Nat Geo_Moon Mysteries
Transcript
00:00Imagine our world, ravaged by hurricane force winds, with temperatures swinging from scorching
00:11heat to freezing cold.
00:16Imagine the day lasting just six hours on a world where only primitive life forms evolve.
00:24This could be our planet if the Earth had no moon.
00:46The moon.
00:47An 81 million billion ton lump of rock and dust.
00:53More than 2,100 miles in diameter, orbiting almost a quarter of a million miles above
00:59our heads.
01:01It is the second brightest object in our skies, with temperatures ranging from 250 degrees
01:08down to minus 380 degrees and lower.
01:14Its gravity is a sixth of that of Earth.
01:17Moons soar to 16,000 feet, and millions of craters litter the dust-dry surface, where
01:24no liquid water has ever been found.
01:27This is not a hospitable place.
01:34And yet, we associate the moon with romance and mystery.
01:39The man in the moon enraptures lovers all over the world, and feeds our hunger for supernatural
01:45myths and legends.
01:50We are far from alone in having a moon.
01:53There are at least 135 other moons orbiting the planets in our solar system.
01:59Saturn has the most, with 46.
02:02While we have at least 10 mysterious bodies orbiting our planet, five are asteroids caught
02:08temporarily by the Earth's gravitational field, and four are probably remnants of the Apollo
02:1412 rocket.
02:19The tenth and largest is our moon.
02:24Since long before the birth of humankind, the moon has been the Earth's constant companion.
02:30But until relatively recently, we've known little of its true nature, or even how it
02:36was created.
02:41There are several competing theories.
02:44One suggests that the moon is merely an asteroid or planet trapped by the Earth's gravity.
02:52Another ascribes the creation to a giant impact on Earth, ejecting masses of material that
02:59formed the moon.
03:02Clues as to which theory is more likely to be correct came when men first landed on the
03:08moon and started unlocking the secrets of creation buried within the lunar rocks.
03:145, 4, 3, 2, 1, 0, liftoff.
03:21I'm going to step off the land now.
03:28That's one small step for man, one giant leap for mankind.
03:34Between 1969 and 1972, six missions blasted off to the moon.
03:40Wow, what a place.
03:42What a view, isn't it, John?
03:45It's absolutely unreal.
03:47Only 12 humans have ever walked on the moon.
03:52But these astronauts did more than just rewrite history.
03:56They also returned with samples of lunar rock.
04:00These moon rocks are amazingly similar to Earth rocks, but they contain far less iron.
04:07This seemingly small difference offers a huge clue as to how the moon was created.
04:15It shows that the moon started with a bang.
04:22Let's step back four and a half billion years in Earth's history.
04:27The moon does not yet exist.
04:30The inner solar system has about twice as many planets as the four that exist today.
04:37Many of them are on a crash course to destruction.
04:41Among them is a planet about half the size of Earth, since named Theia, who in Greek
04:47mythology was the goddess mother of the moon.
04:52The two bodies are on a collision course.
04:55Inexorably, Theia rushes closer and closer to Earth.
05:12The approaching planet is a terrifying sight.
05:20Astrophysicist Jeff Taylor studies the moon's fiery birth.
05:24He describes the view from Earth as Theia races toward it.
05:28It might have started looking like a star or a pretty big star, but then as it got closer
05:34and closer, this thing would get bigger and bigger and bigger and bigger and bigger until
05:39it just filled the sky moments before the big impact.
05:44And then everything would be gone for you as a witness, and there would be a giant flash
05:50because everything would be white hot.
05:52And if you were standing, a friend of yours, on the other side of the Earth, they would
05:56see the flash in the atmosphere and feel gigantic earthquakes passing through the Earth.
06:03Theia is 4,000 miles in diameter.
06:07To put its size in perspective, the meteorite thought to have wiped out the dinosaurs was
06:12about six miles across.
06:16Theia is traveling at 25,000 miles per hour.
06:19That's about 20 times faster than a supersonic jet.
06:23This is an object that is the size of Mars, which is about half of the Earth's diameter.
06:30So it's a gigantic event of unimaginable power.
06:36As the planets get closer, their immense gravitational fields rip each other's outer layers to pieces.
06:44Then they catastrophically collide.
07:01The impact is equivalent to billions of megaton bombs.
07:14The impact shears off continent-sized sections of the Earth's crust, blasting surface rocks
07:20out into space.
07:23These surface rocks contain only a small amount of iron.
07:28The atmosphere around the molten planet is filled with rock vapor.
07:33Earth's gravity pulls back most of the debris, but some is catapulted into space, although
07:39it cannot escape completely.
07:42Instead, it is trapped by the Earth's gravity, forming a ring of red-hot dust and rock around
07:48the planet.
07:54In a process called accretion, the circling dust and rocks collide and fuse with other
07:59fragments to create larger blocks.
08:05We can represent this process by olive oil and water.
08:08The water here represents the space around the Earth, and the olive oil is the debris
08:13thrown around the Earth by this giant impact.
08:16And each little droplet that we pour in here represents a given chunk of matter thrown
08:22up, blasted off the Earth.
08:25We're going to stir this around, indicating the way the debris is being moved around the
08:30Earth.
08:32But when Taylor stops stirring, the drops bump into each other and clump together as
08:38bigger droplets.
08:40And that process of small things bumping into each other, becoming larger, is called accretion,
08:45and that's how the Moon formed around the Earth, that's how the Earth formed around
08:48the Sun.
08:50As the debris clumps together, its combined gravity becomes strong enough to attract even
08:56more debris.
08:58This chain reaction doesn't stop until the billions of fragments of vaporized rock have
09:03gathered into one red-hot ball of matter.
09:08In less than 100 years, this cools into a solid lump of rock, one-fiftieth the volume
09:15of Earth.
09:16It becomes the Moon.
09:21When the Moon forms, it is just 17,000 miles away, but it doesn't stay as close as that.
09:28This violent birth sets it spinning away from us on a journey that will last for ten
09:33billion years.
09:40Absolute proof that the Moon is moving away comes in 1969, when astronauts leave an 18-inch
09:46reflective plate on the Moon's surface.
09:49By bouncing lasers off this plate, scientists can pinpoint the Moon's distance from Earth
09:55to within an inch.
09:57Such calculations reveal that the Moon is moving away from Earth at a rate of about
10:011.5 inches per year.
10:04So why is the Moon on the move?
10:09In the 1990s, supercomputers gave scientists a more accurate picture of what happened 4.5
10:17billion years ago.
10:19Computer models of the creation impact reveal that the collision of Theia and Earth is a
10:24glancing blow.
10:27It imparts a rotational force to the Earth.
10:30This rotation gives Earth its days and nights.
10:35But the huge power of the collision sets the Earth spinning far faster than the Moon, which
10:40orbits around it.
10:43In these early days, Earth spins once every six hours, four times faster than today, whereas
10:50the Moon takes 20 days to complete one orbit.
10:54So the Moon orbits more slowly than the Earth spins.
10:59However, the early Moon is 15 times closer than today, which makes the effect of its
11:06gravity so strong that, as this graphic demonstrates, it pulls up a bulge on the Earth's surface
11:13directly below it.
11:18This bulge moves like a tide across the Earth's surface, with its own gravity tugging on the
11:24Moon.
11:27Because the Earth spins faster than its satellite, the bulge is always ahead of the Moon.
11:33So it constantly pulls the Moon forward, causing it to accelerate.
11:39Any object that travels in a circular motion will move outwards as it accelerates, much
11:45like a hammer being thrown in the Olympics.
11:50As the Moon accelerates in its orbit, it starts to spiral away from Earth.
11:56It's a journey that will continue for billions of years.
12:01At the time of its birth, the Moon orbits Earth 15 times more closely than today.
12:07But this close proximity puts the Moon in great jeopardy.
12:12It faces a bombardment by thousands of asteroids, which will destroy 80% of its surface.
12:25It is now 4 billion years ago, a time the scientists call 4 Giga Years Ago, or GYA.
12:35The Moon now orbits 86,000 miles away, still three times closer to the Earth than it is
12:41today.
12:45From our planet, the Moon dwarfs everything in the sky.
12:53During this early period of its life, the Moon has its most profound effects on Earth.
13:00The massive collision that creates the Moon is so powerful that it knocks the Earth off
13:06balance onto an axis of 23.5 degrees.
13:16It's this tilt that gives us our spring, summer, fall, and winter.
13:24If we spun on a vertical axis, like the planet Mercury, seasons would not exist.
13:32Anywhere would receive 12 hours of light and 12 hours of darkness.
13:38The poles would be entombed in an eternal freezing twilight, while the equator would
13:45bake in endless heat.
13:49But the Moon does more than merely produce this tilt.
13:52It also maintains it.
13:55The strong gravitational pull of our young Moon acts as a global gyroscope stabilizing
14:01the Earth's axis.
14:03Astrobiologist Lynn Rothschild explains.
14:09The reason we have this obliquity that holds steady is because the Moon helps to stabilize
14:15the obliquity of the Earth.
14:16If we had no Moon, we would end up with what the astronomers call a chaotic obliquity.
14:21We'd have quite a big shift and fairly low time scales.
14:27Without our global stabilizer, our axis could vary between 0 and 90 degrees.
14:34This would alter the distribution of sunlight across the surface of the planet, devastating
14:39our finely balanced weather systems.
14:43Climate patterns would go berserk.
14:46The tropics could find themselves frozen under ice, and Antarctica transformed into a vast
14:53desert.
14:55But luckily, the Moon saves us from such disasters, and allows life to exist.
15:04It turns out that it may have had a really profound influence on how life has originated
15:09and evolved on the Earth.
15:11In fact, you might almost be able to argue that we wouldn't be here today filming this
15:16if the Moon weren't up in the sky.
15:21Not all planets in our solar system are so lucky.
15:25Ours has two moons, but they are too small to stabilize its tilt.
15:30As a result, the red planet rolls much more than Earth.
15:35Some scientists believe that this is one of the reasons that there is no life there now.
15:42When you look at our Moon today, the first things you notice are the craters.
15:48They tell astrophysicists, such as David Kring, about a distant and violent past.
15:55You can look up from your own backyard and see impact craters on the lunar surface.
15:59There are over 300,000 craters half a mile to over 500 miles in diameter on the lunar
16:06surface.
16:08Most of these craters come from meteorites hitting the Moon.
16:13The largest crater you can see from our planet is the Imbrium Basin.
16:18It is 700 miles across.
16:22Moon craters come in various sizes, but almost all were created at around the same time.
16:41Around 4 billion years ago, a chance alignment of the gas giants Jupiter and Saturn changes
16:47the shape of their orbits.
16:50This creates a slingshot effect, hurling asteroids toward the inner solar system, straight
16:56at Earth and the young Moon.
17:00For millions of years, asteroids bombard the entire inner solar system.
17:09Some of these impact events would have produced impact craters the size of continents or larger.
17:14These type of impact events have the capacity to obliterate any oceans on the surface of
17:20the planet and superheat the atmospheres.
17:23Life as we know it could not persist on the surface of the Earth.
17:27This period of intense bombardment is called the Lunar Cataclysm.
17:33The Earth's gravity makes it worse, pulling meteorites and asteroids directly toward itself.
17:41On its own, the tiny Moon might have escaped with less damage, but it's too close to Earth.
17:50Asteroids heading for impact with Earth hit the Moon instead.
17:54The Moon becomes the first victim of collateral damage.
18:01Most of the craters on the Moon form during the Lunar Cataclysm.
18:0480% of the lunar surface is destroyed.
18:10Molten basalt oozes from fissures and fills impact craters, creating seas of lava.
18:19Over millions of years, these will cool, solidify and turn into maria, or seas, such as the
18:27Sea of Tranquility.
18:30It is the pattern of dark basalt rock that creates the face of the man in the Moon as
18:36we know it today.
18:44David Kring demonstrates exactly what happens to the surface of the Moon when a meteorite
18:49strikes.
18:51He releases a five-pound rock from 50 feet above a sandpit.
18:57On impact, sand is fired upwards into the air.
19:05During the Lunar Cataclysm, some impacts are so big that material fired upwards never
19:11returns to the Moon's surface.
19:15Instead, it is propelled into space, where it is trapped by the gravity of the Earth,
19:24still only 86,000 miles away.
19:28Some of these rocks hurtle toward our planet.
19:33You actually would have seen a huge plume of debris rise up off the lunar surface.
19:38This cloud, in fact, would have enveloped the entire lunar surface.
19:42And out of that cloud, there would have been fragments of rock that pelted the Earth.
19:47They would have streamed through the atmosphere as intense fireballs to land rocky components
19:52on the Earth's surface.
19:55These lunar meteorites are incredibly rare.
19:59This is part of one of only 30 lunar meteorites ever found.
20:05So this is a sample that fell in Africa.
20:09Analyses of samples like this tell us that there was a cataclysmic spike in the number
20:16of impact events that affected the Moon 3.9 to 4 billion years ago.
20:22Lunar meteorites contain a record of the geological history of the inner solar system, as it was
20:28around 4 billion years ago.
20:33These rocks are older than the oldest rocks on Earth.
20:38The existence of lunar meteorites on Earth started scientists wondering if rocks can
20:43be catapulted from the Moon to Earth, could rocks from the Earth also reach the Moon?
20:51And if such Earth meteorites could be found, might they hold fascinating clues to what
20:57was happening on Earth billions of years ago?
21:03To blast anything free from Earth's strong gravity requires immense force, far more power
21:13than it takes to launch a lunar meteorite off the surface of the Moon.
21:18For example, the space shuttle uses 15 million horsepower to escape from Earth's gravity.
21:27The lunar module needed just 6,300 horsepower to lift off from the Moon.
21:40Just how big an impact would it take to blast debris off of the Earth?
21:55Award-winning astrophysicist Guillermo Gonzalez from Iowa State University has figured out
22:00the answer to that question.
22:05The crater in northern Arizona, Meteor Crater, even that, which is really big when you go
22:10right up to it, wasn't large enough to catapult any significant amount of material beyond
22:15Earth's atmosphere.
22:17But when you're talking about, say, the crater that killed the dinosaurs in Mexico, now that
22:22one was probably big enough to start launching some at least small amount of material beyond
22:27the Earth and have some of it land on the Moon.
22:30Impacts on Earth during the lunar cataclysm are far bigger than the dinosaur extinction
22:35event.
22:37They impact with such power that they punch holes in the Earth's atmosphere.
22:43Rocks and debris thrown skywards escape through these holes.
22:47Once in space, some of the debris is vacuumed up by the Moon, orbiting just 86,000 miles
22:53away.
22:54And it eventually makes its way to the Moon, where it lands.
22:58And then when it lands on the Moon, of course, it could be further broken up into smaller
23:02pieces depending on how fast it hits the surface.
23:07Landing on the lunar surface, they remain perfectly preserved in the vacuum of space.
23:13The early Earth, unfortunately, erased its early history.
23:18But it left a record of it, at least a partial record of itself, on the Moon.
23:22And if we can find some fossils or at least remnants of early life in these Earth rocks
23:27on the Moon, that can help us answer these difficult questions about the origin of life.
23:32Gonzalez believes that more than 1,000 pounds of Earth rock could be spread over every square
23:39mile of the Moon's surface.
23:43It's the only place in the solar system that we can go to, to learn about the origin of
23:47life because once the Earth rocks get to the Moon, they're preserved there in a pristine
23:52form.
23:53There's no water cycle on the Moon.
23:54There's no more active geology.
23:57And they get buried relatively quickly from the material, from other impacts on the Moon.
24:02And so they're preserved from the solar wind and other things as well.
24:07So far, no Earth rocks have been found on the Moon.
24:12Gonzalez will have to wait until the next Moon mission, in the hope that these priceless
24:17rocks may then be discovered.
24:22The first half billion years of the Moon's journey from Earth has been a violent one.
24:28Over the next billion years, the Moon continues its escape from Earth and out into space.
24:35Its passage changes the face of our planet beyond all recognition.
24:40The power of its gravity creates tides thousands of feet high, stirring up the oceans of the
24:46Earth.
24:47This creates the conditions for complex chemical compounds to form.
24:52The Moon is aiding the creation of life on Earth.
25:00Three billion years ago, the Moon is still escaping from the Earth, and it now orbits
25:07almost 200,000 miles away.
25:10The effect of its gravity is weaker, but it still has the power to radically change our
25:16planet.
25:17For now, the Earth has water and oceans, and the Moon is stirring things up.
25:26It's too far away to have a dramatic effect on the rocks of the Earth, but the Moon is
25:31affecting the oceans.
25:34As the Moon passes overhead, its gravity creates tides in the water.
25:40But these are not like the tides of today.
25:44These are thousands of feet high.
25:55Astronomer Neil Cummins studies how the early Moon affected the tides.
26:00When the Moon first formed, the tides were something like a thousand times higher than
26:05they are today.
26:06They would have gone inland as a wall of water, 10,000 feet high, as high as a huge mountain.
26:13It probably would have covered hundreds of miles.
26:16And then they would come back, scouring the land, taking debris from the surface of the
26:21Earth into the oceans.
26:24The material sucked into the seas contains minerals and nutrients.
26:30The tides created by the Moon churn these into the most crucial cocktail in the history
26:35of Earth, the primordial soup.
26:39Different combinations of minerals are bound together and torn apart.
26:45It's in this violent melting pot that the right combination of minerals is forged into
26:51life.
26:56Cummins believes that the spark of life might never have occurred without the Moon's power
27:01to churn up the primordial soup.
27:03The Moon created those tremendously high tides back when it first formed that allowed
27:09the oceans to fill with minerals, that allowed life to evolve, that allowed us to be here.
27:16The tides may have even helped the first DNA to evolve.
27:21Some scientists believe that the changes in chemical concentrations when the tides go
27:26in and out caused the DNA to split and replicate.
27:32The enormous Moon-induced tides have a further vital role to play in the history of the Earth.
27:38They help the whole atmosphere of the planet to calm down and become a more hospitable
27:44place in which more complex life can evolve.
27:49In our look back to three billion years ago, the Earth is a very different place.
27:54The impact that creates the Moon sets the Earth spinning faster.
28:01It spins so much faster than it does now that a day lasts just six hours.
28:09This high-speed spin has devastating effects right around the Earth.
28:15The rotation of our planet is one of the most influential factors determining global climate.
28:21The spin of the planet creates winds and vortices in the atmosphere.
28:27The faster the spin, the faster and more violent the winds.
28:35Billions of years ago, when our planet rotated four times faster, the atmosphere whips over the land.
28:44When a hurricane occurs today, 100-mile-an-hour winds, trees are blown over, houses lose their
28:52roofs, a tremendous amount of flooding.
28:56But in a day or two, it's gone.
28:58Things settle back to normal, people get on with their lives.
29:02Imagine if we lived on a world in which those kinds of winds were continuous.
29:09This is the climate of our fast-spinning early Earth, a place with constant hurricane-force
29:15winds and giant 10,000-foot tides.
29:20This is far too hostile a climate for life to evolve into more complex forms.
29:26But the devastating tides that the Moon is creating begin to pacify the hellish climate.
29:34The tides affect the speed of rotation of our planet, eventually lengthening a day from
29:40six to 24 hours.
29:47As the Earth's rotation slows, the atmosphere ceases to whip around the globe.
29:55Hurricane-strength winds are no longer the norm, and more complex lifeforms evolve in
30:02the relative peace and calm of our planet.
30:06I really think that we owe the Moon our existence today.
30:11Without it, the world would have evolved differently, and as a result, we would have evolved differently
30:17and we would not be the creatures we are.
30:21The power of the nearby Moon has dramatically reshaped our planet.
30:26Over the next three billion years, the Moon continues its journey out into space.
30:32The Moon's influence has waned, but hasn't disappeared.
30:38Some scientists believe it causes earthquakes and volcanic eruptions, while many laymen
30:44still believe that the full Moon affects our human behavior in bizarre and inexplicable
30:51ways.
30:55Today the Moon orbits Earth, one quarter of a million miles away.
31:01It's 15 times further from Earth than when it first formed.
31:05It appears as a distant and mystical object in the sky, and its gravitational pull is
31:12far weaker than it used to be.
31:17The Moon's gravity is now so small that it exerts the same upwards pull as a pea held
31:24about 20 inches above your head.
31:27But some people still believe that even this weak power from the Moon affects human behavior.
31:35The Moon's 29-day orbit around the Earth is called the lunar cycle.
31:40During the lunar cycle, the appearance of the Moon changes because it is constantly
31:46moving relative to the Sun and Earth.
31:52The full Moon has long been associated with mystery, aggression, and horror.
32:05Studies show that the behavior of some animals changes during the lunar cycle.
32:10Some creatures' whole breeding cycle is dictated by the Moon.
32:16Scientists have investigated the link between predation and the full Moon.
32:22Researchers think that the increased moonlight helps some nocturnal hunters track and kill
32:26their prey, although the idea that wolves howl more often on a full Moon is nothing
32:33more than a myth.
32:40Yet, if some mammals do become more active at full Moon, might this aggressive lunar
32:46trait extend to humans?
33:00The streets of San Francisco.
33:04Officers Healy and Mahoney of the San Francisco Police Department gear up for another night
33:09patrolling the town.
33:13They have been policing the tough Tenderloin District for the past 10 years.
33:18But this is no ordinary night.
33:21It's a full Moon.
33:23And on a full Moon, things definitely feel a bit hotter.
33:27I think some of the clientele we deal with, they think it's a full Moon every day, I think,
33:36but there's a noticeable difference.
33:44You could pretty much ask anybody who works in service jobs like police, fire, paramedics,
33:55hospital workers, they'll all tell you that during the times of the full Moon, business
34:02just goes up.
34:07But is there any scientific evidence of human behavior being affected by the Moon?
34:13In 1976, the American Journal of Psychology studied 34,318 crimes and found they occurred
34:22more frequently at full Moon.
34:25A year later, researchers studying 18,495 psychiatric patients found that hospital admissions
34:33peaked during a new Moon.
34:36However, a series of more recent studies reveals no link between human behavior and the lunar
34:42cycle.
34:47And yet many people still believe in the power of the full Moon, possibly because of horror
34:52movies and folklore.
34:55For generations, we have been led to believe that murder, death, and even mythical creatures
35:01such as werewolves are linked to the full Moon.
35:05It's not surprising that over time, we start to believe the link is true.
35:18And the myth of the full Moon is kept alive.
35:24The effects of the Moon on humans may be minimal, but some scientists believe that its gravity
35:29still exerts a major influence on the planet itself.
35:36It's not only the Moon's appearance that alters with the lunar cycle.
35:40Its gravitational pull varies as well.
35:45At new Moon, when the Sun and Moon are aligned, their combined gravity tugs even more than
35:51usual on the Earth.
35:53As the Moon makes its way around the Earth, it pulls us in different directions.
35:59When there is a full Moon, the Sun and Moon pull in opposite directions, in a kind of
36:04astronomical tug-of-war.
36:09For most of the lunar cycle, there is no danger for Earth.
36:13But when the Sun and Moon are aligned, their combined gravity creates the maximum stress
36:19on the Earth's crust.
36:23Some scientists suggest that this can trigger devastating natural phenomena.
36:35Volcanologists Steve and Donna O'Meara use this cycle to help them predict eruptions.
36:42While other scientists check sulfur levels and study seismographic data to predict eruptions,
36:48Steve and Donna plot the position of the Moon, which they believe has the power to trigger
36:53eruptions at certain points in its orbit.
36:58The O'Mearas believe that in the complicated cycle of tugs and pulls from the Sun and Moon,
37:04increased stress can distort molten rock under the Earth.
37:11At the crust's most unstable points, where volcanoes form, the pressure sometimes becomes
37:17too much and triggers an eruption.
37:28The O'Meara's Eureka moment comes in 1996, on an expedition to an erupting volcano called
37:35Arenal in Costa Rica.
37:37Well, the coolest thing is that all volcanoes are different.
37:41They're just like people.
37:42They have different personalities.
37:43I mean, obviously, there's different types of scientific volcanoes.
37:47This is the Shield Volcano, which has very fluid eruptions.
37:50Stratovolcanoes have huge eruptions.
37:53In volcanoes, we've actually gotten to know some, and like Arenal Volcano, we call it
37:58the Brat, because it's just always...
38:02During their two-week expedition, Arenal lives up to its nickname, erupting 15 times.
38:08They realize that the biggest eruptions occur whenever the Moon is directly overhead.
38:15By tracking the Moon's position over Arenal, the O'Meara's predict eruptions with an accuracy
38:20of 80 percent, a pinpoint accuracy unparalleled in the world of volcanology.
38:27And one of them, we, in fact, woke the villagers and told them that, get prepared, there's
38:32going to be an eruption at, you know, 1230, and bang, 1230, the thing erupted right on
38:38schedule.
38:39Since 1996, the O'Mearas claim to have used the Moon to correctly predict eruptions all
38:46around the world.
38:48Either I have to be the luckiest person on Earth, or the Moon is affecting volcanic eruptions.
38:54But the Moon may trigger natural disasters on an even bigger scale than volcanoes.
39:00One scientist now believes the Moon may have caused two of the worst natural disasters
39:06of recent years, the October 2005 earthquake in Pakistan, and the 2004 Asian tsunami.
39:24Today, the Moon is still on its journey edging away from Earth at 1.5 inches per year.
39:33Even from a quarter of a million miles out in space, its gravitational pull can still
39:39affect our planet.
39:40It is suggested that the Moon can trigger volcanoes, but geologist James Birkeland argues
39:47that it has a far more destructive role.
39:51He believes that the Moon triggers earthquakes, quakes that kill many thousands of people.
40:021994, and Birkeland travels to Peru to witness that rare moment when the Sun and Moon perfectly
40:12line up, creating a solar eclipse.
40:16In Peru, a large earthquake is called a terremoto, and we saw this great eclipse.
40:23And the Peruvian guide said, I am so glad you were able to see our eclipse.
40:28We in Peru have a tradition.
40:31We watch the eclipse, and then we wait for the earthquake.
40:37This ancient Peruvian belief that solar eclipses are involved with triggering terremoto, or
40:44earthquakes, supports something Birkeland has been investigating for the past three
40:48decades.
40:49They have known what I've known for 50 years almost, that the lining up of the Sun, Moon,
40:56and Earth often can trigger quakes.
41:00The Earth's crust is made up of seven tectonic plates that bump and grind against each other,
41:06creating a series of fault lines.
41:09At these points, the opposing plates scrape against each other.
41:13Sometimes slipping or pushing upwards.
41:17This sudden movement causes earthquakes.
41:23Birkeland thinks that the relative position of the Moon and Sun above these fault lines
41:28is critical in the triggering of earthquakes.
41:32When I saw the ocean tides due to the passage of the Moon, then it occurred to me that perhaps
41:40it might loosen up the fault lines and sort of lubricate the faults and make them easier
41:44to slip.
41:47He monitors the location of the Sun and the Moon during the lunar cycle as they pass over
41:52these danger zones.
41:55He also factors in how close the Moon is to Earth, since the Moon's orbit isn't a perfect
42:00circle.
42:01It's elliptical.
42:03The nearest point of the Moon's orbit is called perigee, and its furthest is called apogee.
42:12At perigee, the Moon's pull on the Earth is 20 percent stronger than at apogee.
42:18Now the Earth is here, and the Moon travels around the Earth in a very elliptical orbit.
42:26It's exaggerated here, but when it's at its near point, what we call a perigee, it's only
42:33about 221,000 miles away from the Earth.
42:36When the Moon is closed, its effect on our tides is far greater than it is over here
42:41at the far point, at apogee, 253,000 miles away, just two weeks later.
42:49By combining all this information, Birkeland calculates how much pressure the Moon is putting
42:54on certain fault lines around the world as it passes overhead.
42:59He suggests that a new Moon at perigee can actually cause unstable fault lines to slip.
43:07This technique has allowed him to predict several earthquakes in the past decade.
43:24But his theories are controversial.
43:27In 1989, Birkeland was suspended from his job as county geologist for Santa Clara, California,
43:35until he promised to stop making predictions that caused mass panic.
43:41Other scientists doubt that there is a link between the Moon and earthquakes, but Birkeland
43:46claims that some of his predictions have proved to be correct.
43:56October 1989.
43:59Birkeland warns the city of San Francisco that a big quake is about to strike.
44:07A few days after his alert, during the World Series, Birkeland's tragic prediction comes
44:14true.
44:18When the World Series quake hit, I was on the seventh floor of the county building,
44:22and boom, the P wave hit.
44:25And for two seconds I was elated, I got my quake!
44:28And then I didn't want any part of it because I was being rocked back and forth, I held
44:33on to the counter, it was frightening.
44:36The 6.9 magnitude quake causes $6 billion of damage and claims 63 lives.
44:45It's the biggest earthquake to hit San Francisco in 80 years.
44:51A quake of 6.5 to 7 from the Bay Area when we hadn't had such a quake since the 1906
44:55quake is a pretty good call.
45:00Birkeland's ideas are radical, and the exact nature of the Moon's influence on earthquakes
45:04is not well understood.
45:06However, in 2004, Birkeland predicts that a huge earthquake will occur around the time
45:14of the full Moon, just after Christmas.
45:18The earthquake that triggers the Indian Ocean Tsunami duly occurs on December 26th, 2004,
45:25at a full Moon.
45:30In 2005, Birkeland predicts a 7.0 earthquake, and within weeks of his prediction, a 7.6
45:37magnitude earthquake hits Pakistan, just after a solar eclipse over the country.
45:45Could this be a demonstration of the Moon influencing our planet, even though that influence
45:51is waning?
45:53Today, the Moon and Sun appear exactly the same size in the sky, meaning that the Moon
46:01covers the Sun during a solar eclipse.
46:05But let's look into the distant future.
46:09Half a billion years from now, and the Moon is so far from Earth that eclipses are a thing
46:16of the past.
46:18Less than two billion years hence.
46:22With the Moon no longer holding the Earth on its axis, the planet rocks back and forth,
46:28the weather goes wild, and life on Earth is threatened.
46:36Billions of years into the future, the Moon reaches the end of its journey away from the
46:41Earth, its orbit stabilizes.
46:46In five billion years, the Sun expands as it nears the end of its life.
46:52The Earth and Moon, so inextricably linked in life, are together in death, engulfed side
47:00by side by the awesome heat of our dying Sun.