Placeholder Image

字幕列表 影片播放

  • Today we are answering an age-old very  scientific and important question:  

  • What if the moon crashes into earth? It’s more  interesting and weird than you probably think.  

  • Let's start with the basics: Why isn't the  Moon on its way to crash into us already?

  • We know that earth’s gravity pulls everything  towards it, including the Moon, but somehow,  

  • it stays up, as if suspended by some opposite  force. But there is no other force countering  

  • gravity - instead, the trick to staying up  is a ‘sidewaysmotion that we call an orbit.

  • You see orbits every day: when you throw  a ball it makes a tiny little orbit.  

  • The only difference between that ball’s  orbit and the moon’s is that the ball  

  • eventually hits the groundBasically, the reason is speed.

  • If you could throw your ball fast enough, it  would bend around the world and come back to you.  

  • If there was no air slowing it down, it could  orbit forever. And this is what the moon does:

  • Falling sideways around earth, very fast, with no  air slowing it down. Orbiting earth every 27 days,  

  • at 3600 km/h. So for the moon to just stop  in its orbit and plummet to the earth would  

  • break more laws of physics than we have time  to explain. So how do we crash it into earth?

  • In a nutshell, to change an object’s  orbit, you need to change its speed,  

  • which changes where gravity takes it. But  even small changes require enormous forces,  

  • which is why all the large objects in  the solar system are so stable nowadays.

  • According to science, the moon is big and very  massive. Even igniting billions of rocket engines  

  • all over its surface would barely move the Moon. It looks like nothing short of magic will make  

  • the moon fall. So well use a magic  spell that slows down the moon so much  

  • that it changes its orbit and spirals towards  earth. To get the most from the experience,  

  • the moon will take exactly one year before  it hits earth. Ready? 3. 2. 1. *Magic

  • Month 1

  • For the first few days, nothing really  changes. The moon gets a tiny bit brighter  

  • and scientists get confused, but the rest  of us don’t notice anything different.

  • The only noticeable real effect of  the moon on the earth are the tides.  

  • Tides exist because while earth pulls on the  moon, the moon’s gravity pulls back on the earth.  

  • Since the strength of gravity gets weaker  with distance, different parts of the earth  

  • feel a slightly different pull. Which  causes the earth, especially the oceans,  

  • to bulge when the moon is above them, and  contract a little on the sides when it’s  

  • not. As earth rotates every day underneath  the moon, the moon’s influence fluctuates,  

  • causing the water-level of the oceans to rise  and fall by about half a meter twice a day.

  • But with the moon drawing ever closer, high tide  gets higher every day. At first barely noticeable,  

  • within a month the moon has covered half the  distance to the earth and ocean tides have  

  • grown to 4 meters. Everyday high tide  comes and waves flood coastal cities.  

  • And there is no end in sight. With the moon  drawing ever closer, tides rise ever higher,  

  • inundating another city and more  inhabited land with salty water every day.

  • Month 2

  • By the end of month 2 the moon has covered  two-thirds of the distance to earth,  

  • and global infrastructure is crumbling as  tides rise above ten metersdisplacing up  

  • to a billion people who happen  to live near the coastlines.

  • As ports become inoperable shipping grinds  to a halt. Not only will it slow down the  

  • delivery of Kurzgesagt products but  also less exciting things like food.  

  • Global communications fall into disarray – 95% of  the internet is carried by ocean-crossing cables,  

  • and while these largely don’t mind the watertheir terminals on land do. Living inland  

  • doesn’t guarantee safety either, tidal  bores cause rivers to flow backwards,  

  • carrying saltwater to contaminate  surface and groundwater supplies.

  • Gas shortages follow, as oil refineries near  the coast are abandoned. Countries are left  

  • with the supplies they had on their shelves  and strict rationing will begin. In the cities,  

  • chaos reigns during the  scavenging hours of low tide,  

  • while survivors take refuge in  highrises when the water returns.

  • Month 3

  • Three months in and the moon is  close enough to disrupt communication  

  • and navigation satellites. While it is normally  far too distant for its gravity to cause any  

  • major problems for our satellites, the closer  it gets the more warped their orbits become.  

  • As their fuel for orbital corrections runs  out, satellites careen out of control.

  • Month 4 - 5 On earth, the tides are  

  • rapidly growing to about 30 meters and will be  reaching 100 m in height in a few short weeks.  

  • At low tide, the ocean recedes hundreds of  kilometers, exposing the continental shelf  

  • like vast deserts, while at high tide walls of  water drown agriculture, houses and skyscrapers.

  • And now, almost five months in, the  apocalypse has finished its warm-up act.

  • Since the oceans are on average only 3 kilometers  deep, the tides have reached their maximum. Up  

  • until now, the water in the oceans could flowabsorbing most of the moon's gravitational  

  • squeezing, but now the earth itself is really  feeling the squeeze of the ever approaching moon.  

  • These aren’t so much tides ofwater’, but  tides ofrock.’ The squeezing of the planet,  

  • combined with the weight of quintillions of tons  of water sloshing on and off the tectonic plates,  

  • creates enormous stresses below and begins to  cause earthquakes of increasing magnitude and  

  • intensity. It’s impossible to say how serious  these earthquakes might be or where they occur,  

  • but like a child jumping on their bed  until it breaks, no good can come of it.

  • Strong tidal forces lead to volcanism  on other planets and moons. On earth,  

  • squeezing the planet disrupts the  magma reservoirs inside the crust,  

  • triggering sizable, climate-altering eruptions in  Chile, New Zealand, Yellowstone, and elsewhere.

  • Meanwhile, watching patiently above is the moonStill no bigger in the sky than a small cloud.  

  • Within 75,000 km of earth, it is bright enough  to illuminate the night sky like twilight.

  • Month 6 - 7

  • After half a year, the moon is entering the space  once occupied by geosynchronous satellites where  

  • it orbits earth every 24 hours. It appears  to float at one spot in the sky, unmoving,  

  • cycling through a full set of phases every  day, but only visible to half the planet.  

  • With the moonstationaryabove the  earth, the tides seem to freeze in  

  • placehalf the world flooded, half with  its water seemingly returned to the sea,  

  • as if Earth is holding its  breath to prepare for the worst.

  • As the moon sinks further, you might wonder if  its gravity would overpower Earth’s, pulling you 

  • up and ending your misery? Fortunately not.  

  • The earth’s surface gravity is about  6 times stronger than the moon’s,  

  • so even if the moon were hovering right on top  of you, you would still stay on the ground.

  • On the moon things are different though: the near  side of the moon is more strongly affected by  

  • earth’s gravity, so during the next few months, it  starts to stretch forward towards the earth, into  

  • something of an egg, triggering deep moonquakes  as the lunar rock flexes and changes shape. Though  

  • barely noticeable now, thissquishwill grow  to hundreds of kilometers in a matter of months.

  • Month 8 - 11

  • At this point the apocalypse has arrived and  we can summarize the months before the crash  

  • aseverybody left has a really bad time”.  The tides sweeping over the Earth slow down  

  • and then reverse their direction because the  moon now orbits earth faster than it rotates.

  • The planet will experience an abundance of  earthquakes and volcanism. Massive amounts of  

  • volcanic aerosols rise high into the stratosphereshiny enough to reflect sunlight back into space.  

  • What little light gets through is rust-red and  is periodically diminished by daily eclipses.  

  • The result is a rapid global cooling, with  acid rains and summer snows killing even  

  • the hardiest plants.The clock runs out  on civilization. Billions have perished  

  • while an egg-shaped moon is still drawing  closer. Let’s get ready for the grand finale.

  • Month 12

  • Finally, at the end of the year,, the moon  has reached the Roche limit. That’s the point  

  • where Earth’s gravitational pull on the Moon is  stronger than the Moon’s own gravity. Things on  

  • the lunar surface start falling towards Earth  and by the time it crosses 10,000 km the entire  

  • moon disintegrates into rubble, smearing itself  into a massive ring system around the earth.

  • Fortunately, the moon’s disintegration  means the misery on Earth has ended.  

  • No moon means the general apocalyptic nature  of things comes to a halt. The oceans recede,  

  • flowing off the land one last time.

  • Any survivors are treated to a view  of tremendous arches spanning the sky,  

  • glimmering in the sunlight, illuminating  the night sky more brilliantly than any  

  • full moon ever could, while meteor  showers of moondust fill the sky.

  • It’s hard to say what happens nextbut the tranquility may be short-lived.  

  • If too much moondust rains down, friction  heats the atmospherepossibly boiling the  

  • oceans. If not, the enormous  shadows cast by the rings,  

  • combined with all the volcanic and meteoric  aerosols, block even more sunlight,  

  • and a period of runaway cooling could begin  that freezes much of earth’s surface solid.

  • In any case, at some point people will  emerge againfrom submarines or bunkers  

  • or mountaintops. They will not have a great time  before rebuilding civilization and their success  

  • is not guaranteedbut at least they will  try to do so with beautiful rings in the sky.

  • So how do you calculate that sort of thing? Well,  

  • you just need a bit of insanity and some  maths. If you need to brush on the latter:  

  • Our friends from Brilliant are the perfect coaches  to turn your curiosity into practical skills.

  • Brilliant is a problem-solving website  and app that makes science accessible 

  • with a hands-on approach. More than 60 interactive  courses likeThe joy of problem solvingor  

  • Scientific thinkinggive you the tools to crack  problems in math, science and computer science in  

  • a way that feels more like playing a game than  doing homework. Lessons will surprise you with  

  • storytelling, code-writing tasks and interactive  challengesbasically using whatever keeps you  

  • interested and entertained. All the content is  interactive: instead of just reading and listening  

  • to explanations, you drag and drop, manipulate  shapes and diagrams, make selections and answer  

  • questions. This way you learn something almost  without you noticing it. And tiny step by step  

  • youll build up your long-term understanding  of science and get closer to your STEM goals.

  • To start looking at the world of  science from a different perspective,  

  • go to Brilliant.org SlashNutshell and sign  up for free. And there’s an extra perk for  

  • kurzgesagt viewers: the first 200 people to use  the link get 20% off their annual membership,  

  • which unlocks all of Brilliant’s courses  in math, science, and computer science.

  • At kurzgesagt we love to create things that seem  

  • impossible at firstBrilliant can  help you acquire the skills to do that.

  • This year we will release 3 very special limited  edition pins. The first one is this very shiny  

  • Moon Crash Pin Set. Pre-order is available  for only 72h, so you can order it now and then  

  • never again. Be sure to watch out for pin number  2 and 3 to complete your 12,022 collection.

Today we are answering an age-old very  scientific and important question:  

字幕與單字

單字即點即查 點擊單字可以查詢單字解釋

A1 初級 美國腔

如果月亮撞上地球會發生什麼事?(What Happens if the Moon Crashes into Earth?)

  • 306 19
    吳鑫陽 發佈於 2022 年 03 月 22 日
影片單字