Hey, Vsauce, Michael here
And here, I am the real Michael
This Michael was created by a brilliant young man named Mitchell,
who brought it to me at a meet-and-greet after Brain Candy Live
It is phenomenal and obviously the most handsome jack-in-the-box ever
Ever-est is a mountain that's 8.848 km tall
Its size is impressive
Or is it?
(Characteristic music of Vsauce, get prepared to be mind = blown)
Let's cut Earth, the entire planet, right in half,
straight through Everest, and then start zooming out
As you can see, Everest's monumentality quickly disappears against Earth's planetary ginormosity
Compared to Earth's diameter
Everest—in fact, all of Earth's ruggedness—barely registers
That can seem surprising, since we are often surrounded by diagrams and maps and globes
that exaggerate Earth's topography
There is a good reason to do that,
but it leads to a misconception about just how smooth Earth is
Here's a typical example:
a cross section of the United States that I found on reddit
The vertical axis spans about 10,000 ft,
but the horizontal axis represents nearly 14 million ft
Stretched to the same scale so as to mirror reality,
the actual smoothness of the Earth becomes apparent
On this 1 ft diameter globe,
Everest is a bump about 2 mm high
Feels good!
But if the Earth was actually this small,
Everest would be a bump only 0.2 mm high
It's 10 times taller than it should be
Only 24 people have seen the Earth, with their own eyes, as a circle small enough to be looked right at;
not as the whole world, but as a little thing suspended alone in space
The further away you are from a ball, the more of its surface you can see
We don't always notice this,
because in our day-to-day lives,
most of the balls we deal with are so small
they're almost always many of their own radii away from us,
and the available amount of their surface visible is near a maximum
Or, they're so big, like the Earth, that we rarely get far enough away fast enough to notice this property
But the next time you are near a ball, get close to it
You'll see that as you get nearer, more of its surface disappears behind the horizon,
but moving back up will make it available again
For most of us, stuck our whole lives on Earth's surface,
such an experience is impossible
WIth nothing around to block your view,
5 km (about 3 mi) is about the furthest you can see
Haze can limit your view and atmospheric refraction can slightly extend it,
but for the most part, everything you can see happens within an area of just 80 km^2
That's not bad, but it's tiny compared with what there is to see
The higher up you go, of course, the further away you will be able to see
That's why it's great to be a satellite
Here's the International Space Station
Yeah, look at that nice bit portion of the surface in view
Unfortunately, this isn't to scale
If the Earth were the size of an apple,
how far away would the International Space Station orbit?
Like this far away?
Maybe this far away
Actually, it orbits… here,
2.7 mm above the surface
That's how far the stem of this apple sticks up
It's not very far
Oh, here's another fun little to scale fact:
if the Earth were the size of an apple, your eyeball would be about the size of the moon
We often imagine that from the International Space Station,
astronauts see the Earth like this, but they're just not that far away
From where they actually orbit,
International Space Station residents only see about 3% of Earth's surface at any one time
And that 3% is too wide to all fit within a window
When I was in Pittsburgh, their science museum had a mock-up of part of the ISS
And as you can see, out of the window, Earth is still quite expansive
Using special lenses, images can be taken from the ISS that look like circular disk Earths,
but the lens is distorting things here
It's fitting much more into the picture
In order to truly witness Earth's entire shape with your own eyes,
you would need to either smash your face right up against the window
or just be floating outside the station
And even then, you would have to move your head to see from edge to edge
So, how high up do you have to go to see the edges of Earth all at once?
And, even if you did that, how much would you actually see?
How much is there to see?
Earth is made of stuff,
lots of stuff: water and dirt and rocks and air, all of which are composed of atoms
tiny things so teeny that a single drop of water contains not a million atoms,
not a billion atoms, or a trillion, or a quadrillion, or a quintillion but 5 sextillion atoms
Earth is made of even more stuff:
not a septillion atoms, not an octillion, nonillion,
decillion, undecillion, duodecillion, tredecillion,
not even a quattuordecillion but 100 quindecillion atoms
But since we live only on the surface of our planet, we unfortunately can't see most of those atoms
If the Earth was shaped like a disk or an icosahedron,
or, say, a cube, or a rectangular prism, or two stellated rhombic dodecahedrons,
we could see more of the Earth than we normally can
But as things are, we actually see nearly the least of Earth's matter possible
because of all solids, a sphere, which the Earth approximately is,
has the smallest surface-area-to-volume ratio—the most stuff inside and the least stuff outside
So, how many of these 10^50 atoms that make up Earth are on the surface for us to see?
That's not an easy question
For one thing, technically, atoms on the surfaces of opaque things like rocks and dirt
aren't the only parts involved in their appearances
Sub-surface scattering can and does happen
Regardless, attempting even a rough approximation is illuminating
I asked Grant from the YouTube channel 3Blue1Brown for some help
And he pointed out that if you calculate the number of circles with atom-sized radii
that could, packed optimally, cover a sphere with the surface area of Earth, you'll get about 1.5×10^34
That's a lot of atoms
But then he pointed out that the Earth's surface isn't smooth
Its roughness provides extra surface area for atoms to occupy
Without a complete description of the shape of Earth's surface—every mountain and valley,
every bump on every rock—this is just gonna be hopeless, right?
Well, here's the thing, Earth is made of little rugged shapes that from far away make big rugged shapes
In other words, Earth's surface can be described as a fractal
There is a regularity to its roughness
In fact, mathematicians have even assigned a fractal dimension to Earth's surface: 2.3
To see what that means, I highly recommend Grant's video on fractal dimensions
It's fascinating
Using 2.3 and assuming that it applies from the scale of a human hair up to that of a mountain,
Grant found that the number of atoms on Earth's surface changes significantly:
up from a power of 34 to a power of 37
That's 1000 times more atoms
So, maybe we shouldn't count Earth's roughness out just yet
It's smooth, but not perfectly
To put that number in perspective, the human body contains about 10^27 atoms
That's 10 powers of 10 less than the surface of the Earth
10 powers of 10 is 10 billion
There are about 7.5 billion humans
So, more or less, it can be said that there are the same number of atoms in every human body right now
as there are on the surface of the Earth
As I've shown before, all human bodies piled into one place would barely even fill the Grand Canyon,
but all human atoms spread across the Earth would almost perfectly cover it just one atom deep
Fun fact: the mass of the atmosphere is about 2.5% less
than what you would get by multiplying sea level pressure (14.7 psi) by the surface area of the Earth
because Earth's terrain displaces about that much air
Huh, Earth's surface is pretty cool
Obviously, I mean it got lichen and monster trucks
and an island in a lake on an island in a lake on an island
But from down here, on its surface, we just can't see that much of it
Your view of Earth is obstructed by lots of opaque things: walls, buildings, trees, rocks, terrain
If Earth was flat, you could see further, but sorry, it's a rough world out there
Or is it?
If you could hold the Earth in your hands like this, how bumpy would it actually feel?
We already saw that even our planet's biggest bumps barely register relative to Earth's size
But let's go somewhere famously flat,
where relative to our size, terrain rarely gets in the way of seeing lots of the planet:
the US state of Kansas
I grew up here and took this footage while driving across the state last year
You can probably see why Kansas is often called "flatter than a pancake"
However, although it is famously flat, Kansas is not the flattest US state
In a fantastic piece of research, Jerome Dobson and Joshua Campbell defined "looks flat" like this:
if, from a given point, any part of the terrain within the horizon rises more than 0.32° up
(about the height of a 30 m hill at the horizon),
a typical person would say, "Hey! That part's not flat!"
By cleverly applying this rule to topographical data, they were able to give every state a flatness score
West Virginia was the least flat
Kansas was only the seventh flattest
Delaware, Minnesota, Louisiana, North Dakota and Illinois are all, by this method, flatter than Kansas
As was the number 1 flattest state: Florida
Adam Savage and I had the pleasure of visiting Florida with our Brain Candy Live show this year,
and as this footage from atop the King Center in Melbourne, Florida shows, it's pretty gosh dang flat
Even though Kansas is not the flattest,
it is the state most often ranked flattest when the general population is asked
It is truly, scientifically flatter than a pancake—it's been demonstrated
But there's more to the story than that
In 2003, researchers took a 130 mm wide pancake procured from IHOP and analysed its local reliefs
They found the difference between high and low points was on the order of about 2 mm
If a typical pancake like this was the size of Kansas, 5 million times larger,
2 mm high peaks would be 10 km high mountains
In comparison, Mount Everest is only about 8.8 km tall
and Earth's deepest scar, the Marianas Trench, is thought to be just under 11 km deep
So, not only is Kansas about as smooth as a pancake, but so is every other state in the union
and so is the entire world
If you were a giant holding the planet in your hands like this,
you and it would be torn apart by the immense tidal forces created by your gravities
If somehow you could avoid that though,
the planet would feel not much rougher than running your hands over a pancake
But a soggy one, right?
I mean, most of Earth's surface is covered in water—your hands would get wet
Or would they?
Yes, Earth is covered in liquid, but the depth of that liquid, like the mountains above,
just doesn't compare to the total size of the planet
As it turns out, if the Earth was the size of a typical classroom globe like this one, 1 ft in diameter,
the volume of water contained in, above and on it would only be about 14 mL
That's this much water
It's kinda hard to believe because at this scale, spreading this much water across all of the ocean surfaces
would be pretty much impossible due to surface tension
But, this is it:
all of Earth's water compared to all of Earth
90% of the space on our planet life can live in is in here
The other 10% is dry land
So, no, you wouldn't get wrinkly fingers playing with an Earth like this
You could sop it dry just with a paper towel
Despite the incredible area oceans cover on our planet,
their depth is just nothing compared to the size of our entire planet
You may have heard it said that if the entire planet were shrunk down to the size of a billiard ball,
it would be smoother than a billiard ball
After all we've seen so far, that seems believable, but as it turns out, it's not true
The misconception stems from the interpretation of the World Pool-Billiard Association's rules
According to them, a ball must have a diameter of 2.25 in ± 0.005 in
Some writers have taken this to mean that pits and bumps of 0.005 in are allowed
Proportionately, on Earth, that would mean a mountain that was 28 km high
So, since Earth has none of those, Earth must be smoother than a billiard ball
Except if bumps that high were actually allowed on a pool ball,
a ball covered with 120 grit sandpaper would be within regulation
Clearly, the 0.005 in rule is more about roundness, deviation from a sphere, and not texture
In fact, as microscopic photography has shown, imperfections on regulation balls are only 1/100,000 in,
or about 0.5 μm deep and high
Scaled to the size of a billiard ball, Earth's Marianas Trench would be 49 μm deep
So, Earth is smoother than a pancake but not smoother than a billiard ball
Nor, as xkcd wonderfully showed, is Earth smoother than a bowling ball
But hold on, earlier we were using the word "flat", now we were using the word "smooth"
That distinction is important
You see, the Earth isn't flat like a plane (or is it?)
Instead, it curves
It's a ball
Pieces of Earth, like Kansas, might be quite smooth, but they curve along with Earth
If you were to stand in the middle of Kansas,
people on the eastern or western edges of the state would appear to be, not level with you,
but about 8.1 km below you
That's nearly the height of Everest
And if they stood straight up, they'd be tilted nearly 2° relative to where you thought up was
Here is an interesting coincidence:
generally speaking, 1 mi from where you are, Earth curves down about 8 in;
1 km from where you stand, it curves down about 8 cm
The rate of drop due to curvature isn't a linear one
You can't just multiply any distance by 8 to get the drop due to curvature
Instead, use an online calculator like the one I have linked down in this video's description
You can put in any distance you want
Anyway, the visibility limit caused by Earth's curvature is your horizon
It encircles you like a visual cage,
but it's a cage whose radius is determined by how high up your eyes are
Conan O'Brien, at 6 ft 4 in tall, can see up to 5 km in any direction,
but Snooki, at 4 ft 8 in, can only see about 4.3 km
To find out how far away your horizon is,
geometrically, just use the online tools I've put down in the description below
Earth's texture can get in the way of your horizon but can also cause things beyond the horizon to peek into view
HeyWhatsThat.com factors all of this in
If Earth was a smooth sphere, the view from atop Ben Nevis, the highest mountain in the British Isles,
would end at the horizon 131 km away (about 80 mi)
Such an area would look like this
But factoring in Earth's ups and downs, here's a more precise boundary of what you can see
Loch Treig, Scottish Gaelic for "lake of death", is only about 10 mi from the peak
That's within an 80 mi radius, but it can't be seen because terrain in the way blocks it
Parts of the Atlantic Ocean and the North Sea 8 times further away can be seen
They lie at the limit of the Earth's curvature, just before it bends the surface out of sight
These spikes extending beyond the geometric horizon
are caused by things beyond it that are tall enough to peek above Earth's curvature
In the case of Ben Nevis, this includes high elevation parts of Northern Ireland
OK, enough about the surface and what it's like close up, let's go further away and see more
This'll be fun, but there'll be a trade-off
The further away you are from something, the smaller it will appear to be
Moving away from Earth will make more area available to see, but that area will take up less of your field of view
It can be difficult to illustrate this in a YouTube video,
because your field of view, the shape and size of what you can see with you head still,
just by moving your eyes around, is about 120° up and down and more than 180° horizontal
A screen is just a window of that space—nowhere close to filling it, unless you get uncomfortably close
To help us visualize large apparent sizes, let's replace the spherical Earth with a flat disk
that's always the same distance from the observer
This disk can be given an apparent size equal to Earth's from any altitude,
and the disk can contain on it everything that would fit within your horizons from any altitude
OK, so, standing on the surface looking straight down, Earth will take up nearly a full 180° of your field of view
With your arms extended straight out, parallel to Earth,
your fingers will point to the edges of the planet: your horizon
From 400 km up, about where the ISS orbits, 3% of the Earth's surface is within your horizon,
but the Earth will only take up about 140° of your vision
Your fingers would point to Earth's edges if you narrowed your arms' angles,
each by the width of two outstretched fists
One fist is about 10° across at arm's length
You can move your eyes from edge to edge horizontally here, but you can't quite take in the full width vertically
But from more than twice this altitude, 1000 km away, Earth is only 120° across
That's one less fist width each
This is perfect
That fits within our narrower vertical field of view
So, from 1000 km up (about 620 mi),
you can just start to see Earth as a complete disk right in front of you at once
However, only 7% of Earth fits within the horizon form up here
Images of Earth taken by satellites this far up, like the Suomi NPP, look kinda weird
I mean, North America doesn't actually take up this much of the globe
Earth's 120° width has been compressed to fit in an image much narrower
Compare Africa from its height to the famous blue marble picture taken from 45,000 km away
The latter looks more realistic, like looking at a globe on your desk
Geosynchronous satellites are about 35,000 km high
From their altitude, 43.4%—nearly a whole half—of Earth's surface is visible,
but the Earth only takes up a meager 17°
You could completely cover it with two outstretched palms
That's incredible
But what about from the Moon?
Well, from that far away, Earth is only about 2° across
You could block it out with your outstretched thumb
However, you can see more of Earth—you can see further around its curvature
From the Moon, 49% of Earth's surface is visible
Just 49
If you want to see 50, half of Earth's surface at once, you have to go even further away
In fact, you have to go infinitely far away, which you can't
The most of a sphere you can see at once with your own eyes is just half
But in the real world, way before you were actually infinitely far away,
the amount of light reaching you from Earth's surface
would become so small and infrequent that you wouldn't be able to see anything at all
Stars, like our Sun, are much brighter and bigger than the Earth,
but only a handful have, even with our best technology, been resolved as anything larger than just a single point
From 1/1000 of a light-year away, our own Sun would look like every other star in the sky:
a single point to the naked eye, only about as wide as R Doradus, the widest star in our sky
From 91 light-years away, the point of our Sun would dim to a level undetectable by the naked eye
It would disappear
Most of the stars in the night sky you can see with your naked eye are further away than that,
we can see them though because they're brighter and bigger than our own Sun,
which means if there's life out there, living in systems around the stars we've marvelled at
and written stories about since humanity began,
chances are, we are not part of their constellations or folklore
We're a dark patch in the sky to them,
an ignorable emptiness framing other stars, the ones they marvel at
while not knowing we're here, or that there is anything here
And as always, thanks for watching!
(Music reinforcing existential crisis)
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And, know this, I love you
Oh, and this Vsauce shirt is only available to Curiosity Box subscribers
This shirt comes in the latest box
If you sign up now, you will get this shirt, so long as you sign up before it sells out
The Curiosity Box is good for all brains
It comes to your door, 4 times a year, full of science gear and toys that I want you to have,
I want you to hold and learn from
Also, a portion of the proceeds from every box goes to Alzheimer's research
I'm incredibly proud of it
But what's going on on this shirt?
Well, it's modular multiplication around a circle
We have the numbers 1 to 40, around the outside of a circle, connected to their product with the number 4
So, 1 is connected to 4, 2 is connected to 8, 3 is connected to 12 and so on, even past 40
You could keep imagining the numbers continuing
For instance, 1 can become 41, 2 can become 42
And this emerges—the Vsauce V
Many other shapes can be made by using different multipliers or different numbers around the circle
Mathologer has a fantastic video on this topic, which you should check out
I have linked it down in the description
Thank you for being curious and as always, thanks for watching!