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At one point or another you might have heard that only a few centuries ago, people thought
the Earth was flat. People believed that if you sailed too far out, you would reach the
literal edge of the world and fall off. Well this is quite misleading as people have known
the Earth to be spherical since the time of ancient Greece. The earliest known evidence
for the concept of a spherical Earth can be traced back to Greek philosophers during the
6th century BC. A few centuries later, no educated person thought the world was anything
but round. This idea slowly spread and gradually became accepted as fact all across the globe.
And while some cultures held on to the flat-earth-idea for quite a while, by the time of the Middle Ages,
the Earth was most definitely a globe. Medieval books and illustrations repeatedly
make the point that the earth is round and not flat. The confusion actually comes from
historians looking back and misinterpreting certain events and literature.
While people may not have believed the Earth to be flat as much as we thought. For the
longest time, we definitely believed ourselves to be the center of the universe. It's called
the geocentric model and it actually makes a lot of sense. From our point of view down
here on the surface, it actually looks like the Sun, Moon, visible planets, and distant
stars orbit around a stationary Earth. It wasn't until the late 16th century that the
geocentric model was gradually superseded by the heliocentric model where the Sun is
the center and the Earth is simply one planet among many orbiting around it.
Earth is the only planet not named after a Greek or Roman god or goddess. The name comes
from old Germanic words such as ertha and ert. And while its name is of course different
in every language, what they all have in common is that almost every name derived from a word
that means "soil" or "ground". For example here in Sweden, the planets name is Jorden
and the word for soil is jord. The Latin names Terra and Tellus can also be used as synonyms.
We all know that one day here on Earth is 24 hours long and the reason we have days
in the first place is because the earth is rotating on it's own axis while orbiting the
sun. But if we do the calculations, we find that for the Earth to make one full revolution
it only takes 23:56:04. This is called a sidereal day and is actually not the way we calculate
one full day here on Earth. This is because, the unit of time known as day also has to
account for the orbit around our sun. Let's take this specific point on Earth. Now, let's
simulate a day passing by rotating the planet. Once the point reaches the same position,
one sidereal day has passed or 23:56:04. What makes a solar day 24 hours long is the location
of this spot relative to the sun. While the Earth has definitely made a full rotation,
it also moved a bit in it's year long orbit around the sun. Therefor it actually needs
to rotate a bit more so that this point is now facing the sun like it did when it started.
And just like a day isn't really 24 hours long, a year isn't really 365 days long. The
reason for this is not the same however. We count days based on the rotation of the Earth,
while the year is based on the orbital period around the sun. And this is the problem. The
day/night cycle has nothing to do with the yearly cycle. Yet a year is determined by
the day/night cycle. This result in one year being 365.2425 days long. This is where leap
years come into play. Every forth year we squeeze in an extra day at the end of February
because the Earth's spin and the Earth's orbit around the sun every so slightly overlap.
Without leap years, our calenders would get confused and summer would eventually be winter
and vice versa.
Liquid water is a crucial part for all life here on Earth. Yet the origin of our planet's
water remains unclear. More specifically, why do Earth have so much more liquid water
compared to almost every other body in the solar system. I say almost every other body,
because one of Jupiter's moons called Europa, may contain more than twice as much liquid
water found here on Earth. Even though it's smaller then our Moon. This subsurface ocean
is trapped under a vast sheet of ice and could potentially contain life.
While life may or may not be so abundant in the universe, the Earth is truly teaming with
it. It is everywhere and seems to somehow survive everything. Top of mount everest?
No problem. Bottom of the ocean? Of course. At the edge of the atmosphere? Sure. Inside
NASA and ESA clean rooms which are meant to be sterilized inhospitable environments?
Are you even fucking trying m8. What I'm saying is that life.. uh... finds a way. It truly
does. Let's take a walk outside and bring a spoon with you. Good. Now dig up some soil
and take a good look at it. This spoonful of soil contains more living organism than
there are humans on this planet. Soil is a paradise for tiny creatures eating and pooping
and reproducing their way toward glorious soil fertility. Luckily we can't see any of
that, otherwise I would've flipped my shit by now. In an equally mind-fuck fashion, for
every grain of sand on Earth, there are roughly 10,000 stars in the universe.
Welcome to Earth...
Texas. The only city on Earth named Earth. Well at least in English.
It has a population of around 1000 and was originally called Fairlawn. However they soon
learned of another city by that name so the townspeople sent in suggestions for a new
one, and thus Earth became the first Earth on Earth.
Most of us know that Mt. Everest is the tallest point on the planet. Well, no it isn't actually.
It's only the highest mountain by elevation above sea level. The tallest point on Earth,
as in either the greatest distance from the center or the least distance to space is
Mt. Chimborazo. This is because the Earth is not really a perfect sphere but something called
a spheroid. This basically means that the Earth is a bit thicker along the equator compared
to the poles. And as Mt. Chimborazo is very close to the equator it just barely beats Mt. Everest.
The Earth has been the home to every living thing in the universe that we know of. But
why is that? If the universe has existed for so many billions of years, why is space so
seemingly empty? Well, that's not exactly what this video about, and I have in fact
talked about this in numerous videos before, but a possible answer or perhaps clue to that
question is the Earth itself. Because Earth is extremely complicated. Its creation and
what lead to our existence is nothing short of an accident. Or rather a very long list
of accidents. It all started roughly 4.54 billion years ago when our solar system was
nothing but a gigantic cloud of dust and particles known as a solar nebula. Due to gravity, things
eventually started spinning and the sun began to take form in the center while planets and
smaller bodies formed around it. Out of shear luck, the Earth formed at just the right distance
so it would not be too hot or too cold for us humans to exist many eons later. The so
called habitable or Goldilocks zone. We where also fortunate enough to have a bro like Jupiter
to catch many nasty comets that could potentially hit the Earth and annihilate us. Much like
what happened to the dinosaurs. Early in its evolution the Earth was a hellish planet with
intense volcanism and frequent collisions with meteorites and other bodies. One of these
collisions is believed to have created the moon. The Earth collided with a body the size
of mars which ejected enormous amounts of debris into orbit. This debris eventually
clumped together to form the Moon. Not only that, but the collision itself is thought
to be responsible for tilting the Earth at an angle, giving us seasons. All the volcanic
activity during this period began the creation of Earth's atmosphere. In turn, the comets
brought with them ice that melted and helped to cool this hellish landscape to create the
Earth's crust and possibly the oceans. Roughly 3.8 billion years ago, the Earth had cooled
enough for life to take form. However, it wasn't until 2 billion years ago when photosynthetic
life began to appear, enriching the atmosphere with life essential oxygen.
We still don't know how life began on this planet,
but it's quite evident that a lot is required for it to begin. You can't just have an Earth
like planet and expect that to be enough. Of course, this is all assuming that an Earth
like planet is required for life to exist.
Oh and 63 Earths can fit inside Uranus.
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