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The Leap Year as Explained by Neil deGrasse Tyson | StarTalk


Lee piers no they don’t happen all the

Lee piers no they don’t happen all the time but neither do presidential

time but neither do presidential

time but neither do presidential elections but people don’t freak out

elections but people don’t freak out

elections but people don’t freak out with it well it’s a presidential

with it well it’s a presidential

with it well it’s a presidential election year it’s rare notes every four

election year it’s rare notes every four

election year it’s rare notes every four years chill out we on earth as we orbit

years chill out we on earth as we orbit

years chill out we on earth as we orbit the Sun we know how to calculate a year

the Sun we know how to calculate a year

the Sun we know how to calculate a year is how long it takes to come back to

is how long it takes to come back to

is how long it takes to come back to where you were

where you were

where you were that’s a year but it turns out if you

that’s a year but it turns out if you

that’s a year but it turns out if you cut the number of days we live into the

cut the number of days we live into the

cut the number of days we live into the year it doesn’t divide evenly so there’s

year it doesn’t divide evenly so there’s

year it doesn’t divide evenly so there’s not an even number of days in the time

not an even number of days in the time

not an even number of days in the time it takes earth to go around the Sun it

it takes earth to go around the Sun it

it takes earth to go around the Sun it takes like 365 and a quarter days to go

takes like 365 and a quarter days to go

takes like 365 and a quarter days to go around the Sun so we just ignore that

around the Sun so we just ignore that

around the Sun so we just ignore that quarter day just sweep it under the rug

quarter day just sweep it under the rug

quarter day just sweep it under the rug for three years the fourth year how many

for three years the fourth year how many

for three years the fourth year how many quarters have you added up four quarters

quarters have you added up four quarters

quarters have you added up four quarters so there’s a whole day now that you’ve

so there’s a whole day now that you’ve

so there’s a whole day now that you’ve saved up and in the fourth year you put

saved up and in the fourth year you put

saved up and in the fourth year you put that day back in the calendar and you

that day back in the calendar and you

that day back in the calendar and you give it to the neediest month February

give it to the neediest month February

give it to the neediest month February and so this is the origin of the leap

and so this is the origin of the leap

and so this is the origin of the leap day and this is as it was conceived in

day and this is as it was conceived in

day and this is as it was conceived in the Julian calendar the calendar that

the Julian calendar the calendar that

the Julian calendar the calendar that preceded the current calendar the

preceded the current calendar the

preceded the current calendar the Gregorian calendar most people don’t

Gregorian calendar most people don’t

Gregorian calendar most people don’t know that this one every four year rule

know that this one every four year rule

know that this one every four year rule over corrects the leap day it’s not

over corrects the leap day it’s not

over corrects the leap day it’s not actually 365 and a quarter day it’s a

actually 365 and a quarter day it’s a

actually 365 and a quarter day it’s a little bit less than a quarter so you

little bit less than a quarter so you

little bit less than a quarter so you wait four years and put in a whole day

wait four years and put in a whole day

wait four years and put in a whole day you put in too much so you have to wait

you put in too much so you have to wait

you put in too much so you have to wait until you put in a whole day too much

until you put in a whole day too much

until you put in a whole day too much then you take out a leap day that would

then you take out a leap day that would

then you take out a leap day that would have otherwise appeared so every hundred

have otherwise appeared so every hundred

have otherwise appeared so every hundred years you have over corrected by a leap

years you have over corrected by a leap

years you have over corrected by a leap day by an entire day so every hundred

day by an entire day so every hundred

day by an entire day so every hundred years 100 years are divisible by four

years 100 years are divisible by four

years 100 years are divisible by four aren’t they

aren’t they

aren’t they every hundred years you take out the

every hundred years you take out the

every hundred years you take out the leap day that would have otherwise been

leap day that would have otherwise been

leap day that would have otherwise been there so 1900 was not a leap year 1800

there so 1900 was not a leap year 1800

there so 1900 was not a leap year 1800 was not a leap year 1700 was not a leap

was not a leap year 1700 was not a leap

was not a leap year 1700 was not a leap year for this reason okay so now by

year for this reason okay so now by

year for this reason okay so now by taking out that day now you have over

taking out that day now you have over

taking out that day now you have over corrected in the opposite direction

corrected in the opposite direction

corrected in the opposite direction and now there’s a day that you have to

and now there’s a day that you have to

and now there’s a day that you have to put back in it turns out every 400 years

put back in it turns out every 400 years

put back in it turns out every 400 years so every 400 years in the century year

so every 400 years in the century year

so every 400 years in the century year that would have not had a leap day on

that would have not had a leap day on

that would have not had a leap day on the century rule gets a leap day put

the century rule gets a leap day put

the century rule gets a leap day put back in on the 400 year rule this sounds

back in on the 400 year rule this sounds

back in on the 400 year rule this sounds complicated but it has profound

complicated but it has profound

complicated but it has profound implications in the year 2000 it’s a

implications in the year 2000 it’s a

implications in the year 2000 it’s a century year that wouldn’t normally get

century year that wouldn’t normally get

century year that wouldn’t normally get a leap day but it’s a century year

a leap day but it’s a century year

a leap day but it’s a century year divisible by 400 so you put the leap day

divisible by 400 so you put the leap day

divisible by 400 so you put the leap day back in so when everyone experienced the

back in so when everyone experienced the

back in so when everyone experienced the leap day in the year 2000 they’re saying

leap day in the year 2000 they’re saying

leap day in the year 2000 they’re saying to themself of course it’s a leap year

to themself of course it’s a leap year

to themself of course it’s a leap year it’s divisible by four it’s like no it’s

it’s divisible by four it’s like no it’s

it’s divisible by four it’s like no it’s a leap year because it’s a century year

a leap year because it’s a century year

a leap year because it’s a century year divisible by 400 they’re in is through

divisible by 400 they’re in is through

divisible by 400 they’re in is through gorian calendar as it was established in

gorian calendar as it was established in

gorian calendar as it was established in 1582 that’s the story of the calendar

1582 that’s the story of the calendar

1582 that’s the story of the calendar you asked okay I was sitting here

you asked okay I was sitting here

you asked okay I was sitting here minding my own business and you had to

minding my own business and you had to

minding my own business and you had to ask about the calendar and the leap day

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