Subtitles section Play video
-
Hey there!
-
Welcome to Life Noggin.
-
Right now you're probably watching this video from somewhere on Earth… that big,
-
round, beautiful planet you humans call home.
-
But how do you know the Earth is round?
-
Your senses would tell you that it's flat.
-
After all, if you stand in a large field, it actually looks pretty flat.
-
And if you walk through that field, it doesn't feel like you're going over a curve.
-
Could it be that the Earth is actually flat?
-
Well, let's try an experiment.
-
Say you're standing in a field outside of Chicago.
-
If the Earth is flat, you should be able to see southwest and see some of the tallest
-
points in the United States, the Rocky Mountains.
-
But the thing is, you can't.
-
That's because of the curvature of the Earth.
-
You'll notice a similar problem if you stand on a seashore and try to watch a boat sail
-
away.
-
After a while, it will disappear from view.
-
And not only that, but the bottom of the boat will vanish before the top as it
-
goes over what's called the horizon line — the place where the sky meets the Earth.
-
For someone who is six feet tall, the horizon line is only three miles away.
-
But the higher up you are, the farther you can see over the Earth's curve.
-
This is why standing on a tall mountain might allow you to see over 100 miles while standing
-
in a field will only let you see a short distance.
-
It also means that taller people can see slightly farther than shorter people.
-
Good thing my animator can make me any height!
-
See, I'm like that one ant dude.
-
The thing is, none of this is new information.
-
We've known about the planet's curvature for over 2000 years.
-
The Ancient Greeks figured out that the Earth is round based on several pieces of evidence,
-
including their observations of ships going over the horizon line. The scientist Aristotle,
-
writing in 350 BCE, noted that during an eclipse, the Earth makes a round shadow on the moon.
-
He also realized that stars appear in different places depending on where you are standing.
-
For example, he saw stars in Egypt that weren't visible farther north.
-
Roughly 100 years later, humans got their first measurements of the Earth's curve
-
from another Greek mathematician, Eratosthenes.
-
He had heard of a city in southern Egypt where, at noon on the summer solstice, the sun was
-
directly overhead and the buildings cast no shadows.
-
But at the same time in the northern city of Alexandria, the buildings DID cast shadows.
-
meaning the sun was at a different angle in the sky.
-
On the day of the solstice, Eratosthenes stuck a stick in the ground in Alexandria and measured
-
the angle of its shadow.
-
Using the distance between the two cities, he was able to calculate the curvature of
-
the Earth!
-
You could actually perform this same experiment if you have a friend living a few miles away.
-
Or, if your friend is several hours west, you can get more proof that the Earth is round
-
by calling them at sunset and asking how the sky looks.
-
It will still be daylight there because of the Earth's curve.
-
And there's one more piece of clear evidence for the planet's shape — pictures taken
-
from space.
-
Maybe you're not on Earth after all and are actually watching this video from the
-
space station… in which case, please leave a comment, because that's so cool.
-
If that's true, you'll have a bird's-eye view of this giant blue and green globe.
-
What a beautiful place to live.
-
So what other myths about Earth do you want me to explore?
-
Let me know in the comment section below.
-
Do you love science?
-
Do you love video games?
-
If so, you'll HAVE to check out Play Noggin,
-
which is an excellent combination of the two.
-
Julian recently explored the idea of mind control.
-
Check it out!
-
If the colander our protagonist puts on his head allows him to hack into the mind of his less intellectual friends,
-
then in theory, he could exercise control over their actions at a basic level, it doesn't sound too complicated.
-
In order to control the activity in an area of the brain, you need to stimulate it with energy.
-
My name is Blocko, this has been Life Noggin, don't forget to keep on thinking