Neil deGrasse Tyson Explains Why We Have Leap Days

What’s going on with Leap Year? Neil deGrasse Tyson and comedian Chuck Nice explain why we sometimes have that extra day in February.
Learn about the rotation and orbit of the Earth and how our orbit isn’t exactly 365 days. What is the difference between the Gregorian and Julian Calendar? We take a trip back to 1582 to find out why The Pope took out 10 days of October. Plus, find out why 2000 was such a special leap year.
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Science meets pop culture on StarTalk! Astrophysicist & Hayden Planetarium director Neil deGrasse Tyson, his comic co-hosts, guest celebrities & scientists discuss astronomy, physics, and everything else about life in the universe. Keep Looking Up!
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00:00 - Introduction
00:30 - Why Do We Have a Leap Day?
2:54 - What Do You Do With The Extra Six Hours?
4:13 - The Gregorian Calendar & Problems with The Julian Calendar
9:21 - Why the 2000 Leap Year Was Special
11:36 - The Magic of New Years

[@StarTalk]

Does your birthday fall on a Leap Day?!

[@HandMeDeals]

Yes and my father returns every Leap Day. Im 24 but my father says im technically 6 years old so he takes me to Chuck E Cheese.

[@JordanVargas-bz6ym]

deez nuts

[@jvttvj]

So your birthday celebration is not on your birthday????

[@jvttvj]

😂

[@joeh2236]

Nope, scientists need figure my sign out, lost to many to it

[@Nunya_Bidnez]

We love you Chuck. The Universe would not be the same without you.

[@Eneov]

The universe needs Chuck.

[@SordidusFellatio]

I think it will

[@kidchiko9435]

That is a beautiful sentiment. But in the spirit of Neil, by its very definition the universe would be different with him gone. The butterfly effect alone would require the universe to be slightly different.

[@danceman3000]

Chuck is so important lol

[@jamesstevens9394]

Well. that MIGHT depend on which universe we were in........hmmmmm......

[@kevinflick61]

With Chuck's spot-on comedic touch & Neil's and incredible understanding of how astrophysics, you guys have the most entertaining and informative science show on KZbin.

[@StarTalk]

That's very kind, thank you!

[@anthonygordon9483]

Neil is a comedian himself . Chuck just compliments him.

[@christophermejia5998]

I’m happy I’ve found this channel 🙌🏾

[@user-kw4iu8ge2w]

Love them .... excellent learning podcast 😊

[@davidjames6879]

Science wasn't anywhere this interesitng or cool when I was in school. Chuck is quick to pick up on all the nuances and Neil is beyond an great explainer! Thanks so much.

[@Gle7N]

I once flew from San Fran to Frankfurt on December, 31st. The flight is 11 hours, guess what we fellow travelers did.....we celebrated New Years 10 times, each time the new hour began.....😂

[@RK-tf8pq]

I think it would be more appropriate to celebrate the new year each hour if you travel from east to west, since, for example, the new year starts earlier in Frankfurt than in San Francisco. But even then since the Earth moves faster than the plane, you will be continuously falling behind after you celebrate the first time, or in other words, you would not make to any subsequent location at the exact moment of the new year for that location.

[@ray_ray_7112]

@@RK-tf8pq True, unless you were flying on the Concord, which is no longer in operation, mainly due to its sonic booms.

[@masoodkhan618]

If you from san fran to Frankfurt u will be flying from west to east. Even if u take the flight at 11:59pm on 31st when u r moving towards east ur going ahead in time if u flew one hour and as per time zone u will be 1 hr ahead of the time you depart anyway I give up explain I know u taking about people taking flight from Japan to sa

[@Gle7N]

@@masoodkhan618 I guess you're too nerdy to grasp the meaning of what I wrote

[@lolocarter7837]

Luv that! 🎉

[@Divemaster4122]

If Neil was my science teacher in high school I would never miss a day.

[@Greg-mu9kp]

Until he started taking about his identity politics

[@sandrataylor3723]

I just learned something new and I'm 67. Who says you can't teach an old dog a new trick, because Neil just taught me something. Thanks, Neil!

[@user-kw4iu8ge2w]

Right am 63 😊

[@ShawnRavenfire]

Another interesting fact. England, being a Protestant country, did not adopt the Gregorian calendar until more than a hundred years later, which meant that in the American colonies, the date skipped ahead eleven days, which is why George Washington's Birthday is celebrated on the 22nd, despite him being born on the 11th.

[@klaxoncow]

And Newton was born on Christmas Day, according to the Julian calendar that was in use at the time. Or a more boring January 4th by the Gregorian calendar.

[@FameyFamous]

That short year for England and the US was 1752.

[@troelspeterroland6998]

Tsarist Russia didn't adopt it until the October Revolution -- which means that the Soviet Union celebrated the October Revolution each November.

[@masheldon]

I was just talking about the abbreviated October of 1582 yesterday! Excellent timing!

[@sasikantht1658]

Very interesting coincidence! We want more of this from the internet and people!

[@RYTF5]

This vid is a repost. I remember it from a couple years back

[@mr.donkenny]

Someone else besides God should be listening to you.

[@wildhairsearch]

😂😂😂

[@davidletarte214]

omg chuck always cracks me tf up, "this is rome!"

[@EmpyreanLightASMR]

Guess what October. Dominusis spiratu: half the month is gone. lmaaoooo

[@stringtheory8090]

Chuck and Neil has such great chemistry

[@LHSlash]

I know exactly why we have Leap Days. I'm still watching. Because it is so great and I end up still learning something new. Always keep learning

[@MattIsntYoung]

I read "leap learning" 😅😂

[@dilanabey]

It's my son's 4th/1st bday this leap day! I'll have to show him this (maybe on his 2nd bday though...)

[@ggp53]

Thank you for your Intelligence, humor and down to Earth reasoning.

[@StarTalk]

Thank YOU!

[@unarealtaragionevole]

The 24 hr straight celebration we had on New Year's 2000 was something truly special. For those around to remember it, the hour by hour massive fireworks and celebrations was incredible, and then they cut them all into like a 4 hour feature film of nothing but grand finales......it was something truly amazing.

[@Person_2078]

I love this show, just wanted to say that, peace out

[@rodgar3759]

what i love about this is that in Futurama they added this fact and that's why even though Fry got frozen at midnight of new year's eve, he woke up at like 6 pm 3 thousand years later.

[@rgarlinyc]

NdGT, one of THE all-time best explainers of history and science. Period, 👏🏻

[@facespaz]

This was so funny and informational, thanks guys!

[@Aoderic]

Correction Neil, there are 38 time zones, not 24. Time zones are arbitrary man made entities, so they don't have to follow the whole hour. Thus, there are 14 zones that are offset by half or quarter hours.

[@timauth]

Interesting. Thanks for sharing. Like Neil, I just assumed that there was only 24.

[@zeroone8800]

The extreme time zones differ by 26 hours although the most behind timezone has no permanent population.

[@alexbeu3086]

Ha! Nice touch!

[@StarTalk]

Thank you for that correction!

[@ssaranillio]

There are 24 time zones in the world, each representing a different hour. 24 time zones are based on a 24-hour day. Each time zone is approximately 15 degrees longitude wide. Each time zone covers 15 degrees of longitude, meaning the Earth is divided into 24 different regions, each 15 degrees wide, for the purpose of determining time. Some regions and countries, however, have chosen to adopt a time zone that does not adhere strictly to these 15-degree segments due to various reasons, such as historical, economic, or political considerations. This can lead to variations in the total number of time zones when different sources are consulted. For example, the United States technically spans six time zones, but due to its territories and certain states like Arizona and Hawaii not observing daylight saving time, the total number of distinct time zones in the contiguous U.S. is actually four. Similarly, Russia spans nine time zones, but due to the vastness of the country and the adoption of the "Moscow Time" across several regions, the actual number of distinct time zones within Russia is eleven.

[@jennifertehanisarreal]

Came for Neil’s Star Talk and stayed for Chuck! They’re so great together!!! 👏🏼 👏🏼 👏🏼 🪐 💫 we need them on prime time television - so funny and educational. We need more of this. Awesome content.

[@MetaMan09]

PLEASE let the pod just flow and don’t cut as much, that’s the great part about podding is that you can just laugh and we laugh with you. When you cut it so much it makes the viewing experience not as good as it should be!

[@rashidxd]

In Persian calendar (Solar Hijri) which is the most accurate calendar that predates the Gregorian calendar, the first day of the new year (called Nowruz) happens on the first day of spring (21st March). I love the calendar mainly because of two reasons: 1) The first day of spring gives the vibes of a new earth, you see birds singing, flowers blooming, and you see everyone is happy with the big celebration (Nowruz). The alignment of the New Year on the first day of spring is quite underappreciated. (BTW, Nowruz was celebrated thousands of years ago on the first day of spring, long before the Solar Hijri calendar. 2) One of its greatest contributors of the calendar is Omar Khayyam, I love Omar Khayyam because he was not a theist despite being surrounded by theologians (his lack of belief is quite clear in his poetry if you can understand Persian, and that's something I personally admire). His poetry is legendary if you know Persian. Once translated though, it does not carry the same weight at all. He was an astronomer besides being a mathematician and a poet. Now that I live in the west, I don't get anything close to the New Year vibe I used to get. But that's a compromise for having freedom of belief here for me ;)

[@Ketraar]

As someone that grew up with the Gregorian calendar, already as a child I thought that placing the new year in this odd position was weird. Its just after Winter Solstice so at what you would intuitive feel like the end of a year. I mean we even have the expression of "winter years" for old people. Spring being the "rebirth" of nature always felt like the thing that made most sense to set a new year. I guess the reason is that back in the olden days the solstice defined the restart of the solar cycle, as in days start to get longer. And the celebration was afaik around 7 days so think the new year was just set at the end of those festivities and it kind of stuck.

[@thesaucepd]

I have three of you’re wonderful books my favorite is “to infinity and beyond” I hope you keep on sharing knowledge on this planet. 👍

[@charlessukati4866]

Beautifully explained by these two brilliant guys 🎉🎉🎉❤❤❤

[@juliannaschroeder6857]

Black History Month is in February because that's the month Black History Week was in (before 1970). In the mid 1920s, the Father of Black History, Carter G. Woodson, started Black History Week in mid February to coincide with the birthdays of Abraham Lincoln and Frederick Douglass.

[@nicholasharvey1232]

Did they really have to give the Blacks the shortest month to celebrate their history? It just sounds like an anti-Black conspiracy to me.

[@rajn7231]

Wow, but who asked?

[@user-kh1nq3qx6f]

Nobody just take it as a "Fact of the Day" and move on 😂

[@EricRoss57]

@@user-kh1nq3qx6f Thank you! Unfortunately, this site is also not free from nimrods.

[@juliannaschroeder6857]

They joked about Black History Month being the shortest month of the year, like it was some kind of ripoff. Listen at 3:47 when they call February "the neediest month."

[@AlonAbraham1]

This is my favorite video conversation😊 only can both of you guys can explain and entertain on a subject like this that i personallylike very much

[@yamilletrivas8041]

Hahaha! My aunt was born on a leap year. She has now passed but I wish she was around for me to tell her all of this! She would have loved it. 🥰

[@SiqueScarface]

But to be more precise, we have to take out the 400 year leapday every 3200 years. The year 3200 should not be a leap year.

[@xenos_n.]

Fortunately none of us have to worry about that.

[@cjrock4096]

If Gene Roddenberry's star date system catches, the leap correction will be a quaint memory of bygone days.

[@JohnC29]

Will we still be using the Gregorian calendar then? I don't think any other calendar system has been used that long.

[@rdspam]

Not part of the Gregorian Calendar nor ISO8601. The current orbit extrapolates to an extra day in 3300 years, but accounting for past and projected changes to earths orbit, it’s likely about 7700 years.

[@raghavendras4097]

​@@JohnC29"Pnchanga" India has been using it like forever so it's just uneven days and absolutely perfect years since the beginning.... Still been used for all religious timing.... I think that will be continued to be used

[@javieralejandroayala]

Thanks for sharing knowledge in that way!

[@anthonygordon9483]

I watch your channel and yes you talk about leap days all the time. Yalls laugh at the beginning seems to indicate that lol. But i love it anyways. Repetition makes for better knowledge and a friendly reminder. Keep doing it every leap year if you ask me

[@davidevans3227]

i do like it when they talk history.. thankyou for sharing this 🙂 x

[@orionthatman9390]

Chuck was killin the jokes on this one 😂

[@LupeCoded]

Dr. Tyson...bless you good sir. Just...bless you.

[@scottpayne4756]

Love you guys, i listen to you everyday anytime i drive for work.

[@Nefville]

I always thought it was weird that the day started in the middle of the night.

[@troelspeterroland6998]

Many languages have different words for "day" and "24 our cycle" (English technically has 'nychthemeron' but it's rather rare, unlike the words in those languages).

[@adhi.kusumo]

3:50 😂😂😂😂🔥🔥🔥🔥

[@EchosJourneys]

I love y’all. Thank you for teaching us in such a beautiful way.

[@donwarren8865]

I loved this! This explains it in detail that school never taught us.

[@EricJohnson-iv7ne]

Loved it! I never knew the origin of the Gregorian calendar. It’s great to learn something new every day.

[@hollywalker3726]

I just connected to why it's in February. The Julian calender begins in March.

[@juansehs94]

This explainer was amazing guys! Greetings from Colombia

[@MottoMotto_]

Thank you for sharing that information

[@IanCombs1337]

I appreciate this. Thank you.

[@user-kx8wb5ps9q]

Wow. I'm enjoying this. Thanks very much, guys.

[@tyrone4u559]

Excellently explained, thank you

[@DKMaester]

Love the editing.

[@wtpauley]

I love this duo, please never change.

[@EdgCerDlr]

Fun chat! Enjoyed it, laughed at it and learned from it!

[@lisacooke5928]

I tune in for Neil but Chuck makes the show😊

[@Marchelo1988]

This was so informative, thank you! I mean, everyone more or less knows about the leap day, but not so much about the 100-year and 400-year corrections! Awesome!

[@foreignshowreviews]

Fascinating thanks for sharing

[@GeoffreyWhite-ol9qq]

Always enjoy your teachings. Learning IS fun!

[@marianagyorgyfalvi3659]

Spring comes faster every year!

[@leatherface4133]

Loving them being in the office again together ❤❤❤❤

[@junkbox93]

The best trio of all time. Neil, Chuck and Physics.

[@heyits.queenie]

This is very informative!

[@NicholasMastroianna-hq6pl]

Thanks!

[@xtins]

I friggin love Neil and Chuck, I see you every time I can, but, this subject has the best video ever explained by Michael(vsauce) Tittle: How Earth Moves.

[@twilderlm2559]

Luv this Great Info / Fun

[@lexeiy1730]

So Informative 👏🏿👏🏿👏🏿👏🏿

[@p.d.6888]

This makes sense🎉 thanks yall

[@jessejamesdiver]

thank you always enjoy your podcast

[@tree_stabbing_troy]

My Grandfathers did. (1924) I remember in 2008 we had a big party to celebrate his 21st birthday and he was finally old enough to drink.

[@LaszloPalfi]

The final twist is (and it's a pity that Neil did not mention it) that the leap day is 24th February - not 29th February. The 24th day of February has to be "repeated" in every leap year since 1582.

[@oh_yeah_]

The thing that you judge a scientist by not telling u things he would not want to share because it would create more confusion for normal human beings is pity in itself. Why do you think he never ever mentions what time it takes “exactly” for earth to do one revolution around the earth? He always says “365days and little less then 6hours” (its actually 365days 5hr 48mins 45seconds) because he doesn’t want people to go on about what’s wrong with the Gregorian calendar, if you calculate you would find out (and this is an actual limitation of Gregorian calendar) that after about 3200years you should take away a leap year because it overcorrects it (he knows this) he just doesn’t want people to think much and understand whats normalised now like all other scientists My point is… not everything he doesn’t tell and knows means he is doing it for no reason

[@Emmybankz]

Please kindly help me understand what you mean

[@LaszloPalfi]

@nkz In 46 B.C. Julius Caesar as High Priest reformed the calendar. It was necessary because at that time the calendar was already 3 months ahead of the rotation of our planet. The year the Julian calendar came into force became the longest year in history, as the 46th year before the birth of Christ was 445 days long. This was the only way they could bring the calendar into line with astronomical observations. The Julian calendar was the first one that contained 365 days, which were extended to 366 days by repeating one day every 4 years. The repeated day was then February 24. Since then, the 24th day of February has been repeated every leap year, which makes the days from 24 to 28 move forward in time. In short, the inserted leap day is not February 29, but the repeated February 24, the reason for which is the preservation of ancient Roman traditions.

[@Emmybankz]

@@LaszloPalfi thank you so much

[@ericbauer4559]

I celebrated new years this year flying from the east coast across Atlantic. Hit midnight a few times in the air.

[@anurag01a]

It's a skill to explain complex things in such a jolly mood. Chuck makes it funnier!

[@janmangu399]

I love this dou. Neil is a science man but he explains every thing in so much simple ways. Chuck who represents us in the video don't know any complicated stuff but still gets it with the easy explanation of Neil. I still remember the time relativity and the carbon dating videos those are best explanations.

[@maxenielsen]

Great explainer! Thanks!

[@divinelyguided1144]

Very interesting 🤔 thank you 🙏🏾

[@untrainedastronaut]

I absolutely love your stuff.

[@garygemmell3488]

I first found out about the 400 year leap day when I was in the 7th grade but the way I understood it was that an extra leap day was added to February which meant that every 400 years February would have 30 days. The part about not adding the leap day every 100 years was left out. So, the year 2000 was divisible evenly by 100 which meant that there would be no leap day. BUT, in was evenly divisible by 400 which meant the leap day was put back in. Now I know why February, 2000 did not have 30 days in it like i was expecting. I was kinda of looking forward to February 30th for the only time in my lifetime. Great show. You truly are our personal astrophysicist, Neil.

[@haroldcook5360]

Awesome too hear about!!

[@williamphiri1067]

Explained easily. This is how explaining should be.

[@mannym7849]

Aww you two are just sooo funny and you make learning so much more enjoyable and exciting. I love the energy between you and I’m sitting here in giggles. Thank you both so much and keep making learning fun 😁🤣🤣

[@marymendoza3351]

It was good to hear a tutorial about Leap Day

[@TiTaughtYou]

This was so dope! 💫

[@nathanieljackson5554]

Great explainer on why it's called the Gregorian calendar.

[@uuakata]

thank you so much very interesting

[@Quonok]

Thank you

[@kincamell2]

Gratitude

[@hfadavi]

In Persian year that 5 hours and fifty something minutes and seconds is calculated to celebrate every new year. So the time to celebrate new year is different every year.

[@kunalsinghal1247]

To be honest that would be easier. All you need to account for is an extra number of hours. Here we are actually playing with days to compensate 😅.

[@sameera_viraj_K]

Love you two Guys. Specially Neil. You are my favorite Astrophysicist im have watched almost all the documentaries that you were in. What a legend. Keep it up 😍❤👌

[@stevegonzales7295]

That was an amazing explanation. I must’ve been sleeping during the lesson in school.

[@edgardguzman]

Great explainer Dr Tyson!!!

[@FlyingDwarfman]

That final point leads me to something amazing. Just imagine the whole planet celebrating an agreed-upon exact moment -- regardless of time zone -- as the beginning of the New Year. Will it, would it, */could/* it happen? I don't know. I'll just sit here and imagine it for a while.

[@dinglemccringleberry9019]

Celebrating the new year during the day? I assumed it be cooler that they'll instead use confetti tipped fireworks. An also, since it's daylight you can see things in the sky much clearer than nighttime. So, flybys would be a thing, so almost like incorporating parade style celebrations. Imagine the entire aircraft fleet of the entire country doing a flyby or at least a huge number during the event due to size of airspace they can restrict.

[@MelanieGraceTV]

Honestly, the laughter is the absolute best!😊

[@JutahFate82]

I learned something new and laughed out loud 😂

[@mus0075]

Can’t imagine an explainer without Chuck😊

[@jamaaldupree7371]

Always 🔥🔥

[@carloscurrea3994]

Thanks for such a great explanation, I’ve always had these 2 questions about leap years, though: 1. Why it has to be in February? 2. Why we don’t have 2 months with 29 days, but we only have 1 day with 28 days? How did we get to that? Thank you again!

[@nala_b]

Enjoyed this

[@brooklyn5755]

This is impressive ❤

[@mercedes4328]

Wow!! Best explanation EVER! Although I didn't understand that 100 and 400 year thing.

[@Eric1396]

That was awesome!

[@stevecox4534]

You make me laugh! I love it!

[@kwabenaedwards]

This is one of the best explaners I have listened to

[@samuelodey9823]

Thank you, Neil. Thank you, Chuck.

[@petersage5157]

Okkay, less than 20 seconds into this video, I can give Neil an emphatic "Yes, you've already done this as a Neilsplainer." It opened with Neil asking Chuck how long a year is and proceeded through the Leap Day algorithm in the Gregorian Calendar. (By the way, even with these adjustments, we'll still be off by a day in a few thousand years, but considering the relatively short lifespans of civilizations, it's close enough.) I think there was also a bit about solar and sidereal time.

[@floydrazor]

This is really great.