0:03 today we are answering an age-old very
0:06 scientific and important question what
0:09 if the moon crashes into Earth it's more
0:12 interesting and weird than you probably
0:15 think let's start with the basics why
0:17 isn't the moon on its way to crash into us
0:26 already we know that Earth's gravity
0:28 pulls everything towards it including
0:31 the moon but somehow it stays up as if
0:34 suspended by some opposite Force but
0:36 there is no other Force countering
0:39 gravity instead the trick to staying up
0:41 is a sideways motion that we call an
0:44 orbit you see orbits every day when you
0:46 throw a ball it makes a tiny little
0:48 orbit the only difference between the
0:50 ball's orbit and the moon's is that the
0:53 ball eventually hits the ground
0:57 basically the reason is speed if you
0:59 could throw your ball fast enough it
1:00 would bend around the the world and come
1:03 back to you if there were no air slowing
1:06 it down it could orbit forever and this
1:08 is what the moon does falling sideways
1:11 around Earth very fast with no air
1:14 slowing it down orbiting Earth every 27
1:18 days at 3,600 km an hour so for the moon
1:20 to just stop in its orbit and plummet to
1:22 the Earth would break more laws of
1:25 physics than we have time to explain so
1:27 how do we crash it into Earth in a
1:30 nutshell to change an object's or it you
1:32 need to change its speed which changes
1:35 where gravity takes it but even small
1:38 changes require enormous forces which is
1:40 why all the large objects in the solar
1:42 system are so stable
1:44 nowadays according to science the moon
1:47 is big and very massive even igniting
1:49 billions of Rocket engines all over its
1:52 surface would barely move the Moon it
1:54 looks like nothing short of magic will
1:56 make the moon fall so we'll use a magic
1:59 spell that slows down the moon so much
2:01 that it changes its orbit and spirals
2:04 towards Earth to get the most from the
2:06 experience the moon will take exactly 1
2:13 year before it hits Earth ready 3 2 1
2:15 1
2:17 magic month
2:20 one for the first few days nothing
2:22 really changes the moon gets a tiny bit
2:24 brighter and scientists get confused but
2:26 the rest of us don't notice anything
2:28 different the only noticeable real
2:30 effect of the moon on the Earth are the
2:33 tides Tides exist because while Earth
2:35 pulls on the moon the moon's gravity
2:37 pulls back on the earth since the
2:39 strength of gravity gets weaker with
2:40 distance different parts of the earth
2:43 feel a slightly different pull which
2:45 causes the Earth especially the oceans
2:47 to bulge when the moon is above them and
2:49 contract a little on the sides when it's
2:51 not as Earth rotates every day
2:53 underneath the moon the moon's influence
2:55 fluctuat causing the water level of the
2:57 oceans to Rise and Fall by about half a
3:00 meter twice a day but with the moon
3:02 drawing ever closer high tide gets
3:05 higher every day at first barely
3:07 noticeable within a month the moon has
3:09 covered half the distance to the Earth
3:12 and ocean tides have grown to 4 M every
3:15 day high tide comes and waves flood
3:17 coastal cities and there's no end in
3:20 sight with the moon drawing ever closer
3:22 Tides rise ever higher inundating
3:25 another city and more inhabited land
3:30 with salty water every day month two
3:32 by the end of month 2 the moon has
3:34 covered 2/3 of the distance to Earth and
3:37 Global infrastructure is crumbling as
3:40 Tides rise above 10 m displacing up to a
3:42 billion people who happen to live near
3:44 the coastlines as ports become
3:47 inoperable shipping grinds to a halt not
3:49 only will it slow down the delivery of
3:52 quazar products but also less exciting
3:54 things like food Global Communications
3:57 fall into disarray 95% of the internet
4:00 is carried by ocean Crossing cables and
4:02 while these largely don't mind the water
4:05 their terminals on land do living in
4:07 land doesn't guarantee safety either
4:09 tidal boards cause rivers to flow
4:11 backwards carrying salt water to
4:14 contaminate surface and groundwater
4:16 supplies gas shortages follow as all
4:19 refineries near the coast are abandoned
4:21 countries are left with the supplies
4:23 they had on their shelves and strict
4:26 rationing will begin in the cities chaos
4:28 rains during the Scavenging hours of low
4:31 tide while survivors take refuge in
4:33 highrises when the water
4:36 returns month three 3 months in and the
4:38 Moon is close enough to disrupt
4:41 communication and navigation satellites
4:43 while it's normally far too distant for
4:45 its gravity to cause any major problems
4:47 for our satellites The Closer it gets
4:50 the more warped their orbits become as
4:52 their fuel for orbital Corrections Runs
4:55 Out satellites coren out of
4:58 control months four and
5:01 five on Earth the tides are rapidly
5:04 growing to about 30 m and will be
5:06 reaching 100 m in height in a few short
5:09 weeks at low tide the ocean recedes
5:11 hundreds of kilometers exposing the
5:14 continental shelf like vast deserts
5:16 while at high tide walls of water drown
5:18 agriculture houses and
5:22 skyscrapers and now almost 5 months in
5:24 the apocalypse has finished its warmup
5:27 act since the oceans are on average only
5:29 3 km deep the tides have reached their
5:32 maximum up until now the water in the
5:34 oceans could flow absorbing most of the
5:36 moon's gravitational squeezing but now
5:38 the Earth itself is ready feeling the
5:41 squeeze of the ever approaching Moon
5:44 these aren't so much tides of water but
5:46 tides of rock the squeezing of the
5:48 planet combined with the weight of
5:50 quenti of tons of water sloshing on and
5:53 off the tectonic plate creates enormous
5:55 stresses below and begins to cause
5:58 earthquakes of increasing magnitude and
6:00 intensity it's impossible ble to say how
6:02 serious these earthquakes might be or
6:04 where they occur but like a child
6:06 jumping on their bed Until It Breaks no
6:09 good can come of it strong tidal forces
6:11 lead to volcanism on other planets and
6:13 moons on Earth squeezing the planet
6:16 disrupts the magma reservoirs inside the
6:18 crust triggering sizable climate
6:21 altering eruptions in Chile New Zealand
6:23 Yellowstone and
6:25 elsewhere meanwhile watching patiently
6:29 above is the moon still no bigger in the
6:33 sky than a small Cloud within 75,000 km
6:34 of Earth it is bright enough to
6:37 illuminate the night sky like Twilight
6:39 months 6 and
6:42 7 after half a year the Moon is entering
6:43 the space once occupied by
6:45 geosynchronous satellites where it
6:48 orbits Earth every 24 hours it appears
6:51 to float at one spot in the sky unmoving
6:53 cycling through a full set of phases
6:55 every day but only visible to half the
6:58 planet with the moon stationary above
7:00 the Earth the tide it seemed to freeze
7:03 in place half the world flooded half
7:05 with its water seemingly returned to the
7:07 Sea as if Earth is holding its breath to
7:10 prepare for the worst as the moon sinks
7:12 further you might wonder if its gravity
7:14 would overpower Earths pulling you up
7:18 and ending your misery fortunately not
7:20 the Earth's surface gravity is about six
7:22 times stronger than the moon so even if
7:24 the moon were hovering right on top of
7:27 you you would still stay on the ground
7:29 on the moon things are different though
7:31 the near Side of the Moon is more
7:33 strongly affected by Earth's gravity so
7:35 during the next few months it starts to
7:37 stretch forward towards the earth into
7:39 something of an egg triggering deep
7:41 moonquakes as the lunar Rock flexes and
7:44 changes shape though barely noticeable
7:47 now this squish will grow to hundreds of
7:48 kilometers in a matter of
7:53 months Months 8 to 11 at this point the
7:55 apocalypse has arrived and we can
7:58 summarize the months before the crash as
8:01 everybody left has a bad time the tides
8:03 sweeping over the Earth slow down and
8:06 then reverse their Direction because the
8:09 moon now orbits Earth faster than it
8:11 rotates the planet will experience an
8:14 abundance of earthquakes and volcanism
8:16 massive amounts of volcanic Aerosoles
8:18 rise High into the stratosphere shiny
8:20 enough to reflect sunlight back into
8:22 space what little light gets through is
8:25 rust red and is periodically diminished
8:28 by daily eclipses the result is a rapid
8:30 global cooling with acid rains and
8:32 summer snows killing even the hardest
8:35 plants the clock runs out on
8:37 civilization billions have perished
8:39 while an x-shaped moon is still drawing
8:42 closer let's get ready for the grand
8:44 finale month
8:47 12 finally at the end of the year the
8:50 moon has reached the rash limit that's
8:52 the point where Earth's gravitational
8:54 pull on the moon is stronger than the
8:57 moon's own gravity things on the lunar
8:59 surface start falling towards Earth and
9:01 and by the time it crosses 10,000 km the
9:04 entire Moon disintegrates into Rubble
9:06 smearing itself into a massive ring
9:09 system around the earth fortunately the
9:11 moon's disintegration means the misery
9:14 on Earth has ended no moon means the
9:16 general apocalyptic nature of things
9:19 comes to a halt the oceans recede
9:23 flowing off the land one last time any
9:25 survivors are treated to a view of
9:28 tremendous arches spanning the sky
9:30 glimmering in the Sun light Illuminating
9:32 the night sky more brilliantly than any
9:34 full moon ever could while meteor
9:37 showers of moond dust fill the sky it's
9:39 hard to say what happens next but the
9:42 Tranquility may be shortlived if too
9:44 much moond dust rains down friction
9:46 heats the atmosphere possibly boiling
9:50 the oceans if not the enormous Shadows
9:52 cast by the Rings combined with all the
9:55 volcanic and meteoric aerosols block
9:57 even more sunlight and a period of
9:59 runaway cooling could begin the freezes
10:06 solid in any case at some point people
10:09 will emerge again from submarines or
10:11 bunkers or
10:13 mountaintops they will not have a great
10:16 time before rebuilding civilization and
10:19 their success is not guaranteed but at
10:20 least they'll be trying to do so with
