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The script and voiceover for this video were done by Fraser Cain, Publisher of Universe
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Today, Make sure you check out his channel after this video.
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Planet Earth. That shiny blue marble that has fascinated humanity since they first began
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to walk across its surface. And why shouldn't it fascinate us? In addition to being our
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home and the place where life as we know it originated, it remains the only planet we
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know of where life thrives. And over the course of the past few centuries, we have learned
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much about Earth, which has only deepened our fascination with it.
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But how much does the average person really know about the planet Earth? You've lived
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on Planet Earth all of your life, but how much do you really know about the ground underneath
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your feet? You probably have lots of interesting facts rattling around in your brain, but here
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are 10 more interesting facts about Earth that you may, or may not know.
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1. Plate Tectonics Keep the Planet Comfortable: Earth is the only planet in the Solar System
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with plate tectonics. Basically, the outer crust of the Earth is broken up into regions
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known as tectonic plates. These are floating on top of the magma interior of the Earth
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and can move against one another. When two plates collide, one plate will subduct (go
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underneath another), and where they pull apart, they will allow fresh crust to form.
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This process is very important, and for a number of reasons. Not only does it lead to
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tectonic resurfacing and geological activity (i.e. earthquakes, volcanic eruptions, mountain-building,
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and oceanic trench formation), it is also intrinsic to the carbon cycle. When microscopic
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plants in the ocean die, they fall to the bottom of the ocean.
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Over long periods of time, the remnants of this life, rich in carbon, are carried back
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into the interior of the Earth and recycled. This pulls carbon out of the atmosphere, which
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makes sure we don't suffer a runaway greenhouse effect, which is what happened on Venus. Without
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the action of plate tectonics, there would be no way to recycle this carbon, and the
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Earth would become an overheated, hellish place.
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2. Earth is Almost a Sphere: Many people tend to think that the Earth is
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a sphere. In fact, between the 6th cenury BCE and the modern era, this remained the
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scientific consensus. But thanks to modern astronomy and space travel, scientists have
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since come to understand that the Earth is actually shaped like a flattened sphere (aka.
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an oblate spheroid). This shape is similar to a sphere, but where
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the poles are flattened and the equator bulges. In the case of the Earth, this bulge is due
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to our planet's rotation. This means that the measurement from pole to pole is about
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43 km less than the diameter of Earth across the equator. Even though the tallest mountain
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on Earth is Mount Everest, the feature that's furthest from the center of the Earth is actually
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Mount Chimborazo in Ecuador.
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3. Earth is Mostly Iron, Oxygen and Silicon: If you could separate the Earth out into piles
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of material, you'd get 32.1 % iron, 30.1% oxygen, 15.1% silicon, and 13.9% magnesium.
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Of course, most of this iron is actually located at the core of the Earth. If you could actually
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get down and sample the core, it would be 88% iron. And if you sampled the Earth's
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crust, you'd find that 47% of it is oxygen. 4. 70% of the Earth's Surface is Covered
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in Water: When astronauts first went into the space,
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they looked back at the Earth with human eyes for the first time. Based on their observations,
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the Earth acquired the nickname the “Blue Planet:. And it's no surprise, seeing as
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how 70% of our planet is covered with oceans. The remaining 30% is the solid crust that
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is located above sea level, hence why it is called the “continental crust”.
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5. The Earth's Atmosphere Extends to a Distance of 10,000 km:
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Earth's atmosphere is thickest within the first 50 km from the surface or so, but it
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actually reaches out to about 10,000 km into space. It is made up of five main layers – the
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Troposphere, the Stratosphere, the Mesosphere, the Thermosphere, and the Exosphere. As a
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rule, air pressure and density decrease the higher one goes into the atmosphere and the
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farther one is from the surface. The bulk of the Earth's atmosphere is down
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near the Earth itself. In fact, 75% of the Earth's atmosphere is contained within the
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first 11 km above the planet's surface. However, the outermost layer (the Exosphere)
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is the largest, extending from the exobase – located at the top of the thermosphere
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at an altitude of about 700 km above sea level – to about 10,000 km (6,200 mi). The exosphere
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merges with the emptiness of outer space, where there is no atmosphere.
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The exosphere is mainly composed of extremely low densities of hydrogen, helium and several
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heavier molecules – including nitrogen, oxygen and carbon dioxide. The atoms and molecules
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are so far apart that the exosphere no longer behaves like a gas, and the particles constantly
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escape into space. These free-moving particles follow ballistic trajectories and may migrate
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in and out of the magnetosphere or with the solar wind.
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Want more planet Earth facts? We're halfway through. Here come 5 more!
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6. The Earth's Molten Iron Core Creates a Magnetic Field:
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The Earth is like a great big magnet, with poles at the top and bottom near to the actual
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geographic poles. The magnetic field it creates extends thousands of kilometers out from the
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surface of the Earth – forming a region called the “magnetosphere“. Scientists
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think that this magnetic field is generated by the molten outer core of the Earth, where
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heat creates convection motions of conducting materials to generate electric currents.
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Be grateful for the magnetosphere. Without it, particles from the Sun's solar wind
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would hit the Earth directly, exposing the surface of the planet to significant amounts
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of radiation. Instead, the magnetosphere channels the solar wind around the Earth, protecting
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us from harm. Scientists have also theorized that Mars' thin atmosphere is due to it
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having a weak magnetosphere compared to Earth's, which allowed solar wind to slowly strip it
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away. 7. Earth Doesn't Take 24 Hours to Rotate
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on its Axis: It actually takes 23 hours, 56 minutes and
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4 seconds for the Earth to rotate once completely on its axis, which astronomers refer to as
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a Sidereal Day. Now wait a second, doesn't that mean that a day is 4 minutes shorter
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than we think it is? You'd think that this time would add up, day by day, and within
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a few months, day would be night, and night would be day.
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But remember that the Earth orbits around the Sun. Every day, the Sun moves compared
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to the background stars by about 1° – about the size of the Moon in the sky. And so, if
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you add up that little motion from the Sun that we see because the Earth is orbiting
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around it, as well as the rotation on its axis, you get a total of 24 hours.
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This is what is known as a Solar Day, which – contrary to a Sidereal Day – is the
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amount of time it takes the Sun to return to the same place in the sky.
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8. A year on Earth isn't 365 days: It's actually 365.2564 days. It's this
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extra .2564 days that creates the need for a Leap Year once ever four years.
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9. Earth has 1 Moon and 2 Co-Orbital Satellites: As you're probably aware, Earth has 1 moon
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(aka. The Moon). Plenty is known about this body and we have written many articles about
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it, so we won't go into much detail there. But did you know there are 2 additional asteroids
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locked into a co-orbital orbits with Earth? They're called 3753 Cruithne and 2002 AA29,
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which are part of a larger population of asteroids known as Near-Earth Objects (NEOs).
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The asteroid known as 3753 Cruithne measures 5 km across, and is sometimes called “Earth's
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second moon”. It doesn't actually orbit the Earth, but has a synchronized orbit with
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our home planet. It also has an orbit that makes it look like it's following the Earth
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in orbit, but it's actually following its own, distinct path around the Sun.
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Meanwhile, 2002 AA29 is only 60 meters across and makes a horseshoe orbit around the Earth
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that brings it close to the planet every 95 years. In about 600 years, it will appear
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to circle Earth in a quasi-satellite orbit. Scientists have suggested that it might make
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a good target for a space exploration mission. 10. Earth is the Only Planet Known to Have
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Life: We've discovered past evidence of water
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and organic molecules on Mars, and the building blocks of life on Saturn's moon Titan. We
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can see amino acids in nebulae in deep space. And scientists have speculated about the possible
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existence of life beneath the icy crust of Jupiter's moon Europa and Saturn's moon
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Titan. But Earth is the only place life has actually been discovered.
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But if there is life on other planets, scientists are building the observatories, space telescopes
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and missions that will help find it. Huge new telescopes are under construction that
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will directly observe the atmospheres of planets orbiting other stars, in search of biosignatures
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- evidence of life. Radio telescopes scan the skies for signals from extraterrestrials.
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And new space missions are in the works to search for evidence of life on Mars and the
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icy moons of the Solar System."
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But for now, Earth remains the only place we know of where there's life. Now that
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is an interesting fact!
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Huge thanks again to Fraser Cain for the script and for being the voiceover of this video,
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click on the link here or in the description to check out his amazing channel.