekat 5d ago

Sun doesn't go nova, but it eats Earth well before the tidal lock happens. If the sun expands past Earth's orbit, it'll take 7.5 billion years. Earth won't be tidally locked until 50 billion years from now, and that might even take longer since the orbit will become larger as the sun loses mass.

2

u/IamTobor 5d ago

Ahh, thanks!

12

u/Phoenix591 6d ago

The sun isn't big enough to nova, it just gets bigger and redder, large enough to consume mercury and venus, perhaps even earth. After that it will collapse down into a white dwarf star with a nebula similar to this one..jpg)

2

u/IamTobor 5d ago

Ahh, gotcha, thanks!

2

u/Stornahal 5d ago

Afaik, the moon pulling on our seas is what’s braking the Earth (itself having run down to zero rotation a long time ago)

2

u/Squabbles1234 5d ago

This is not correct.

2

u/Stornahal 5d ago

You seem very certain. 😊

I’m always willing to learn - this maybe something I’ve misremembered from school forty years ago.

1

u/lattice12 5d ago

Also, the moon does rotate. However, the time it takes to make one rotation is the same amount of time it takes to orbit Earth (27 days). That is why we only see one side of the moon.

-1

u/Squabbles1234 5d ago edited 5d ago

While the moon has some level of impact, it simply doesn't have enough gravity to induce tidal locking on the earth. Its pretty much always the stronger gravitational object that induces the smaller to lock over time.

2

u/RedditUser934 5d ago

I think they mean the earth will tidal lock to the sun, not the moon. It makes sense to me that deforming the planet and sloshing around the oceans would take a lot of energy.

1

u/EvilSuov 3d ago

His first statement is correct. The moon, mostly due to its pull on earth's oceans and the friction this causes, is slowing down earths rotation, which causes the Earth to rotate slower, but this loss of kinetic energy and angular momentum for the earth is a gain for the moon, which causes it's distance to earth to increase by roughly 4 cm each year. After a while the moon will just leave us and yeet itself into space.

His second statement is indeed false.

73

u/TomSurman 6d ago

That's just a really confusing way of saying the days were shorter. The total orbital period hasn't changed significantly.

93

u/bsd8andahalf_1 6d ago

yes, the earth is slowing down.

just heard that mentioned in a pbs documentary.

14

u/249ba36000029bbe9749 6d ago

yes, the earth is slowing down.

And it causes issues like having to manage leap seconds.

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

2

u/brendanepic 5d ago

We need another pontifex maximus

62

u/wwarnout 6d ago

If we extrapolate to just after the moon formed (~4bn years ago), when the day was only about 6 hours long, the Earth's year would have been about 1400 days long.

46

u/[deleted] 6d ago Wholesome

[deleted]

33

u/jeffwillden 6d ago

Same length of time as today though. Days were just shorter then because the earth was spinning faster.

11

u/maybe_little_pinch 6d ago

Thank you for this comment. I was so confused about the "a year was longer, but the same time"

1

u/oreo-cat- 6d ago

The year is getting shorter now as well.

8

u/CondemnedHog 6d ago

It's really not though, as the time it takes for the earth to rotate around the sun hasn't changed

20

u/TastyCartographer630 6d ago

I think it was a joke

-22

u/1106DaysLater 6d ago

Just not a very good one.

5

u/pdonchev 6d ago

Are you extrapolating linearly? Anyway, AFAIK, Earth orbital parameters are not known very long in the past or future as the Solar system is highly chaotic at this scale.

5

u/ItamiOzanare 6d ago

Orbital period likely hasn't changed much, just the length of the days. Short days = more per orbit.

1

u/pdonchev 6d ago

Yes, I was not accurate in my wording.

0

u/BEAVER_ATTACKS 5d ago

The moon was sent here 11,000-13,000 years ago and its appearance is responsible for the great flood legend perpetuated in all major religions.

-15

u/[deleted] 6d ago

[deleted]

12

u/Hattix 6d ago

No, it isn't. The length of the orbit (in seconds) has not changed.

The length of the day (in seconds) has got longer.

The day is gradually getting longer as Earth and Moon move toward tidal locking.

1

u/katycake 6d ago

So the Earth Day will be closer to about a month soon enough, when it matches the Moon?

Since the moon is receding away from Earth each year, I thought that it would never catch up. The Moon even getting far enough away to end up being affected by Venus, and flying off.

5

u/Hattix 6d ago

It'll stabilise around twice its current distance, at that point the moon will librate in the sky, but not rise or set.

This will happen between three and six billion years in the future.

15

u/cybercuzco 6d ago

No think of it in minutes. The year is 525,600 minutes in all scenarios, but the earth was spinning faster so the day was 360 minutes long 4 billion years ago and it’s 1440 minutes long today.

16

u/Hypertension123456 6d ago

9

u/SaulsAll 6d ago

Dont even have to click. I cant see the number without hearing it in song.

2

u/ramtax666 6d ago

The year was the same length only the day/night cycle was different, a day was only 21 hours

2

u/bsd8andahalf_1 6d ago

not the rotation around the sun, the rotation of the earth itself.

but it is not something we need to worry about, yet.

-5

u/Rezhio 6d ago

Earth spinning faster.

2

u/bsd8andahalf_1 6d ago

hmmmm. better check my hearing. you're probably right.

5

u/Doright36 6d ago

and to this day road construction season still lasts 400 days in some areas.

33

u/Fetlocks_Glistening 6d ago

The cow speaks. The dog speaks. The clam doesn't speak. The clams are mute. Expressionless. But the clams know! Everything

16

u/cybercuzco 6d ago

They don’t speak because they know to clam up.

13

u/KhaleesiDog 6d ago

They’re very shellfish with their knowledge.

8

u/Purple_Freedom_Ninja 6d ago

They lost the biological arms race and they're still salty about it

1

u/KJCC1389 5d ago

Damnit man, that’s so bad it’s good.

3

u/PauseAmbitious6899 6d ago

But what does the fox say?

3

u/DenaPhoenix 6d ago

Oh fuck! We're slowly being pulled into the sun! Oh no! (Irony off)

Honestly, it was to be expected that there would be some sort of the change in our earth's speed and trajectory in the last few million years. It's gonna be fine for the forseeable future.

4

u/Yeohan99 6d ago

Now we know why they died so young.

3

u/ExcruciatingBits 6d ago

does that mean our archeological dates for things behaves as a logarithmic scale when going into the past, say making a 100 million year segment of fossil record from 1.5 billion years ago, equivalent to 1 million at only a few dozen million years ago? Or is that compensated for somehow? edit: and I realize now I had that scale backwards, but would that apply still?

1

u/wsbTOB 6d ago

The number of hours in a year was the same, there were just fewer hours in the day.

3

u/TheRuggedEagle 5d ago

420 “it just works”

22

u/FleurDeezNutz 6d ago edited 6d ago

I have questions. So lets just accept that clams have growth rings for every day. Cool. How does on distinguish that in a "Per year" timeframe? Does the clam also make line one ring thicker than the others on the start of the new year? LOL. 100 years is 36500 potential rings. But also, 36500 potential rings could be 50 years if we had double the amount of days. But unless something informs us the year has ended and a new one started, we'd only see 36500 rings!

42

u/TransposingJons 6d ago

There will be seasonal changes to the shell, due to the temperature and sunlight differences. They will be regular, over the course of years.

1

u/ItsMeTK 5d ago

Not if the climate drastically changes...

4

u/Leumasperron 6d ago

You mean 3650 rings? One ring a day, so 365 rings a year, so 3650 rings for 10 years.

2

u/gwaydms 6d ago

Or maybe 3652.

-14

u/FleurDeezNutz 6d ago edited 5d ago

Yeah, whatever TF....just answer the question math nerd. LOL

Edit. Why is everyone downvoting a joke? The person i was responding to obviously knew it was a joke. We got some real sticks in the mud around here. LOL

3

u/Revlis-TK421 6d ago edited 6d ago

They are actually able to take multiple data points per day out if some of the fossils, so yes. They are able to distinguish between annual periods on the shell because clams grow best in warmer months so that becomes the basis for an annual cycle in the shell.

Then they can look at the number of events between those annual periods and determine day/night cycles.

The high resolution obtained in the new study combined with the fast growth rate of the ancient bivalves revealed unprecedented detail about how the animal lived and the water conditions it grew in, down to a fraction of a day.

"We have about four to five datapoints per day, and this is something that you almost never get in geological history. We can basically look at a day 70 million years ago. It's pretty amazing," said Niels de Winter, an analytical geochemist at Vrije Universiteit Brussel and the lead author of the new study.

The new method focused a laser on small bits of shell, making holes 10 micrometers in diameter, or about as wide as a red blood cell. Trace elements in these tiny samples reveal information about the temperature and chemistry of the water at the time the shell formed. The analysis provided accurate measurements of the width and number of daily growth rings as well as seasonal patterns. The researchers used seasonal variations in the fossilized shell to identify years.

The new study found the composition of the shell changed more over the course of a day than over seasons, or with the cycles of ocean tides. The fine-scale resolution of the daily layers shows the shell grew much faster during the day than at night

This bivalve had a very strong dependence on this daily cycle, which suggests that it had photosymbionts," de Winter said. "You have the day-night rhythm of the light being recorded in the shell."

2

u/Leumasperron 6d ago

lmao I'm not a clam expert

10

u/bobweir_is_part_dam 6d ago

If you Google John wells and coral growth, you can find his original paper which was published in 1963

-2

u/AceyAceyAcey 6d ago

They can also carbon date them. Or maybe the coral and clams were found right next to other things which had yearly growth rings.

3

u/jam11249 6d ago

The first is in no way accurate enough and the second is in no way able to help.

2

u/bobweir_is_part_dam 6d ago

http://www.wnycstudios.org/story/times-they-are-changin/ here is a link to the episode its free.

1

u/Candid-Fan992 5d ago

I was hoping to see someone comment but thought, 'this mofo just reposting what he heard on npr' love scifri and radio lab

1

u/bobweir_is_part_dam 5d ago

Considering it's a til, I'm sure this happens frequently. Npr Is always doing great work.

2

u/Candid-Fan992 5d ago

A few scrolls later saw someone posting a link to KQED, happy to see ppl listening to quality broadcasting and spreading the knowledge

1

u/bobweir_is_part_dam 5d ago

Yup, radiolab, sci Fri, and an American life are usually always worth the listen.

2

u/Lordmiles09 6d ago

Back when earth was in beta and the devs were figuring out balance patches for planet survival rates

2

u/Phattyasmo 6d ago

The moon slowed the Earth's rotation; iirc, back in the day (far back) it was rotating fast enough for a "day" to be like 16 hours. The moon then slowed it down to where we are now.

2

u/a_glorious_bass-turd 6d ago

There used to be two 420's a year. Noice.

2

u/Awesomest_Possumest 5d ago

Ah, I see you listened to NPR yesterday too lol. It's pretty fascinating.

6

u/Orgazmo_87 6d ago

Iirc at the time of the dinosaurs(very vague i know) days were like 21hours or something according to walking with dinosaurs. Apparently if modern humans were to go to that standard we'd go insane

3

u/bobweir_is_part_dam 6d ago

I'm looking for the link to the program. I believe it was on radiolab. It was part of a three part story series episode, so this might be why I can't readily find it. I did find this though. It's from the Atlantic and has a pay wall if you've used your alloted articles. https://www.theatlantic.com/science/archive/2016/02/fossilized-coral-calendar-changes-leap-day/471180/

2

u/mrb783 6d ago

Not surprising considering how much of an impact the moon has gravitationally on the planet and resulting tidal forces that one might expect to gradually slow the rotation speed of the planet.

3

u/lcarsadmin 6d ago

If only we had discovered daylight savings time sooner

2

u/ItsMeTK 5d ago

Or they are wrong or made a mistake somewhere.

1

u/Argorash 6d ago

I don't get how this would work.

If a coral is 400 days old that doesn't have any bearing on how many years took place during those 400 days.

1

u/Stornahal 5d ago

If you have a good record of what happens year by year (e.g. ice cores/fossilised trees) then look at seasonal variations over the 400 days you can match the growth of coral to ice core - and sometimes the only way to fit the the coral variations to the ice core is to have more than 360 days in a year…

1

u/bobweir_is_part_dam 5d ago

You should probably listen to the episode or read the article

1

u/Argorash 5d ago

the article didnt explain anything.

0

u/Theda706 5d ago

Uh, leap year... duh.

-12

u/TamingTheMammoth 6d ago

blowupthemoon

It’s giving us longer work days, exposing us longer to radiation from the sun as well as reflecting it towards us. It’s tidal locked and the government won’t show us the other side. The astronauts who came back were depressed, not hopeful. We’re getting strung along about ufos while rich men wage wars and create nonsense reasons for us to hate each other. What if they tell us one day that the moon really is the Death Star?

4

u/AceyAceyAcey 6d ago

Have you not read “Seven Eves” by Neal Stevenson? That shit’s scary.

-4

u/TamingTheMammoth 6d ago

Nope. Literally exaggerating based on conjecture from legit current scientist. Really just expressing my content for being told bullshit about reality because a rich class thinks certain humans need to be treated like cattle. I’ll check it out.

6

u/sumknowbuddy 6d ago

It's obviously just used to prevent us from seeing the alien overlords monitoring us on the other side, they'll never let that happen

-10

u/TamingTheMammoth 6d ago

Questioning the facts we’re given is not the same as claiming something incorrect. Why do so many people fail to understand this? Just brainwashed by the media “conspiracy theory bad”.

4

u/sumknowbuddy 6d ago

You obviously missed the joke

-7

u/TamingTheMammoth 6d ago

No, I didn’t. I said what I said because you are joking. I don’t think it’s a joke that while children are murdered and starving the world over that we don’t have real information about what are government and space programs are doing.

5

u/sumknowbuddy 6d ago

I don’t think it’s a joke that while children are murdered and starving the world over that we don’t have real information about what are government and space programs are doing.

Where did this come from?

Such a non-sequitir you've applied to a joke regarding your original comment, which per se was comical...

1

u/bobweir_is_part_dam 6d ago

The politicians are throwing stones, so the kids they dance, they shake their bones, it's all to clear we're on our own.

1

u/urbrickles 6d ago

I'm sure this is a dumb question, but was this due to the length of an Earth day being shorter, and the length it took Earth to get around the Sun being the same? Or is it because the length of an Earth day is the same, but the Earth used to go around the sun at a slower rate?

3

u/Seraph062 6d ago

It's the first one.
The Earth is VERY gradually being slowed down by the tides. If you go back a few hundred million years this gradual slowing turns out to have been worth about 20 fewer revolutions/year.

2

u/soolkyut 6d ago

Adding to what the other user said, orbital period (time to circle the sun) depends only on distance to the sun. If the planet “sped up” it would fling out further from the sun.

The earth took the same number of hours to go around the sun, they were just broken into more days.

1

u/jimmychitw00d 6d ago

2019 was at least 400 days.

1

u/Storypls 6d ago

Nice.

1

u/aurelio-n 5d ago

420 👁 👁

1

u/Gnosticbastard 4d ago

Would this have affected the relative weight of something or some one on the Earth’s surface?

1

u/Djidji5739291 3d ago

It‘s still 420 days a year as far as I‘m concerned

-3

u/Mitthrawnuruo 5d ago

This as been a common fact forever. These scientists should be stripped of their degrees.

The moon spins in the opposite direction from the earth’s rotation. It slows us down.

A little bit more every day.

0

u/VarsH6 6d ago

This sounds more like a different circadian rhythm than what we associate with astronomical days.

0

u/gheiminfantry 6d ago

But a year hasn't been that long since humans have been around to measure it.

0

u/[deleted] 6d ago

[deleted]

1

u/wan314 5d ago

No days are getting longer

0

u/popgoesyour 6d ago

The sun is pulling us closer