00:00 Do you know how it all started 13.8 billion years ago with the Big Bang?
00:05 BAM!
00:06 No, no, wait, I can do better.
00:09 Pfft, never mind.
00:11 And the Universe has been expanding ever since.
00:14 At its young age, it was all made of gas, mostly helium and hydrogen.
00:20 For billions of years, the gas has expanded and cooled down.
00:24 Meanwhile, galaxies, stars, and other mysterious things in space we try to explore today formed
00:31 because of gravitational forces.
00:34 And in that chaos, just like in middle school, about 4.6 billion years ago, our magnificent
00:40 planet was born too.
00:42 It all started as a disk of gas and dust that orbited the young Sun, just the same way it
00:48 was with the rest of the planets in our solar system.
00:51 This disk consisted of dust particles of different sizes and gas.
00:57 They were circling the Sun at different speeds and in orbits that weren't stable and predictable.
01:02 They were bumping into each other all the time.
01:05 These particles grew from very small grains of dust into boulders, then later into bigger
01:10 objects called planetesimals that had a range from miles to hundreds of miles in diameter.
01:17 And these planetesimals that were orbiting the Sun within the disk had gravitational
01:22 force strong enough to pull other objects from the neighborhood out of their orbits
01:27 and collide with them.
01:29 As they were constantly hitting each other, they got bigger and bigger, until some got
01:34 to the size of thousands of miles in diameter.
01:38 That's nearly the size of Mars and the Moon.
01:40 We know these things because of meteorites.
01:43 They come from different places all over our solar system and bring all kinds of materials
01:49 to our planet, giving us something cool to study and learn about our solar system and
01:54 how it formed.
01:56 These materials include very small pieces of dust and rock that have gone through the
02:01 chaos and survived those rough times even before the planets were created.
02:07 Meteorites also brought pieces of asteroids and planetesimals left behind after the planet-forming
02:12 process ended.
02:14 As these objects were forming, some radioactive elements were left trapped inside the minerals
02:20 that, again, were part of them.
02:22 That's how scientists could tell how old they were.
02:26 But the final stage of Earth's formation, and generally this whole chaos that was happening
02:31 in our solar system, may have taken a little bit longer.
02:36 Possibly even up to a hundred million years more.
02:39 That's when the last enormous impact was, and the Earth finally reached its full size.
02:45 What actually happened is that it hit another object which was nearly as large as Mars.
02:51 This collision was so strong that the impact produced enough energy to vaporize some of
02:56 the metal and rock both from the Earth and the Mars-sized object.
03:01 And this vapor created a disk that was surrounding our planet.
03:05 It discooled and clumped together at some point, which is when we got our Moon.
03:11 Our Moon was the result of impact debris, which was a combination of hot gas and molten
03:17 rock.
03:18 There are some theories of how the Moon formed, though.
03:22 One claims it broke off from the Earth.
03:24 Another one says the Moon formed somewhere else in our solar system, and at some point,
03:30 as it was wandering around, it got so close to Earth that it ended up captured by its
03:35 gravity.
03:37 And fans of the third theory believe the Moon and the Earth formed at the same time, from
03:42 the same protoplanetary disk.
03:45 Before the Moon formed, the Earth was a much different place.
03:49 If you could have just one day on Earth without the Moon, you'd be first surprised by the
03:54 days and nights.
03:55 They wouldn't be as stable as they are today because the Moon helps to keep the Earth's
04:00 axis stable.
04:02 Days were shorter back then.
04:04 The Earth had been rotating much faster before the Moon formed.
04:08 Its gravitational pull slowed the rotation of our planet, which means days got longer.
04:14 The Earth's rotation is getting slower through time, but at a really small rate.
04:19 Some predictions say that in a billion years, a typical day will be between 25.5 and 31.7
04:28 hours long.
04:29 If 24 hours is not enough time for you, just wait a billion years.
04:34 But yeah, if you're the type of person that likes to take things slowly, you'd definitely
04:40 have to hurry back then.
04:41 Although there weren't many things you could do back then than to fill your time besides,
04:47 you know, sailing across the hot lava, collecting rocks, or hoping not to get hit in the head
04:53 by some fierce meteorite falling onto our planet.
04:59 But if you were patient enough, maybe you'd see something really cool – water coming
05:04 onto our planet for the first time.
05:07 There was a rain of fiery meteors coming from the sky, and they kept slamming into our young
05:12 Earth.
05:13 It looked devastating at first, but some of this falling debris probably held water.
05:20 Many believe the asteroids and comets that bumped into our home planet carried tiny amounts
05:25 of water, but considering this meteorite shower lasted more than 20 million years, maybe even
05:31 up to 200 million years, it's not that unusual that after a while puddles of water started
05:38 to collect across the surface.
05:41 And as the water evaporated within the atmosphere, it would fall back down, forming lakes, rivers,
05:47 seas, and eventually oceans.
05:50 Only at that point, there was a chance for some primitive life to evolve sometime in
05:54 the future.
05:55 Earth started its transition from a hot ball of magma to the world we know today.
06:02 Before that, it would be too hard for life to exist there.
06:06 Even if it had happened somehow, all those meteor and asteroid collisions would have
06:11 probably destroyed it.
06:13 Also, you wouldn't be able to survive without an oxygen tank.
06:17 The Earth did have an atmosphere, but it wasn't like the one we have today.
06:22 Scientists believe it was composed of water vapor, methane, ammonia, and some other gases
06:28 released from volcanic activity.
06:30 Basically, it was too toxic, since there were volcanic eruptions all the time.
06:37 And the temperatures were way higher, so just standing at these early stages of Earth wouldn't
06:42 be such a pleasant experience.
06:44 Also, there could even be some form of life at that time.
06:49 In its early stages, when everything was so chaotic, it wasn't covered in oceans, trees,
06:55 or stunning landscapes like today, but in molten magma.
06:59 I mean, the earliest form of life we know about are fossils of microorganisms found
07:05 in hydrothermal vents.
07:07 And they're thought to be 1.4 billion years old.
07:11 And scientists assume the earliest time for life to show on Earth could be 4.2 billion
07:16 years ago, give or take.
07:19 So with the right equipment, you could even see some single-celled organisms, like bacteria,
07:25 somewhere across our chaotic planet, even before the Moon was there.
07:30 The Moon's gravitational pull on the Earth creates tides in the ocean, which means it
07:35 probably helped mix and circulate ocean water, maybe even shape them.
07:41 The tides without the Moon would be much smaller, because the gravitational pull is what causes
07:46 the tides to rise and fall.
07:49 The Moon also affects life in the ocean.
07:52 Over time, animals in the ocean have changed and adapted to the changing water levels caused
07:58 by the Moon's gravity.
08:00 Even just the moonlight has a big effect on sea creatures.
08:04 For example, corals use the Moon's cycle to release their eggs at the same time and with
08:10 stronger tides to help carry the eggs.
08:13 Baby sea turtles use the Moon's light shining on the water to guide them from their nest
08:18 to the ocean.
08:19 Who knows which directions life on the Earth would've taken if, at some point billions
08:25 of years ago, we didn't get our lunar buddy to follow us along the way.
08:35 That's it for today!
08:36 So hey, if you pacified your curiosity, then give the video a like and share it with your
08:40 friends!
08:41 want more just click on these videos and stay on the bright side.
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