How Earth Moves

It’s here! Science stuff, mind-blowing stuff, Vsauce stuff, oh my!! THE CURIOSITY BOX: https://www.thecuriositybox.com/

Jake’s video about The Curiosity Box: https://www.youtube.com/watch?v=p91-G...

Minute Physics on why December days are the longest: https://www.youtube.com/watch?v=nZMMu...

StandUpMaths on calendars and leap days: https://www.youtube.com/watch?v=qkt_w...

Tom Scott on the Equation of Time: https://www.youtube.com/watch?v=d9Qno...

My video on what would happen if the Earth stopped spinning: https://www.youtube.com/watch?v=K0-Gx...

GREAT visuals showing how Earth moves around the sun: https://www.youtube.com/watch?v=82p-D...

http://www.timeanddate.com/

George Washington’s birthday: https://www.archives.gov/legislative/...

real-time sub solar point location: http://rl.se/sub-solar-point

Lahaina noon images from the Oahu Astrophotography club: https://www.facebook.com/OahuAstropho...

analemma: https://en.wikipedia.org/wiki/Analemma

great solargraph and analemma images: http://analemma.pl/english-version

interactive seasons and ecliptic simulator: http://astro.unl.edu/classaction/anim...

Nasa video of seasonal movement of Earth: https://svs.gsfc.nasa.gov/20063

Tropical year: https://en.wikipedia.org/wiki/Tropica...

Earth rotation specifics: https://svs.gsfc.nasa.gov/cgi-bin/det...

How Earth moves through the universe:

https://astrosociety.org/edu/publicat...
http://www.slate.com/blogs/bad_astron...
http://space.gizmodo.com/racing-while...
https://www.reddit.com/r/askscience/c...

minute physics on cab: https://www.youtube.com/watch?v=_mZQ-...

PBS spacetime on the cosmic microwave background:

https://www.youtube.com/watch?v=3tCMd...

https://www.youtube.com/watch?v=wcBji...

CMB rest frame:

http://physics.stackexchange.com/ques...
https://www.reddit.com/r/AskPhysics/c...

Wikipedia:

https://en.wikipedia.org/wiki/Day
https://en.wikipedia.org/wiki/Solar_time
https://en.wikipedia.org/wiki/Siderea...
https://en.wikipedia.org/wiki/Calendar
https://en.wikipedia.org/wiki/Gregori...
https://en.wikipedia.org/wiki/Calenda...
https://en.wikipedia.org/wiki/Day_len...
https://en.wikipedia.org/wiki/Cosmic_...

wikicommons images:

https://en.wikipedia.org/wiki/Sundial...
https://en.wikipedia.org/wiki/File:Ca...
https://en.wikipedia.org/wiki/Miami_B...

To explore space, I highly recommend these:

http://www.shatters.net/celestia/
http://en.spaceengine.org/

music by http://www.youtube.com/jakechudnow
and http://www.audionetwork.com

Awesome 3D graphics by Eric Langlay: https://www.youtube.com/user/ericdrav...
Lame 2D stuff by me.

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Closed Caption:

yeah
hey Vsauce Michael here
do you have a best friend who is there
for you 24 7 365
sorry that's not really good enough if
your friend truly had your back
they would be there for you 24 . 000000
6 7 365 . 242 1891 also george
washington was born on februari 22nd
1732
at least that's what we're told
however his family bible says he was
born on februari 1117 31 / -
so which is it mr. I cannot tell a lie
oh and don't even ask about 1750 - in
Russia 1752 looked pretty normal but
check out what the British Empire was up
to that year
nothing really out of the ordinary
except ember
the second was followed by the 14 were
11 days just deleted where they go what
happened then it is time to question
time
and how the earth moves reconciling both
of these things has led to some pretty
strange things we all love time-lapse
videos of the stars moving across the
sky but really we are the ones who are
moving tumbling through the universe on
a giant wet Rock vehicle called Earth
with a windshield called the sky as
viewed from above the North Pole
we spin counterclockwise West chases
east
I always remember this by thinking of
the US as a weird main headed animal
with Texas and Florida lakes running
forward but we don't just spit
we also revolve around the Sun on a
plane tilted 23.4 degrees
native to our spin its kind of
nauseating at this scale
but from this perspective you can see
that the Sun rising and setting is just
the earth pointing you towards and then
away from the Sun
this motion causes your sunrise your
noon the moment when the Sun is highest
in your sky before your sunset to more
closely investigate this movement
let's talk about meridians you are on
one at this very moment your meridian is
just a line from where you are right now
straight towards the North and South
Poles it's a line of longitude as
opposed to the horizontal lines that lay
flat when north or south is up that we
call latitude or actually latitude
the Sun is highest in the sky to you
your noon when you're meridian is
pointed right at the Sun a cool thing
happens at this moment all shadows
around you . directly towards one of
Earth's poles
unless you're on the sub solar . the
subsolar point is the point on earth
surface directly below the Sun it's
always somewhere you can check its
current location online links as always
in the description
on the subsolar point shadows fall
straight down so they can easily
disappear
twice a year the subsolar point crosses
over Hawaii the only place in the US
where it hits land and when it does it
is called lahaina new meaning
cool son
straight vertical objects look unnatural
during this brief time like they don't
belong as if they were photoshopped in
without regard for reality in Honolulu a
sculpture by isamu noguchi called sky
date
cast a twisted shadow all day every day
except during lahaina knew when its
shadow is a perfect circle
you may not live in a place where the
Sun never appears directly overhead but
once every earth rotation the subsolar
point falls somewhere on your meridian
making it noon for you
the technical name for this noon for you
is local apparent solar noon
the clock on your wrist and be clock on
your phone
don't tell you your local apparent solar
time because long ago we realized that
if every Meridian had its own time a
person just a few kilometers away seeing
different shadows than you did would
disagree with you on what time it was so
towns adopted their own time and later
on this trick was standardized and time
zones as we know them today came about
but that's not all we didn't like about
shadow based sundial time to explore
deeper we have to begin by asking what's
a day
I mean obviously it's just the time it
takes the earth to turn around once
right
but according to what everything else in
space is moving in some way to the
universe doesn't include a convenient
sheet of graph paper at absolute rest we
can trace paths on the best we can do on
that front is to look at very very far
far far away stars so far away like
distant features of the landscape out
the window of a moving car
they barely move as earth does now to
them a meridian on earth completes a
trip around about once every twenty
three point nine hours
this is called a site . day side Irial
means pertaining to the stars
even though the side Irial day seems
pretty clear it's not what our calendars
and clocks are based on because there's
a mirror star whose position relative to
us has a bigger effect on our lives
the Sun
looking down on the North Pole at
Earth's counterclockwise spin the earth
also moves counterclockwise around the
Sun after a side Irial day the earth has
moved a bit along its orbit so some more
rotation is required for the same
meridian too . back towards the Sun
again this longer definition of one
rotation is what the modern calendar and
clock is based on it is called the solar
day but here's the thing
exactly how long the earth has to rotate
to complete a solar de changes day today
our clocks are just based on the average
amount of time this takes
so throughout the year they fall ahead
and behind the Sun this is a solar graph
a picture of the sun's path across the
sky every single day
if our clocks actually told us local
apparent solar time if you took a
picture of the sky every day at noon
you should get a line of sons but this
is what really happens over the course
of a year it will appear as though your
clock is running slow and then fast and
then slow again and fast again
this problem was known since at least
ancient times even if it's cause was it
in order to reconcile the two the
equation of time was constructed in this
sense equation means to reconcile the
equation of time was applied to one
o'clock said in order to compute the
real time the solar time a sundial would
show you some fancy clocks called
equation clocks were made that would do
this for you but eventually we gave up
we gave up and just said no the real
time isn't what the Sun says it's what
our inventions say now this transition
was a big one
it was humanity growing up it was like
the first time you realize you're
stronger than your parents we realized
our time pieces were more regular
and turned our backs on the timepieces
nature had but what causes this
disagreement in the first place
as it turns out the answer revolves
around revolving the way the Earth
revolves around the Sun if the equator
face to the Sun all the time and the
earth always orbited at the same speed
the subsolar point would just stay right
there on the equator throughout the year
and the amount of extra time spent
rotate the earth needed to do to finish
a solar day would always be the same but
those two things aren't the case
first of all the Earth's orbit is
slightly elliptical so its speed varies
throughout the year when it's moving
around the Sun faster around the
beginning of january the amount of extra
turning time needed to complete the
solar day is longer than when it's
further away from the Sun and moving
more slowly
there's more because the earth is tilted
the subsolar point is dragged through
out the year in a circle around Earth
that's not be equator so it changes
direction moving northeast then leveling
out and going southeast before leveling
out and going northeast again during
times of the year when the subsolar
point is being dragged by Earth's orbit
mostly East it gains against Earth's
spin faster more time is required for
the day to finish now
by coincidence we are alive at a time
when both of these phenomena
lengthen and shorten days at roughly the
same time so they add up making sep
tember 18 almost a minute
shorter than the longest day of the year
december twenty second for northern
hemisphere Ian's December has the
shortest periods of daylight but the
whole solar day
from sunrise to sunrise is for everyone
on earth the longest of the year on
december twenty second people in the
North just spend most of it in darkness
earth's tilt it doesn't just affect how
long a day is it also affects how long a
year is this is because the earth's tilt
is what causes the seasons for the half
of the earth
tilted towards the Sun the same amount
of solar radiation is spread across less
space than it is on the other half
so there's more heat energy laid down
for area
this causes what we call summer and
winter for the other half the amount of
time from one of these seasonal
orientations of the earth to its
occurrence again is called a solar year
or a tropical year
it's a very useful way to find a year
because it contains every single season
exactly since it's based on the very
orientations that caused them but the
problem is this the number of solar days
that occur in a solar year is not a
whole number
it's almost three hundred and sixty-five
but after that many solar days about a
quarter of a day more happens before the
solar year starts again
this makes designing a calendar more
like designing a call'n her if your
calendar only ever has 365 days in a
year over time those dates will drift
from the seasonal positions they used to
occur there unless this extra quarter of
a turn
adds up to a full day after four years
see march first is coming a day too soon
now
so if we just delay march by adding an
extra day at the end of februari every
four years
a leap day we're back on track
weekdays do not add days to your life
you're still going to live the same
number of them they just change what we
call them but really who cares about
being one day earlier every four years
I mean one day isn't much you've hardly
noticed it but over time
well if America's Founders had declared
not only independence from britain but
also from leap days and abolish them
from happening today two hundred and
forty years later their calendar would
be a full two months ahead of Earth's
position putting America's coldest
winter days in april and its hottest
summer days in october
adding a day every four years is what
the famous julian calendar does
introduced in 46 BC by Julius Caesar
it was feeding facto standardized
western calendar for a very long time
more than a millennium but it's not
perfect
look closely leap days actually move the
calendar just slightly too far
each time because I lied 365 and a
quarter solar days
don't occur within one solar year the
real number is slightly less and
fluctuates year to year based on
long-term changes to earth and the sun's
movements which means adding one day
every 40 years is just ate see too many
by 1582 julian calendar dates were ten
days behind the seasons compared to
where they used to be
that's not bad 10 days and more than a
millennium and a half but the Catholic
Church cared because they wanted easter
to occur exactly when it used two
centuries ago astronomers of time
realized that if leap days
push the calendar too far behind the
seasons we would just need to celebrate
fewer of them to fix the problem
specifically we would need three fewer
leap days every for centuries
the rule they wrote to achieve this
stated that every four years would
continue to be a leap year except if it
was divisible by 100
unless it was also evenly divisible by
400
this removes three every 400 years on
October fourth
Pope Gregory the 13 introduced this new
calendar
it took his name the gregorian calendar
he also undid the drift that had
occurred since the early days of the
julian and declared on October fourth
that tomorrow would be october 15
october fifth to the 14th never happened
in 1582 in countries that
listen to the Pope it took the rest of
the world centuries to hop on board
England and its colonies like the soon
to be united states of america adopted
the gregorian in September of 1752 by
which point there Julian dates were off
from the seasons by 11 days hence the
disappearing up the third through 13
when adopted the first of the year was
also moved from march to january first
this explains why George Washington's
Birthday has two answers
although more closely hitched to the
seasons than the Julian the gregorian
calendar still isn't perfect it's
difference causes dates to become one
day off from the seasons every 3216
years other calendars have been proposed
like the one stand up maps calculated
that drips off even more slowly
this video is a great watch by the way
but enough of all of this
let's sit back and enjoy Earth's
movement without trying to divide it up
and named as a caveat keep in mind that
Earth's oceans and liquid inside and
other celestial bodies are always
pulling and tugging and sloshing around
minutely changing Earth's movements
their effect is measurable but difficult
to notice it big scales and also don't
look like much in the short term short
like the length of the human life
looking from above the north of the
Equator spins counterclockwise at about
16 17 km/h relative to the Sun Earth
orbits counterclockwise at 108 thousand
kilometers per hour along a path tilted
23.4 degrees to spin within our local
neighborhood of stars our entire solar
system is drifting 70,000 kilometers per
hour roughly in the direction of the
bright star Vega in the constellation of
Lyra and our solar system is part of a
giant galaxy called the Milky Way on a
plane tilted about 60 degrees
approx like the windshield of the car
looking from above Earth's North Pole
our entire solar system races clockwise
around the galactic center at about
seven hundred and ninety two thousand
kilometers per hour
our whole galaxy is also moving through
the universe we know this because when
the universe was very young
it was so hot electrons and protons
jumped around and photons of light
scattered constantly they couldn't
travel very far before scattering again
so the universe was opaque but then
around 380,000 years after the Big Bang
the universe cooled just enough for
electrons and protons to form hydrogen
sudden
abrupt photons decoupled from this
obstacle course and could travel
relatively unencumbered the universe
became transparent to light since that
moment those early photons have been
propagating through space every day
ancient photons that last scattered off
this
opaque fog at the moment of decoupling a
light Dave further from were currently
is reach us
they are part of the cosmic microwave
background radiation
it is visible in every direction
microwave because although they used to
be more energetic the universe's
expansion is redshifted now some parts
of this radiation are more redshifted
than others because of our own movement
through the universe controlling for the
movements we've already talked about
relative to this infinite cooling baby
picture of the universe
the first and oldest detectable light we
are headed riding along in the Milky Way
in the direction that the constellations
of Leo and Burgo are to us at a speed of
2.1 million kilometers per hour towards
a thing we don't fully understand yet
simply called the Great Attractor
this is how you on Earth's surface are
moving through the universe aboard
Spaceship Earth
ok
now
stop
this is roughly 100 years of Earth's
movement in space
this path we trace from where we began
here is the path you will take through
the universe in your lifetime you didn't
buy a ticket for this ride
your parents signed you up without
asking but nonetheless it is quite
literally the ride of your life
and as always thanks for watching
it is now time for a major Vsauce
announcement
you know how for the last couple of
years we've released a holiday box
well introducing the curiosity box by
Vsauce we created this thing as a
quarterly box
this comes to you four times a year and
it comes packed with amazing exclusive
Vsauce merchandise and incredible geeky
toys picked by myself
Kevin and Jake Plus as always a portion
of the proceeds from this box goes to
funding Alzheimer's research you can get
your own by subscribing at the curiosity
box.com I'm incredibly proud of this
go check it out and as always thanks for
watching
yeah