Neil deGrasse Tyson Explains Why We Have Leap Days

[@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

[@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 🙌🏾

[@JosephMiller-u3t]

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.

[@Nunya_Bidnez]

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

[@Eneov]

The universe needs Chuck.

[@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......

[@mzhappyfree7688]

I agree. I love these two together

[@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! 🎉

[@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.

[@Lizizbeautytarot]

😂😂😂

[@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!

[@JosephMiller-u3t]

Right am 63 😊

[@LaughAlil]

Feel the same way sir thank u Neil

[@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.

[@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

[@paulorganisation1]

And you wouldn't have failed😂

[@stringtheory8090]

Chuck and Neil has such great chemistry

[@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.

[@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.

[@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...)

[@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.

[@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.

[@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" 😅😂

[@rgarlinyc]

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

[@ggp53]

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

[@StarTalk]

Thank YOU!

[@davidletarte214]

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

[@EmpyreanLightASMR]

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

[@Person_2078]

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

[@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.

[@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?

[@FoodFromTheHornCA]

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

[@EricRoss57]

@@FoodFromTheHornCA 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."

[@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. 👍

[@hollywalker3726]

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

[@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

[@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!

[@heyits.queenie]

This is very informative!

[@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.

[@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

[@SiqueScarface]

@@raghavendras4097The Panchangam calendar works differently. Instead of pre-calculated corrections, it inserts an additional (lunar) month each time the calendar New Year differs too much from the astronomical observation. That's why it is correct in the long run - it just adapts the calendar retroactively. The predictive power but is rather small.

[@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

[@EchosJourneys]

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

[@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

[@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!

[@gary-williams]

11:50 "There's 24 time zones..." Actually, there's at least 38 time zones. Some jurisdictions are offset by fractions of an hour. These fractional time zones can be found in India, Australia, New Zealand, Canada (Newfoundland), Sri Lanka, Afghanistan, Iran, Myanmar, Nepal, and French Polynesia. Incidentally, the ancient Romans inserted Leap Day on February 24, rather than on February 29.

[@0biwan7]

yes. i'm not sure if neil is mistaken or just lying to us so as to keep things simple from a teaching perspective.

[@christellefrancios2038]

I think he knows that .. that’s why he said well at least 24 slices of the earth .. but for the point of these video to simplify the idea.

[@davidevans3227]

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

[@isatousarr7044]

Leap years are crucial for maintaining alignment between our calendar system and the Earth's orbit around the Sun. A solar year is approximately 365.2425 days, so adding an extra day every four years helps correct the drift that would otherwise accumulate. This adjustment ensures that seasonal events remain consistent with the calendar year. How might advancements in our understanding of Earth's orbital dynamics and cosmic cycles influence future refinements in our timekeeping systems?

[@orionthatman9390]

Chuck was killin the jokes on this one 😂

[@charlessukati4866]

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

[@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).

[@uneep7406]

Excellent insight on leap day. My question is why does it fall in February and not in any other month ? If you can explain in a video or reply 🙂

[@candicecandy8137]

I love how they're giggling like school girls throughout🤦🏾‍♀️😂🤣

[@barbarossarotbart]

Nitpick #1: Leap days (which BTW existed even before the creation of the Julian calender, but did not have clear rules) were always put at the end of the year. During the late Roman Republic the year began with the first day of march. (BTW this is also the reason why february has less days than any other month, because every time the number of days of a month was increased from 30 to 31 the additional days was taken from feruary) Nitpick #2: Pope Gregory's concern was not that Easter and passover could coincide. His main concern was that Easter would come so early in the year that it were still winter. The removal of those days to synchronize the calender happened in October because because these day were no important days in the christian lithurgical calender.

[@adhi.kusumo]

3:50 😂😂😂😂🔥🔥🔥🔥

[@EricJohnson-iv7ne]

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

[@EdgCerDlr]

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

[@IndigenousScience76]

Super amazing man. I just love how deliver on your presentations regardless of how complex the topic would seem to be. My Physics Professors back in Univ never gave me me such detailed understanding. You are such a genius a Physics Champ

[@donwarren8865]

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

[@GeoffreyWhite-ol9qq]

Always enjoy your teachings. Learning IS fun!

[@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 😅.

[@chenjidanceteam]

Wow! You just answered this thing that bothered me a long time that the extra distance was precisely 1/4 of a day. Of course it’s not! Thanks!!! I’m so hooked on this channel and subscribed to patron ❤

[@kyazs2707]

If I were the energy that controls all consciousness in the universe, then I would have the privilege to bestow these awards upon Mr. Neil deGrasse Tyson for the following: 1. Most likable astrophysicist. 2. Most likable Hollywood star. 3. Most likable KZbin star. 4. Beyond genius. 5. Remarkable astronomical career. I simply enjoy startalk! Thank you. .

[@Akaawol]

There are more than 24 time zones. Currently, there are 38 different local times in use worldwide, each defined by its UTC offset

[@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.

[@zax8914]

As someone with a Catholic biological family that was raised by a Jewish adoptive family that went to Jesuit university (Xavier in Cincinnati) I'm still trying to figure out the one or two Adars, seemingly arbitrary extra days and the Hebrew calendar. Orthodox Easter? Regular Easter? I've never celebrated Easter except a couple times. I use a Jewish calendar from the Jewish Museum of New York. Weekly planner. Groundhog Day as a halfway between winter and spring (Feb 2nd)? We just had Purim Katan. Coming up regular Purim. Passover next.

[@juansehs94]

This explainer was amazing guys! Greetings from Colombia

[@lisacooke5928]

I tune in for Neil but Chuck makes the show😊

[@RandonMyles]

This has been a topic of mine at parties for years. For some reason I seem to get fewer and fewer party invites...

[@0biwan7]

what happened? they sent you an invite for a party on march 21 and everyone but you showed up on march 9?

[@ericbauer4559]

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

[@MottoMotto_]

Thank you for sharing that information

[@XE-4]

Extending this calculation further, beyond 4, 100 and 400 year cycles, should we not skip a leap year every 1,600 years but then put it back in every 6,400? So should we not have skipped the leap day in the year 1600? And should the leap day in the years 3200 and 4800 also be skipped (assuming humans survive that long) before we add it back for the year 6400?

[@LupeCoded]

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

[@scottpayne4756]

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

[@anurag01a]

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

[@missh1774]

That was more than expected. Thanks guys. Can you also give another one of these explainers for the international timeline and why Germany is 10 hours behind at 6 AM to NZ's 6 PM today. What happened to Greenland? Has the time been corrected due to the tilt and rotation of the orbit? And why does the shoe crinkle appear in some maps and not in others? Please sort this out in my brain for me. Thanks guys!

[@mick1287]

This was a fantastic explanation. Thank you both! What I would love to know is why February only has 28 days to begin with? Why not take some of the months with 31, make them 30 days long, and voilà, February has 30 days, too!

[@cbsteffen]

I think the number of days in February goes back to the early 10-month Roman calendar which started in March. Sextilis (which is now August) had only 30 days, and so did December. I think Sextilis and December each gained a day when Sextilis was renamed August (which might have been on the first 12-month calendar). That’s the best guess and answer I can give.

[@barbarataylor6979]

😊8 did learn this in school and I am 72 but I don't remember why Easter sometimes is during the month of March or the month of April.

[@PuzzledMonkey]

en.wikipedia.org/wiki/Date_of_Easter The computus is an ancient calculation designed to approximate the first Sunday after the first full moon of spring. Except that it assumes that spring is always on March 21 (which it isn't). This usually but doesn't always align Easter to occur during the Jewish holiday of Passover, but it doesn't always, because the Jewish calendar had itself drifted over the last two millenia, and occasionally adds a leap month when it shouldn't, as it does this year.

[@barbarossarotbart]

@@PuzzledMonkey And that's the reason a part of Neil's explanation is wrong.

[@PuzzledMonkey]

@@barbarossarotbart Exactly. He said they tried to avoid Passover when in fact it was the opposite.

[@ggp53]

So when I first thought about this question and before I actually watched the whole interview I thought for just a minute and asked myself if we didn’t have a leap year we’re either gonna gain time or lose time and it sounds like we would lose time so spring after so many years would become winter and then after so many more years spring would rotate to the to autumn/fall position and then eventually become summer and then back to fall again, correct? If so, my question is how long, how many years, would it take to cycle through that process, how long would it take fall to cycle through and become fall again?

[@ggp53]

Oh yeah, what I really love about your channel and a major reason I like to watch it is because it takes my mind off of the insanity of the world we live in. Thank you for explaining things so that an average person can grasp/understand complex issues.

[@williamirwin4154]

In the spring of 2000, I was taking a class in college called Sun and Solar Systems and I learned this information just a few weeks after the 2000 leap day occurred. It's still my favorite fun fact to tell people.

[@mustlearnmore4884]

11:50 I think there's actually 25 timezones, as Newfoundland has their own special timezone that is 30 minutes different (as opposed to a full hour) to its nearest timezone neighbours.

[@fromnorway643]

There are some other special cases, too. Iran is +3½ hours, Afghanistan is +4½ hours, India is +5½ hours and Nepal is +5¾ hours ahead of Greenwich time. And finally, the Australian states South Australia and Northern Territory are +9½ hours while a tiny part of Western Australia is +8¾ ahead of Greenwich time.

[@user-kj8di3qf4z]

Admittedly, I did not listen till the end. But I’m curious if there is a specific reason the end of February was chosen to put the extra day. Is there a reason why it couldn’t be on the end of September or on the end of May?

[@untrainedastronaut]

I absolutely love your stuff.

[@billsikesliberation2490]

We were thought a Rhyme: 30 days have September, April , June and November. All the rest have 31, except February alone which has 28 or 29 days in each leap year.

[@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.

[@junkbox93]

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

[@javieralejandroayala]

Thanks for sharing knowledge in that way!

[@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.

[@robertcagle6156]

My mother several years ago that leap year only happens on years that are divisible by 4. This is interesting!

[@0biwan7]

she is correct. however, just because every leap year is divisible by 4 does not mean that every year divisible by 4 is a leap year.

[@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!

[@manuelmoreira8575]

What another amazing episode!

[@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.

[@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.

[@mercedes4328]

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

[@farmergiles1065]

Speaking of the Roman Senate, Chuck, why is New Year's Day on January 1st? In parts of Europe, it was March 25th for a time. But that was temporary, and it went back to January 1 eventually - because that was the day the Roman Senate met for the first time in the year. It was the day all appointees took their office, so it was the day of the change of administration. Now, the Greek scientists who invented the Julian calendar in 46 B.C. knew the year was about 365.25 days long, also from just watching the sky. So they set it up for one leap day every four years. However, the Roman Senate wouldn't leave well enough alone. Appointees every fourth year got an extra day to their term of office, and everyone wanted in. So for a while, leap days had to be approved by Senate vote. And guess what? Three years apart. Five years apart. It was messy. That's the Senate for you. And it caused big problems for government, legal cases, etc. So eventually the Emperor put an end to that senatorial authority. And that, plus the extra leap day each century, is how the equinox ended up on March 21st when the Church adopted its official Easter calculations (around 550 A.D.). In Julius's time, the equinox was more like March 25th. How do we know? Because the pagan holiday of Sol Invictus fell on the winter solstice, and that was December 25th. And way back, that's why the Church assigned Christmas to be celebrated on Dec. 25th. Because you had to choose which holiday to observe. Be Christian, or be pagan. Maybe you didn't want to know all that, and many wouldn't, but hey, I'm something of a geek.

[@AnweshanAnweshan]

A request to Dr. Tyson: Would you please throw some light on calenders from other cultures and how they tried to solve this "leap day" problem. A few examples of other calenders be the Mayan, Chinese, and Hindu calenders.

[@andrelanabr9886]

We can accelerate a particle in earth so that 1 hour for it equals 10 hours for us. Can we somehow slow down something in earth so that 10 hrs for it would be only 1 hrs for us? If hypothetically yes, could someone enter a machine, slow its velocity, sleep for 10 hrs and come out of the machine actually only "one hour later" (according to the time of the rest of us) fully recovered and ready to start a day again?

[@JayChannels]

@StarTalk How much faster or slower would earth need to rotate to get exactly 365 days to fit into the year?

[@carultch]

A day would need to be 7 minutes and 37 seconds longer, to get exactly 365 days in one year.

[@carultch]

@@MrT------5743 Reread the OP's question. The OP wasn't suggesting a change to the year length, the OP was suggesting a change to the Earth's rotation rate. Presumably keeping the year length exactly the same.

[@carultch]

@@MrT------5743 The year is 5 hrs & 49 minutes longer than exactly 365 days. If you wanted to change the day length to make a year exactly 365 days, this means you need to make the day longer. You need to take that 5.82 hours, divide it by 365, and then add it to the existing 24 hours. And that's precisely what I did.

[@nathanieljackson5554]

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

[@kathy9542]

Q. Since Easter isn’t a problem for everyone, for example what did the Chinese do? I understand that the Indian calendar and the Jewish calendar are similar. What do they do?

[@randelldickerson6147]

That was dope. Very smooth delivery. I definitely learned something .. I still think THE MAN pulled one on us😅😅😅

[@mazyars.2516]

Persians are doing the same for the last 2500 years. Khayyam or jalali calendar or in other words the ancient Persian solar calendar is one the oldest and the most accurate calendar in use today. 6 hours will be counted on the first day of each New Year and it works fine.

[@kadirer690]

I've a feeling that putting leap day back in every 400 years still over corrects earth's revolution around the sun

[@johntracy72]

It will in about 3300 years.

[@Phelix.Adjei.Junior]

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

[@arold8839]

hye sir, i got a question 1- how that the ancient Rome found out about this matter back in the days? 2- how did there count 1 year (365 days) is to complete a circle. how there measure back in the days? sory for the plain question.

[@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.

[@coder001]

I had to watch this a few times it's so confusing: 1) Earth rotates around its axis once a day 2) Earth orbits around the Sun 1 year plus 1/4 Earth's rotation on its axis (this 1/4 is 6 hours) * * So its uneven * * * Every 4 years it adds up to a 1 day 3) Ancient Rome Julian Calendar decided to "pocket" the 6 hours every year then just add 1 day every 4 years 4) But there's more, it turns out it isn't an extra 6 hours exactly, it's a little less * * Over the centuries there were days accumulated that were not accounted for (remember cause it's not exactly 6 hours) * * * This has a side effect of events happening sooner during the year than expected ** * * For ex: If not corrected you would eventually have winter in June (in the US that is) 5) To fix the Calendar the Pope took out 10 days 6) To fix the problem every 100 years take out a leap day 7) But that isn't a complete fix because it under corrects it a bit 8) To fix the under correction every 400 years you have to put a leap day back in

[@foreignshowreviews]

Fascinating thanks for sharing

[@RajuRavindran-ro7xr]

I want to know how do the people who used the calender 2000 year ago knew about these details that earth took 364 day and 6 hours precisely to complete one revolution..

[@aungsatt7169]

First of all people from 2000 year ago didn’t know. They based calendars on seasonal shifts since the same season will likely to come back when earth revolve a complete circle around the sun. And it was correct, for a short term. But after a certain period of time, they started noticing seasons are not align with the calendar anymore, so they revised the calendars for multiple times across the centuries until the gregorian calendar. Fun fact though, Gregorian calendar was reformed from Julian calendar. The motivation for the adjustment was to bring the date for the celebration of Easter to the time of year in which it was celebrated when it was introduced by the early Church. Because the date of Easter is a function - the computus - of the date of the spring equinox in the northern hemisphere, the Catholic Church considered unacceptable the increasing divergence between the canonical date of the equinox and observed reality. Easter is celebrated on the Sunday after the ecclesiastical full moon on or after 21 March, which was adopted as an approximation to the March equinox.European scholars had been well aware of the calendar drift since the early medieval period.

[@tyrone4u559]

Excellently explained, thank you

[@Weezedog]

Neil, you did actually go over this back on Oct 17, 2023 in the video “How Long Is A Year, Actually”.