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The Times They Are a-Changin'

Monday, December 30, 2013 - 05:30 PM

coral moon by WNYC's Sahar Baharloo

At the start of this new year we crack open some fossils, peer back into ancient seas, and look up at lunar skies to find that a year is not quite as fixed as we thought it was.


With the help of paleontologist Neil Shubin, reporter Emily Graslie and the Field Museum's Paul Mayer we discover that our world is full of ancient coral calendars. Each one of these sea skeletons reveals that once upon a very-long-time-ago, years were shorter by over forty days. And astrophysicist Chis Impey helps us comprehend how the change is all to be blamed on a celestial slow dance with the moon. 

Plus, Robert indulges his curiosity about stopping time and counteracting the spinning of the spheres by taking astrophysicist Neil deGrasse Tyson on a (theoretical) trip to Venus with a rooster and sprinter Usain Bolt.



Emily Graslie, Chris Impey, Paul Mayer, Neil Shubin and Neil deGrasse Tyson


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Comments [40]

Gerald from Oakland

Wait this doesn't add up. According to this episode, Coral fossils indicate that at one point in Earth's history, the were 450 days in a year. Supposedly this due to there being no moon at the time. The problem is that the moon is billions of years old while coral only goes back millions of years. What am I missing??

Jan. 21 2018 03:11 PM
Alyssa Johnson

Can you explain how we got an extra second on Dec 31, 2016

Jan. 17 2017 03:15 PM
Matt from Chattanooga, TN

As someone pointed out above, roosters crow all day long.

Anyway, I live in Hamilton County, Tennessee. We have two counties that form our western border (Marion and Sequatchie) that one reaches by crossing over the eastern side of the Cumberland Plateau (the Plateau, this far south, has been split by a rift valley). Crossing over the boundaries into these counties puts you into the Central Time Zone. In Hamilton, we live in the Eastern. So, by moving west by one county, you "gain" an hour.

In the course of planning a dove hunting trip, and figuring out when we'd need to leave in order to be at the site by daylight, one of the party said something along the lines of, "sunrise is at 6:30" (clearly he'd done his homework) "if we leave at 6:30, and it takes us an hour to get there, with the hour we gain, we'll be there at sunrise."

Perfectly logical, until I asked him if he thought we could watch the sunrise, drive for an hour over the mountain and see the sunrise again.

I've always wanted a good forum to tell this story; commenting on a year-old podcast is probably not the best way to reach a huge audience, but I couldn't help but thinking of it during Robert's questions about Venus.

Aug. 05 2015 04:40 PM
Loreli E. Bond from Florida

I think that this podcast greatly sparked an interest in nature. I was so surprised and even a bit quizzical when they talked about the shell ridges being 365. That is a bit unheard of to me, and I would like to see that myself! I know that those things do happens and parallel lines are drawn, but that is almost bizarre to me. I didn't realize the moon's undertaking in how much it affects the length of our days. The fact that each element between the sun, moon and Earth work perfectly together to sustain life still astonishes me. Overall I thought this to be a very interesting podcast and well worth the time to listen.

Feb. 03 2015 01:24 AM
Elizabeth E. Moore from Florida

This podcast is very interesting. I think its cool how they can find shells and other fossils and see how they relate with years on Earth. I was suprised when they found the shells and were counting the lines and it turned out to be around 365! Archaeology and studying fossils is so fascinating in my opinion. I'm glad I chose this podcast to listen to because it has made me more interested in this subject.

Jan. 13 2015 07:32 AM
Agatha B. Silverstein from Florida

After watching this video I was surprised to learn the moon determines how long our days are and how many we have in a year. The earth slowly pulls on the moon and the moon slowly pulls on us causeing our years to shorten to 365 days from 400 days, and lengthening our days from six hours to twenty-four hours a day. Even crazier is scientists have determined this from comparing the rings on the shell of a modern day coral shell to a prehistoric coral shell. I wonder if eventually our days will shorten and years lengthen over millions of years as the moon drifts further away from the earth?

Oct. 20 2014 11:13 PM

Terry (Miami) picked up the fact of your summary above contradicting what was said in the show. In other words, the years were not shorter (by number of days) but rather longer. However, as stated by Neil Shubin, it's thought that the earth's transit around the sun was the same, but it was spinning faster, thereby shortening the length of a day on earth, and increasing the number of days per year, compared to today. I think I heard 415 days as the former length of the year at one point.

Sep. 20 2014 01:33 PM
Sean from La ca

The more obvious case is the earth is growing from smaller to larger. Changing the rotation rate

Aug. 01 2014 03:25 AM
Kellista from Colorado

I agree with Derek that our Calendar is antiquated. But I think it should be more in harmony with the Sun cycle. It should only go around once in a day. This would reveal the pattern of the Sun rise and Sun sets on the Solstice and Equinoxes. This would allow humanity to align with and utilize Solar Energy as in

Jul. 15 2014 11:08 AM
Benson from Tampa, FL

Love the show! Counting the lines in coral to show years got me thinking. I understand how each line could depict a day/night cycle but the bigger grey lines which show higher growth rates over the course of a summer does not seem to me to depend on a full orbit around the sun or necessarily the length of a day. Couldn't is also be a change in the speed that the earth's axis of rotation "wobbles" over time? The show didn't address the math regarding the length of days changing to show whether that alone would amount to more days in a season.

Jun. 05 2014 01:28 PM

Being able to identify how old fossils are based on rings and bands are amazing. These fossils provide many facts as to what the earth has been through and the amount of days. It is also weird to think that there used to be more days in a year then we currently have. It makes sense that the moon slowed us down, causing shorter years.

Apr. 25 2014 08:28 PM

It is really amazing to discover from age-old fossils how our earth was billions of years ago. It makes much sense that the earth would spin faster as it was younger because it was much smaller; our days were longer. But when the moon was (supposedly) chipped off of the young earth, as we grew the moon only slowed us down which in turn made what we perceive as shorter days. And with the earth getting larger as it grows older, the more weight along with the moon's drag may, in the billions of years to come, make our days seem much shorter than they are at present.

Apr. 10 2014 08:43 PM

It's very interesting how something we consider so permanent as the length of a day or of a year has been changing for billions of years and will continue to do so. If the moon is slowly getting farther away, could it possibly become so far away from Earth it falls out of orbit (in billions of years)?

Apr. 07 2014 08:54 PM
Cameron from Nashville

I have no idea how you all discovered my former a capella group, Groove Society for this feature! We recorded
that album in 2001 ( I was 21 at the time!) back before a capella was cool. My husband, who was also in the group for a time, was listening to this episode on a run. He stopped dead in his tracks when he heard us on RadioLab, how cool?!

Mar. 16 2014 02:05 AM
Jim from Ohio

Enjoyed this show recently on podcast, but am struck that no one has criticized the implication that Bolt or anyone else could quickly turn morning into noon or vice versatile. Venus rotates slowly, but it's not a tiny planet. You could theoretically easily move to keep the sun overhead but you could NOT easily change morning into afternoon. A 1/2 "day" time change requires either a very long wait in Earth time or a very long trip around nearly half the planet's diameter at the equator.

Mar. 12 2014 08:05 AM
KJMiller from Minnesota

What a fantastic show! Fascinating, informative and the banter with Neil deGrass Tyson will be in the history records. A treasure.

Mar. 05 2014 11:30 AM
Mr. Shiitake from

Not sure if you were being funny, but I think they've proven roosters don't crow based on the sun... ...btw...another great show!

Feb. 17 2014 11:16 PM

Dr. Impey said that during the time that the coral was recording 400 day years, the Earth was a molten ooze. That would be about 3 billion years ago and from other sources coral is only about 2 billion years old - at least in the fossil record. Which is it?

Feb. 10 2014 03:18 AM
Nick from Atlanta

The Earth is losing energy to the moon. But, if the moon is moving away from the Earth an inch per year, the force is increasintly becoming less and therefore the deacceleration of Earth's rotations are moving towards a constant? Or, once the gravitational pull from the moon is non-existant, will the roational speed of Earth begin to increase?

Feb. 03 2014 09:20 AM
Terry from Miami

Having listened to the podcast, shouldn't the text say that the year was longer by about 80 days (about 450 per loop around the sun) rather than shorter by 40?

Jan. 24 2014 11:28 AM
Sophia from Australia

The acapella sounds like The Idea of North.

Jan. 20 2014 09:15 AM
Bobbi from Virginia, US

I was sad that you guys didn't mention Emily Graslie's Youtube show, Brain Scoop - It's really interesting and she's funny and engaging.

Jan. 15 2014 08:10 AM

Sometimes when I listen I feel as if I am hearing a children's program. "What do you mean how BIG a year is?" Why can't the narrators just ask direct questions without all the goofy stuff. I like the topics a lot but I wish that Jad and Robert's radio personalities were not so contrived. I realize some people probably like this but I wonder if it bothers anybody else....

Jan. 10 2014 01:52 PM
rebecca from chicago, IL

i know somebody else already asked this but I HAVE to know. Who does that cover version of Moondance at the end of the show. It's fabulous!

Jan. 10 2014 11:52 AM
Reshma Ramani from Japan

Can we see images of the cross sections of the coral reefs?

Jan. 09 2014 11:51 PM

"Time is the wealth of change, but the clock in its parody makes it mere change and no wealth."
Rabindranath Tagore

Jan. 05 2014 11:27 AM
Jim Olsen from Oregon

I loved this program. When discussing the idea of walking around Venus at the equator, he said he wasn't sure of the speed someone would have to walk or jog. The exact speed was available on the internet. You could have paused your interview 2 minutes, found out, and said you or I could do it, not just Mr. Bolt.

Jan. 04 2014 08:22 PM
Jiv from Toronto

Does anyone know the name of the version of "I see the moon and the moon sees me"? The sound quality and arrangement is perfect for a project I'm putting together.

Jan. 04 2014 10:09 AM
Jiv from Toronto

Does anyone know the name of the version of "I see the moon and the moon sees me"? The sound quality and arrangement is perfect for a project I'm putting together.

Jan. 04 2014 10:08 AM
Dave from CA

Did I just see a Gallup Poll were 44% of Americans believe the earth is less than 10,000 years old. Was I the only one....

Jan. 03 2014 06:12 PM

The song is a remix of Moondance by Van Morrison

Jan. 02 2014 02:53 PM

Very interesting story. I would love to hear a story about the sudden change in 701BC when the number of days in one year changed from 360 per year to 365.25. I suspect it was due to a celestial close call... perhaps an elliptcial orbit of Mars passing by (no wonder it is called the Angry Red Planet in historical lore). This last close call was the last time it had that pattern and settled into a more circular orbit. I believe very interesting things happened the times Mars passed by closely to earth in history... corresponding with biblical events. This close passing could also explain why Jonathan Swift using historical documents in his posession was able to predict and write about in Gulliver's Travels the number of moons Mars had over 150 years before they were discovered.
It would make a fascinating story if you guys were to cover it!

Jan. 02 2014 01:57 PM
Chris Lintott from Oxford

The main thing that affects the Earth's orbit around the Sun is the loss of mass as the Sun converts fuel into energy. It's pretty insignificant most of the time, though, as the Earth moves further from the Sun at a rate amounting to something like a meter every century, making the year a millisecond longer every 230 years or so. However, towards the end of the Sun's life things get more exciting, and as the Sun swells into a red giant larger than the present day size of the Earth's orbit our planet may have moved out enough to survive, albeit as not much more than a cinder.

Jan. 02 2014 11:54 AM
Erin from not from Portland

I really dig the song at the end - who is that group? Also - clever picture of the moon made of coral (and here, I thought it was cheese...). Interesting, thought provoking as usual - Happy 2014!!! Thanks!

Jan. 01 2014 06:39 PM
Wutzibu from germany

That was very interesting as usual on Radiolab. I was happy to hear Emily Graslie ont he show, i absolutely adore her Videos even when she has her Arm stuck in a Wolf corpse^^.

Jan. 01 2014 04:47 PM

Fun Facts:

Doing the math, you'd only need to jog 5.5mph (about twice normal adult walking speed) on Venus to keep the sun fixed in the sky. No need to be Usain Bolt.

I recall hearing somewhere the moon's drift from the earth to be about 3cm a year. Thus by the time an average American man of 5ft 9in reaches his 59th birthday the moon has traveled away from the Earth the same distance as the top of his head is from the ground he is standing on. For the average American woman of 5ft 3in it is reached by her 54th birthday.

Dec. 31 2013 06:06 PM
Jim from Grantwood, NJ

Enjoyed "The Times They Are a-Changin'" and enjoy all your programs. A persnickety note...when referring to distances (the moon moving away from Earth) the word is farther not further.

Dec. 31 2013 01:10 PM
Frank Patrick from New Jersey, USA

Two podcasts in my commute playlist this morning...

This one and one from Engines of Our Ingenuity - both on the topic of the slowing down of the Earth's rotation.

Serendipity or just an appropriate sciency topic for New Years?

Dec. 31 2013 01:02 PM

This got me thinking about soooo many things, most seamlessly would be the discussion, or if there could be a discussion about calendars and the design of a new one . . .The Smithsonian had something on it a year ago n"Astrophysicist Richard Conn Henry and economist Steve Hanke argue that we should all adopt Greenwich Mean Time, also known as Universal Time. That would make it the same time everywhere, regardless of the sun’s position in the sky.

Read more:
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Dec. 31 2013 10:08 AM
Jake from Finland

So what about the earth and the sun? The earth is basically a moon of the sun, with similar principals and physics affecting. Are the years getting longer? Are we drifting further?

Dec. 31 2013 04:48 AM

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