Why Do We Have Leap Years?
Vložit
- čas přidán 28. 02. 2016
- So it's February 29th and we have 366 days this year instead of 365- what's the deal with Leap Years?
----------
Support SciShow by becoming a patron on Patreon: / scishow
----------
Dooblydoo thanks go to the following Patreon supporters -- we couldn't make SciShow without them! Shout out to Justin Ove, Fatima Iqbal, Linnea Boyev, Kathy & Tim Philip, Kevin Bealer, Justin Lentz, Chris Peters, and Philippe von Bergen.
----------
Like SciShow? Want to help support us, and also get things to put on your walls, cover your torso and hold your liquids? Check out our awesome products over at DFTBA Records: dftba.com/scishow
----------
Looking for SciShow elsewhere on the internet?
Facebook: / scishow
Twitter: / scishow
Tumblr: / scishow
Instagram: / thescishow
----------
Hosted by: Hank Green
Sources:
scienceworld.wolfram.com/astro...
www.britannica.com/science/Bab...
scienceworld.wolfram.com/astro... books.google.com/books?id=5O7...
www.wolframalpha.com/input/?i=...
www.wolframalpha.com/input/?i=...
penelope.uchicago.edu/~grout/e...
www.livius.org/articles/concep...
www.gutenberg.org/cache/epub/1...
www.newworldencyclopedia.org/e...
www.wolframalpha.com/input/?i=...
www.biblicalcatholic.com/apolo...
www.britannica.com/topic/pontifex
www.wolframalpha.com/input/?i=...
www.wolframalpha.com/input/?i=...
adsabs.harvard.edu/abs/1992JBA...
www.wolframalpha.com/input/?i=...
That still does not explain one thing.... Why is there hair around my anus?!?!?!
puberty
+blackmesa232323 Wrong guy. I think the guy's name was litojony
There's a bug that lays its eggs around your anus, the chemicals in the eggs cause hair to grow where the eggs were; you should see a doctor.
+blackmesa232323 to prevent chafing of the buttocks, done, next question please
+blackmesa232323 brethren! one of us!
Billy: Today I'm 21! I'm old enough to drink...Legally!
Mom: Silly Billy, you were born on a leap year, that means your only 5 and a quarter years old according to my calendar
Billy: It doesn't work that way ma
Mom: Have fun at kindergarten!
Billy: Ma!
Lmfao
Nice "Pirates of Penzance" reference
HrothgarXII Believe it or not I haven't seen Pirates of Penzance or even heard of it before you commented it
Is it good?
CZcams, All I want to do is watch a video, stop making me update.
Very good! One of the best musicals I have ever seen. A central point of the story involves a guy who is 21, but turns out to have been born on Leap Day, and, as a character says "You're only 5, and a little bit over."
That is mathematically impossible.
when you already know the answer but just watch it cause of hank xD
I knew it was because a year is actually 365.2522 days long, rather than 365, but I didn't know about it's history and the inaccuracy of the Julian calendar.
@@Rozwarty 365.2422
but WHYYY IS THERE HAIR AROUND MY ANUSSSDSSSSSSSS??!?!?!
+litojonny One day your question will be answered, stick with it bro!
Someone stole your question
+Pratyush Srivastava
Think it's more like an ongoing SciShow comment-meme, or... something.
But hey! April 1st is in one month, so who knows! They might just throw that in there.
So that when you pull it your eyelashes will flutter. Somehow it is all connected....
@scishow WILL WE EVER GET AN ANSWER TO THIS QUESTION?
Rules for the Gregorian calendar:
- Add an extra day every 4 years
- Don't add an extra day if the year is divisible by 100
- Add it back if it's divisible by 400
Imagine being born on 29 Feb 1896 and trying to celebrate your birthday on 29 Feb 1904. That's a whole new kind of leap year baby. (This won't happen again until 2096 and 2104.)
The Julian calendar was off by 10 days in 1582 when the Gregorian calendar was introduced. The Julian calendar is now off by 13 days.
We have leap years so every February 29, we can get out our seats and jump around.
+Naveek Darkroom Get out
Oh, god. This makes leap year birthdays a pain to figure out. 😕
I'm in favor of switching over to Stardates as the new calendar.
0:15 Missed a perfect opportunity for Game of Thrones pun
No
+Equivalent TheIncredible Would have been incredibly unfunny.
No.
Yea
This video is so informative. I’ve learnt a lot of new things today.
My kid just turned 1 today 4 years ago.
im 4 now yeah
+brown lucien
My son won't be able to drive till he is 64, as old as you!
I'm 6 today! 😊 Always loved my birthday for this reason!
+ShayPeee I'm 5 today 😁
wait wut
I always wanted to know this. Thanks!
1:10
"The earth orbits the sun every 365.2425 rotations"
That number is actually 365.2422 rotations.
shut up
JoshLikeCrazy k
OMG what a difference
+Chromework nice meme
+C. Leigh I would would have died
Hey SciShow! Love you guys ! I'm a big fan and I have to ask if you guys have ever made mind/conscious videos? It would be great to have some elaboration on topics like that. Also, I've always been curious about how/why humans can hear our own
thoughts.
Most comprehensive explanation for a leap year I've ever heard, thanks guys
Happy 5th monday in feb. Yay.
Leap seconds > leap years
Mind = Blown
Given that leap years add a day and leap seconds add a second, I would argue that leap years are greater than leap seconds based on the fact that days are bigger than seconds.
I'm saying that leap seconds are better than leap years.
+Poop Poop Leap smears though
Thank you!
Whenever there's a leap year, I can only think of the paradox song from Pirates of Penzance. "Though counting in the usual way, years twenty-one I've been alive. Yet reckoning by my natal day, yet reckoning by my natal day...I AM A LITTLE BOY OF FIVE!"
0:47 I think it is important to note that the 'days' referred to in this entire video are mean solar days (the average time it takes for the sun to reach the same position in the sky), while this definition is actually that of sidereal days, a very slightly shorter amount of time. Long enough, however, that there is (exactly) one more sidereal days in the year than solar days.
I know that this comment is from 8 whole years ago, but for folks who want to know why this is, it is accounting for the fact that if the Earth wasn’t rotating around its axis at all, there would be one “day” every time it went around the sun.
Nice attention to detail, making the Earth's orbit slightly elliptical and slightly off-centre. The whole SciShow and SciShow Space team is fantastic!
Is there some adults who actually don't know this?
+Dominic Bruce
1) *are
2) remember how an average is dumb and then remember that half of all people are dumber than that.
+NewName *facepalm
+Dominic Bruce Are*
+Dominic Bruce I'm pretty sure most didn't know about the extra day every ~7,700 years.
+Dominic Bruce
Not all countries have proper education, I would've though that some adults can come to that conclusion by themselves, even the condescending ones.
ugh FINALLY got to know what happens with that 0,05 day a year. thank you
cgp grey did a really good video on leap years
Thanks 😍
This season has an extra episode!!
You are very fast in delivery but good info! Thank you for sharing the content!
I finally figured it out. SciShow is short for SCIENCE Show!
Mission for attention:Failed.*FACEPALM*
Mercury {Leader Of SD} || MercTFX :(
thats a good video lots of information
A year is a full rotation of the earth's axis, not the earth around the sun.
Common misconception that Scishow should have caught.
David Arias That's the earths rotation about itself not the rotation of the earth's axis.
en.wikipedia.org/wiki/Tropical_year
Happy leap year everyone
You should mention leap seconds! They help correct minor irregularities in orbits.
wow, thanks!
So that our calendars don't get out of sync with the seasons. As simple as that.
I have a question but it's not related to this video. Is it possible for an object to travel at light speed jut by free falling? Because there are gravitational field strength that can pull in light(black hole) so it that possible? Hope that you guys can make a video of it or maybe just reply me thx!
Next year, 2020, is a leap year, too! My cousin was born on February 29th. Imagine having a “real” birthday only every four years.
Wow! Both Brainy5s And SciShow created a video on the same topic and released it on the same day! Crazy
Merry leap day!
A day is not exactly one rotation, there's one more rotation per year than the number of days.
Also, the Julian calendar is currently 13 days behind.
My bad. I wish I could have seen this a few days early. I was convinced my sister, a Leap Year baby, was only 13 because I thought we skipped 2000. I remembered something about a 400 year rule, but I remembered wrong. At least now I know. Thanks for these educational vids!
But why do we call it a LEAP day? It sounds like we are skipping a day by leaping over it.
+YoungTheFish Eh, yeah that's a good question. Reminds me of the "Schaltjahr" in german, literally meaning "switch-year" what doesn't make any sense to me either. :D
Because the date will jump "leap over" a day every 4 years.
A date falls on Monday in 2015, falls on Wednesday in 2016.
Jordan Martirossian Well, THAT does make sense. Wikipedia? :D
Jordan Martirossian Yes. Everyone’s on the right track. But if a date is between January and February, the weekday would skip in the following year. For instance, New Year’s was on a Friday in 2016, but Sunday in 2017.
Pretty amazing that they managed to get the "year" this accurate back in 1582!
The Babylonians, Olmecs, Chinese ect did all math for this thousands of years before Renaissance Europe. Greek mathematicians calculated how big the earth was 4000 years ago (and no, people didn't think Columbus was going to fall off the Earth. Shakespeare made that up to add drama to his play.)
He already included this in three other videos... Three, two, or one I forgot.
Small error. at 1:05 Hank says Earth orbits the Sun once every 365.2425 days. It's more like 365.2422 days. That's why the Gregorian calender is still off by one day every 7.700 years. The Gregorian calender would be PERFECT if it was 365.2425 days, because that's exactly what you get from the new leap year rules.
+Paul Visschers Calling it a rotation may be incorrect, but it does not invalidate his reasoning. Contrary to that, if the earth did orbit the sun in 365.2425 days then the whole part of the video about the slight error in the Gregorian calender would not exist.
+Leslie Bevis I'll give you an even smaller error. Our relative speed around the sun is not constant, not even our rotation, it depends on numerous factors from the universe. A star exploding on other side of galaxy can cause the tiniest fraction of change. Knowing this all is dynamic, we just keep the Gregorian Calendar as a default, but keep track of all changes and just add a day when needed, keeping it dynamic like the world is.
+Paul Visschers I've read the distance between sun and earth already changes about 3% during one cycle. However, I do not have the knowledge to what causes these things exactly, I just know the world is dynamic and therefor we keep track of it.
+W Master The earth is on an elliptical course around the sun. So the distance changes with that. Smaller errors get leap seconds, the Gregorian calender is great and the earth rotates around the sun in 365.256 days (according to wikipedia) - what? I'm confused.
0:43 Ehh, the tidal link between the earth and the sun is pretty weak, but it is there.
XD I misread the title as "why we leap years" apparently we play leap frog with the years
Haven't we slightly slowed the rotation of the earth by storing water in reservoirs and keeping it further away from the earths rotational center. That would make the days longer, therefore the years also. Not much longer I know, but it still would add up.
Isaiah 38: 8 and 2 Kings. 20: 1 -11. Tell us about the changing of the Calendar. From 360 to 365 and one quarter days. Bless you.
Could you do a video on oscillation and simple harmonic motion
"the universe doesn't care about our calendars" now that's comforting
happy random extra day everybody!
To the last bit: We care more about the position and timing of things now though. I doubt that people in that future period, if they still use the same calendar, will let that extra day slip by.
Here's the part I never understand, how did people back then know how and why the calendar was off? I get that after a couple centuries you would notice that your seasons are misaligned, but they apparently knew about the issues in advance and just chose not to deal with them. ...but how did they know about them?
Anybody else a leap baby? Happy (REAL) birthday to us!!
my head hurts
Thanks for the weird birthday Gregor
We should all just use a form of unix time, seconds from the beginning of the universe sounds like a good precise and universal constant that can always be checked and compared no matter where you are, much like we define a meter as the time it takes for light, a universal constant, to travel a certain distance in a certain amount of time.
Different measurements from different perspectives. The Earth, as viewed from a point outside of our solar system, would have a rotation that's about 3 minutes 56 seconds less than 24 hours. The average rotation of 24 hours is the Earth's rotation in relation to the Sun. The difference between the Earth's rotation in relation to space and the Earth's rotation in relation to the Sun is about 3 minutes 56 seconds; that is about 1/365.2425 of a year. Why? Because if the Earth did not rotate on its axis at all (in relation to space), then in one solar year there would be 1 day on Earth, so in every year there is 24 hours that is NOT caused by the Earth's rotation (in relation to space).
The Earth actually completes 366.24 rotations every [tropical] year. The length of a solar day is longer than the time it takes to rotate (a sidereal day) because the Earth has to rotate "extra" to account for its movement around the sun. Over a full orbit, that adds up to one extra rotation [approximately].
We're already at another leap year that is 2020 and interestingly the year Hank was born (1980) was also a leap year!
How do reflexes work??? You should do a video!!
Please, where'd you get that shirt? Who makes it? I gotta get a few!
Long story short a solar year is 365 1/4 days so we have 365 days in a year but every 4 years we add up the past 4 1/4ths to make up a whole day which is 29th of Feb..
I invented a complex calendar that only I use and will remain accurate for seriously around 3 million years.I set my Ipad to it.
So basically what it comes down to is that the day and night cycle, the lunar cycle and the cycle of the sun don't EXACTLY line up perfectly causing misrepresentations in calculating time?
By the time we ned to start worrying about calendar drift with the Gregorian calendar we'll be needing to overhaul it anyway because the length of the year is slowly increasing.
+Fakjbf I don't think the length of a year will be that much different in about 100,100 years. But I could be wrong
I wonder how the slight inaccuracy in the Gregorian calendar will intertwine with the fact that with no known regularity, the years are of irregular length (leap seconds).
I'm a fan of ignoring the seasons and basing the calendar on the stars & constellations (those don't change for millions of years). Far better than changes every few thousand years.
nice video
Just so I understand correctly, if the year is divisible by 100 and also by 400 to a "whole" number then it's a leap year, whereas because for example 1900 was divisible by both but not a whole number by 400 then this negates that correct? And any other year divisible by 400 to part or whole number is also a leap year, such as this year (5.04)?
Space travel could need its own calendar eventually. Thanks for explaining why I need to live with October being the tenth month.
That's where stardates in Star Trek come into play.
Pontifex Maximus is an awesome title.
The physics stickyness
Hoppy Leap Day everyone! (2024)
Talk about the recent discovery of Einstein's gravitational waves!
+ETHN They talked about this on SciShow Space :)
+strawberrylemonades Handn't realized they have a 2nd channel, whoops
You state 365.2425 as the number of days in the solar year, but actually it is the number of days in a year in the Gregorian calendar. The astronomical number is closer to 365.2422. I have been told that the Mayans actually had a calendar that was more precise than ours on this point, having 365.2420 days in the year.
So there's a rule, there's an exception to the rule, and there's an exception to the exception to the rule. Great!
I wonder what flat earthers do on this day?
+Ruy Duarte Sit in their man-caves and cry into a pringles can.
+Ruy Duarte
Yell angrily at clouds and curse the government?
+Ruy Duarte
Wear a tin-foil suit to protect themselves from reptilian mind control waves.
Wish you had posted this video a few days earlier. I recommend videos to a high school astronomy teacher. Sometimes she finds one useful as class or supplemental material. This one would have been a good candidate, but since it came out Feb 29, she would not be able to use it till Mar 1, a bit behind the curve.
I was just wondering "Hmmm, I wonder if Hank covered the cause for needing a lea....(looks at subscriptions) Oh, I guess he has!" :)
You're welcome for the Julian calendar, Plebeians!
one extra monday... like the world needs more.
Wow. I am a leap year child. Yay I guess
I prefer the gormanian calandar :P Leap year is just double intermission after all :P
All joking aside it's actually a decent calendar lol
It still doesn't explain why dad hasn't come home yet :(
I have a question about consumption. Is it healthier to drink a cola each day for one month, or drink one month's worth of cola for one day? I know that the healthiest is of course to not drink any. But I'm interested, because I usually go for the last option, I'll take a break from candy and sugar, then just eat a lot of it for a few days and then stop completely for 1-3 months.
+MeNotyouxD Didn't they do an episode on diets and binging already?
Did they? If so can you tell me what it's called, I tried to look around, couldn't seem to find anything.
+MeNotyouxD One of these days you're gonna fuck up your pancreas that way
+MeNotyouxD It's better to drink 1 a day than drink a month's worth in a single day. Your body will be able to easier absorb the cola incrementally than digest it all at once. You will hurt yourself drinking a month's amount in one day.
+MeNotyouxD when you eat sugar your body puts out insulin. your pancreas which makes the insulin has a limited amount. sort of like cumulative effect, once your pancreas has made that limit amount you are totally fucked and will be diabetic.
eating a slice of bread is worse for your pancreas than eating a teaspoon of pure sugar. what you are doing is extremely bad for you.
Why do we have to explain this in 2016!?
Our educational system is a failure.
lohphat Kids are probably wondering why they don’t see February 29th that often. Plus, it’s kind of important for people to know the whole system. Imagine if everyone said it was Feb. 29, but it was actually March 1. Lol.
People should already know this
Would you make a video (animation) about the sun track and velocity in the Galaxy.
Thanks.
It would be nice to explain calendar by Milutin MIlankovic.
Why do we drive on a parkway and park on a driveway?
Have you covered sidereal vs. solar days?
I feel like we get a variation of this video every year lately
not by the same channel, but by affiliated channels
You mean every leap year?
Shelly Bai my mind!
Now the question is what will we do when we have multiple planets with different days to work on.
I thought that at the time the Gregorian calendar was invited, the Julian calendar was 11 and not 13 days off...
+What's Their Name Again? That's right, the current difference is 13 days, not 16.
Wait…I just realized this is John Green's brother. So that's why they sound the same
can you make a video on the differeces between hemp and (because i cannot spell the real name) pot
The problem is, we base our time on OUR frame of reference (the sun).
And a debate out metric vs imperial, metric is better, but still not perfect, because volume/weight is based on water at a specific pressure (1 earth gravity).
So by the time the Gregorian calendar is off by enough to make a difference, humanity will have passed from memory into archaeology and the cockroaches will have come up with their own solution.
Nah we still have to do that for Mar.