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What is a Leap Year?

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Text Comments (3988)
David L. (2 days ago)
"that refuses to be divided nicely" except by 13 with just a solitary New Year's Day left over! i realize that this is almost never going to happen now because of how incredibly disruptive it would be to the everything, but if i had the opportunity to design the calendar system from scratch, i'd make it thirteen 28-day months with a monthless New Year's and Leap Day tacked on at the end/beginning. you could even keep seven-day weeks and days would land on the exact same dates every month. while having the New Year's and Leap Days also be "dayless" would certainly be in keeping with the tidiness of the system (so that you could reuse the exact same calendar every single year), i can also see the appeal of the days getting offset by 1 each year just for a bit of variety. with the inclusion of the Leap Year day, now i kinda want to crunch the numbers now to see how long before days land on the same date again in this system... or how long the whole cycle takes to repeat...
Will Hill (3 days ago)
Interesting fact, if we made all months 28 days, we could have 13 months in a year
Mister Jibril (4 days ago)
You sound like vladtv
Spygon (5 days ago)
Austin sent you?
Wendy_1995 (13 days ago)
Where are my people that have been born on a leap year? I wanna know more of my people XD
B Moo (13 days ago)
1:40 Dont think I dont see that creeper
Fire Feather (13 days ago)
Why not just change the number of sec. Are in a minute? That way those 6 hours can be accounted for?
lonelyPorterCH (14 days ago)
So thats why :D
BGMC 16 (19 days ago)
And tomorrow will be February 29th, 2012!
Turtle Squirrels (25 days ago)
I think the mathematicians did a pretty good job if it only one day off in 8000 years
Eli Egbert (27 days ago)
3:12 China's giant hydroelectric dam must've had NOOOOTHING to do with that...
Joseph Cahill (1 month ago)
There are four frequent types of years to be born in there are leap years (1904 1908 1912) 1st common years (1905 1909 1913) 2nd common years (1906 1910 1914) and 3rd common years (1907 1911 1915) Then again there are fourth common years but fourth common years are very very rare and unlikely fourth common years only happen once every hundred years because everytime we start a new century we skip a leap year unless its divisible by 400 1700 1800 1900 were fourth common years meaning that those next three years are 5th 6th and 7th common years but once you go to the fourth its back to a leap year however 2000 WAS a leap year beacause it was divisble by 400
MP Hughes (1 month ago)
What game/software is 1:22?
Guy Geva (1 month ago)
3:28 Vsauce conifrmed
Madeline Cook (1 month ago)
People in Wisconsin are already prepared for the season switch, this year winter didn't end until the middle or end of spring. Sigh.
Patrick Games (1 month ago)
P I like it how do you make those videos. Who do the ammunition up at the spring and winter winter in July and spring in September how do you make the ammunition so good you’re the best makes keep it well
Elijah Ford (1 month ago)
The sun doesn’t expand until the year 5,000,000,000. And by that time the human race has already mastered interstellar travel, and has left that dumb rock behind years ago. Of course, some people don’t count those humans, but those people are just a bitchy trampoline.
Maria Duarte (1 month ago)
3:19 in theory the length of a day will expand to be as long as the current month but don't worry in practice it will take tens of billions of years and our own expanding sun will destroy us long before that happens. WHAT!?!
Maria Duarte (1 month ago)
Maybe you can skip the "divisible by 400" rule if it is divisible by 8,000, then it isn't a leap year. What's the error?
Patrick Games (1 month ago)
Why does season flip?
LorenzoP Games (2 months ago)
Why is everyone north-centric?
T_Nation (2 months ago)
I like the 13 month calendar Kodak used to have: every month 28 days, every date on the same say of the week, and a bonus day on new years.
Xaverderschnitzelfan (2 months ago)
Why not a calander wich is based on some distant constant and light speed, every time light passes this constant one time passes by. And as an extra the time of the day . Means after x hours its the date 9342.582 16:43
Poodro Fartman (2 months ago)
what if you're born on february 29?
its mme alfie (2 months ago)
If you don't know what autumn is it's fall how ik is because I live in the UK fall is autumn in uk
Gamemastershy (2 months ago)
I live in Australia and Christmas is celebrated in summer
Akhsan Hakim (2 months ago)
what's on 3:05
Sebastian Stan (2 months ago)
0:53 Weird flex but okay.
Sebastian Stan (2 months ago)
What is a leap year? What is not? Find out in the next day of Dragon Ball Z
Finile (2 months ago)
What happens if someone is born on the leap year? Aka What happens if the person is born on the day that was added to February?
Pen L (2 months ago)
then they would be 5 years old while you are 20 years
Emma Woolnough (2 months ago)
Hey, I’m actually learning something
Feynstein 100 (2 months ago)
Oh and since our aim is to not drift out of the seasons, the precession of the equinoxes, a 26,000 year-long cycle, will have to be incorporated into the calendar as well, so that we don't go out of sync.
Feynstein 100 (2 months ago)
Hmm but don't we run into the same problem while counting the days themselves as well? The earth doesn't take exactly 24 hours to rotate on its axis. It's 23 hours and 56 minutes, leading to an error of 4 minutes per day. And so in 15 days, the total error will amount to 60 minutes i.e. an hour. And in 360 days, we'll be off by a day. Why doesn't this happen?
idk idk (2 months ago)
398 Flat-earther were triggered by this video
Idkag 4 (2 months ago)
Huzzah! The problem has been solved. Except it hasn't. Lengthening the calendar by one day every four years is slightly too much, and the calendar still falls behind the seasons at the rate of one day per hundred years. Which is fine for the apathetic, but not for calendar designers who want everything to line up perfectly. To fix the irregularity, every century the leap year is skipped. So 1896 and 1904 were leap years but 1900 wasn't. This is better, but still leaves the calendar ever-so-slightly too fast with an error of 1 day in 400 years. Do an additional clause is added to skip the centuries rule that if the century is divisible by 400, then it will be a leap year. So 1900 and 2100 aren't leap years, but 2000 is. With these three rules, the error is now just one day off in almost eight thousand years which the current calendar declares 'mission accomplished' and so calls it a day. Which is probably quite reasonable because eight thousand years ago humans were just figuring out that farming might be a good idea and eight thousand years from now we'll be hopefully be using a calendar with a better date tracking system. But perhaps you're a mathematician and a 0.0001 percent error is an abomination in your eyes and must be removed. "Tough luck" says The Universe because the length of a day isn't even constant.
JeSuisCereidee (2 months ago)
I'm more confused.
Asterizy (3 months ago)
Next Leap Year: 2020
Festus Jackson (3 months ago)
Boss-? You Rapping man? Say what now?!🤦🙍
Zach Allonby (3 months ago)
2:53 Did anyone else notice that he is holding a game boy?
Evatan (3 months ago)
I saw that gameboy
Tilde (3 months ago)
Don't forget leap seconds https://en.wikipedia.org/wiki/Leap_second
Philippinesball (3 months ago)
i was almost born on the 29th lol
Deaster (4 months ago)
If I was born 2 hours later I would have been born on leap day.
Cotten bud (4 months ago)
1:20 celestia and Luna’s cutie marks I think we got a mlp fan
Pixel (4 months ago)
Wasn't it something to do with the romans? They thought February was unlucky and gave it less days or something.
Kalan Saunders (4 months ago)
Crismas is in summer you suppid
Pen L (2 months ago)
please learn that the Northern Hemisphere it’s winter while in the Southern Hemisphere it’s summer and please learn to spell stupid right.
Yeboyizac K (4 months ago)
Ben Kleve (4 months ago)
Wow my half b day
Eric Prater (4 months ago)
Seven days in a week? Fifty two weeks in a year.? Three hundred sixty five days in a year? So .... 7X52=364 WAIT WHAT JUST HAPPENED??!?
Ekmek Arası Balgam (5 months ago)
What if someone born in february the 29th?
Real RedSheep (5 months ago)
but new Zealand celebrates Christmas in summer
Brett Delport (5 months ago)
So oracle database counts 2 less days since 1900 than excel does - wonder why.
evan saenz (5 months ago)
Did anyone notice the creeper in the car in front 😂 1:34
Pao Lol (5 months ago)
My head hurts
MrUltimategamer44 (5 months ago)
Something tells me a ballerina would fall off a truck. 🤔
Temesgen Abraha (5 months ago)
1:27 flat earthers triggered
Preston Helling (5 months ago)
The sun is a deadly laser
Matthew Mazzetti (6 months ago)
They should just make it ten months and get rid of July and August.
Matthew H (6 months ago)
Recommendation squad where are you at?
spart icuz (6 months ago)
We should create a calendar with 5 day week, it would be much better.
Michael Best (6 months ago)
I'm wondering why the people that created the calendar didn't give February 30 days. Take 2 days from one of those months that have 31 days. This video doesn't talk about how Feb only has 28 days! Like poor little dwarf planet Pluto, I guess! ? Maybe I'll find out why Feb only has 28 days somewhere else.
september1717 (6 months ago)
We could of had 4 weeks each month of we had 13 months, then add 1 day per 4 years
Tristan Laing (6 months ago)
Ok, but was there ever a 365 day calendar? Didn't the Julian calendar have a leap year when first adopted?
TheBrazilRules (6 months ago)
I don't understand this desperation people have with bailing from the planet. It is irrelevant to worry about the Sun's expansion for 2 reasons: First it is going to take a lot of time to happens, so who should really be worrying about this is people from 9 billion years on the future, since they will have at least a billion years to figure this out, and second, if we are successful we are just delaying the inevitable since we can't escape the end of the Universe's entropy. If you are worried about humans destroying the world themselves, maybe we deserve to be extinct.
Foxy The Pirate 2019 (6 months ago)
My dads born on feb 29th
Seamus McKeon (6 months ago)
13,000 years from now, the seasons will reverse begins the north will face Vega instead of Polaris.
Ananth Yegavakota (6 months ago)
I'm born on February 29 lolol
Jacopo Lattanzio (6 months ago)
Today is 29 february 2019
Roy Adair (6 months ago)
🐸🐸Leap year is when the frogs feel froggy and multiply... lol. Actually , it is an extra day in February every fourth calendar year. Thank you Mr. Grey for the Scientific and mathematical explanation for Leap Year. 👍👍 Oh Mr. Grey ...Have you dissected Kermit the frog yet? 🐸🐸Ribbet croak craok ...
Ben Deoleveira (6 months ago)
Seyed Reza Miraskarshahi (6 months ago)
Hopefully be using a calender with a better tracking system? It's already been invented. It's called persian calendar!
Magister (6 months ago)
What about 1400 and 1500, they are divisible by 100 but still a leap year!
NiceRazer (6 months ago)
I came from exercism
itsZinZin W (7 months ago)
I was taught that one day is 86 400 seconds, where one second is 9 192 631 770 oscillations of the radiation corresponding to the transition between two levels of the caesium atom.
pvz 25 (7 months ago)
At 0:19 that is the same length
the.abhiram.r (7 months ago)
Just celebrate new years at 6 am
Christian Jiang (7 months ago)
So now it’s February This video just reminded me that February is 28 days long. Hurray! It means that this term will end earlier than expected!
Abhishek Lande (7 months ago)
I knew this but had to watch to see the CGP grey view on this
MikeAiyo (7 months ago)
Ok so, I was born on Feb 29 2008. I am 2, in leap years But hypothetical for you,if I were to delete my birthday from the side of earth I don’t know if I would be born on Mar. 1, or Feb 28. And more questions of why the hell humanity is still sitting here not helping earth.
Matthew Burggraaf Vlogs (7 months ago)
So technically, (Say im 20 years of age), Im actually many years OLDER than 20 or many years YOUNGER than that. People born in leap years fell discouraged and confused about they're age. But to all those leap year babies...… Everyone is going through the same issue.
somaru shinde (7 months ago)
this is fake every one knows the sun is squar
rommel plana (7 months ago)
Tanja Scekic (7 months ago)
Denizo italano (7 months ago)
leap year=extra day at school
Ubeyd Yilmaz (7 months ago)
I still don't understand it
TMP Playzz (7 months ago)
A 0.0001% offset is INACCEPTABLE I can't pass it!!
Tom (7 months ago)
Thanks Grey for taking the time to fix your videos from the Annotation Obliteration
DweebTeambuilder Jones (7 months ago)
3:35 That won't matter. Humans have at most another eight million years. Eukaryotic life is scheduled to die off in 800 million years (because the sun's increasing luminosity will freeze plate tectonics and thus destroy the carbon cycle), and all life will die out two billion years after that when the habitable zone fully clears Earth's orbit. By the time the Sun expands past Earth's orbit 7.6 billion years from now, Earth will have been a dead world for about 4.3 billion years.
The Physicist Cuber (7 months ago)
Thedoctor133 (7 months ago)
Why don't we give February 30 days like we have the extra days to make up for it.
MvB (7 months ago)
This is fake, cause the earth is flat!
zachary viray (7 months ago)
rip people born on feb 29
James Harrison (7 months ago)
So what I got from this was... Fund NASA. Close enough
Malaysia Ball (7 months ago)
1:41 there is a creeper in the car dO Grey play Minecraft?
clncrvl The Inkling! (7 months ago)
Who saw the creeper in the car at 1:33 ?
Remlala Sailo (8 months ago)
Talking too fast
Game loft Country (8 months ago)
It’s terrible to celebrate Xmas in summer and trust me I live in australia
Bryce Edge (9 months ago)
leap years are years getting hard
Tyler Shallue (9 months ago)
If you say February 29, 2100 to Siri on your iPad, it defaults to March 1. Lol.
Niky (9 months ago)
In south america chrismas is already in summer ;-;