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15 INSANE Facts about Earth
Transcript
00:00Discover the wonders of our planet, we're counting down the 15 most astonishing facts
00:05about the Earth.
00:0615.
00:07The Earth May Have Had Two Moons According to some reports, Earth may have
00:10had two moons in the distant past.
00:13The theory goes that a tiny second moon once orbited Earth before catastrophically slamming
00:18into the other one.
00:20This would explain why the dark side of the moon looks so different than the side we see
00:23every night, as the dark side may have been pancaked by this smaller moon before it either
00:28broke itself to bits or spun out of the Earth's orbit.
00:3214.
00:34Days Are Getting Longer When the Earth was formed about 4.6 billion
00:38years ago, a day would have been roughly six hours long.
00:42Now, the number is 24, and every century that number increases by about 1.7 milliseconds.
00:48This could be a result of climate change, according to Professor Duncan Agnew from the
00:53Scripps Institution of Oceanography.
00:56As polar ice melts, the water spreads out over the whole ocean, causing the same effect
01:00as the skaters spreading their arms out.
01:03The Earth slows down.
01:0513.
01:07The Earth Used To Be Purple While this one's still up for debate, there
01:11are some scientists who believe that the Earth was once purple.
01:15The basic idea behind this claim is that while today's plants are green thanks to chlorophyll,
01:20in the past, ancient plants may have had a different molecule to harness the sun's rays.
01:26Known as retinol, it would have given organisms a violet hue.
01:30However, because chlorophyll was more efficient, it likely beat out retinol, giving the world
01:35the green color it's got today.
01:36Yeah, I think I prefer green.
01:3912.
01:40The Earth's Largest Structure Pause this video for a moment and guess,
01:45what's the largest structure on the planet?
01:47Most likely, you guessed the Burj Khalifa in Dubai, which is the world's tallest building.
01:52Or the Tesla Gigafactory, which is the world's largest building by surface area.
01:57Unfortunately, you're not even close.
01:59That's because the world record belongs to Australia's Great Barrier Reef.
02:03This massive coral structure is a whopping 348,000 square kilometers, making it many
02:09times larger than any human-built structure on the planet.
02:1411.
02:15The Third Pole Believe it or not, the Earth has three poles.
02:20Well, kind of.
02:22Well the North and the South Pole are the Earth's first two poles.
02:25In some ways, the Tibetan Plateau acts as a third.
02:28It's located at the intersection of South Central and East Asia.
02:32It's a land of large glaciers, permafrost, and heavy snow that feeds the Ganges, Indus,
02:38Mekong, Yangtze, and Yellow Rivers.
02:40This vast amount of water, ice, and mountain range affects the atmospheric circulation
02:45and drives weather patterns across the continent.
02:48The effect is so strong that it has many of the capabilities of our North and South
02:52Poles.
02:5410.
02:55The Earth Isn't Round Before the conspiracy nuts get too excited,
02:59I'm not saying that the Earth is flat.
03:01However, it's far from a perfect sphere.
03:05While it may look this way from a distance, the reality is that the Earth's shape is
03:09constantly changing.
03:11The best word we have to describe this shape is an ellipsoid, that is to say a deformed,
03:16not perfectly symmetrical sphere.
03:18However, even this strange shape doesn't perfectly explain the Earth's strange form.
03:22Our planet's diameter bulges at the equator and it flattens a bit at the poles due to
03:27the centrifugal forces created by the Earth's constant rotation.
03:31As explained by geologist Vic Baker of the University of Arizona, quote, instead of Earth
03:35being like a spinning top made of steel, it has a bit of plasticity that allows the shape
03:40to deform very slightly.
03:42The effect would be similar to spinning a bit of silly putty, though Earth's plasticity
03:46is much, much less than that of the silicone plastic clay so familiar to children, end
03:52quote.
03:53Additionally, mountains rising to heights of about 9,100 meters and ocean trenches diving
03:57down to nearly 11,000 meters below sea level further distort the Earth's shape.
04:02Even at sea level, things aren't perfect.
04:04After all, sea level is irregularly shaped, as slight variations in the Earth's gravity
04:09cause permanent hills and valleys in the ocean's surface that often measure in at over 90 meters
04:14in height.
04:15In addition to these stable oddities, the Earth also has changes that are periodic or
04:20random in nature.
04:22For example, tides affect both the ocean and the crust on a daily basis, while the drift
04:26of tectonic plates and rebound of the crust after a heavy sheet of ice is melted is slow
04:31and gradual.
04:33From time to time, earthquakes, volcanic eruptions, and meteor strikes also hit our planet, changing
04:38its shape in ways that are unpredictable.
04:40Interestingly, America's National Geodetic Survey has made it its mission to measure
04:45and monitor the ever-changing size and shape of the Earth.
04:49This in turn not only provides us with a constant idea of the Earth's form, but it also allows
04:53us to plan our structures, shipping routes, and building strategies accordingly.
04:589.
04:59The Earth Has an End Date Much like a carton of milk or a bag of avocados,
05:05the Earth has a best-before date.
05:07That is to say, there will come a time when the Earth will be uninhabitable, and in some
05:11ways, that date is in our control.
05:14The rather obvious within-our-control date would be brought upon by climate change.
05:19It's now indisputable that the Earth is warming faster than it should be through natural means.
05:25Without going through points that you've probably heard before, the bottom line is that this
05:27will increase natural disasters, flood coastal cities, and make it near impossible to farm
05:32in most areas of the world, among many other things.
05:36In time, this would make at least many parts of the Earth unlivable, with the effects being
05:40especially bad in poorer areas.
05:43While those in rich countries at high altitudes will probably be better off, if left unchecked,
05:48climate change will lead to end-of-life, global economies, and luxuries we enjoy.
05:53However, the reality is that while climate change will dramatically change human life,
05:58it likely won't lead to the planet's end.
06:00This doesn't mean that we're completely in the clear, though.
06:03That's because it's believed that the Earth will become unlivable for most organisms in
06:07about 1.3 billion years due to the sun's natural evolution.
06:12That's because at this point, sustained hot and humid conditions will make the planet
06:16unlivable, and in about 2 billion years, the oceans will likely evaporate, and in time,
06:21our atmosphere will eventually disappear.
06:24While extremophiles, that is to say, small organisms that live in volcanic vents deep
06:28under the sea, might be able to eke it out, we humans won't stand a chance.
06:34However, even those extremophiles will eventually meet their demise.
06:37That's because in about 4.5 billion years, the sun will become a large red giant that
06:42will engulf the Earth, completely destroying everything that's still left.
06:47And if that wasn't bad enough, there's still a chance that other occurrences such as nuclear
06:51wars or even asteroids hitting our planet could also end human life.
06:56So therefore, the harsh reality is that while Earth may have an end date that's billions
07:00of years away, we're probably going to be off this planet far sooner than that.
07:058.
07:06The Earth's Core is as Hot as the Surface of the Sun
07:10When you think of the sun, you probably think about a hot ball that would immediately burn
07:14up anything that got too close.
07:15However, despite being so insanely hot, it turns out that our planet's core packs just
07:21as much heat.
07:22That's because it turns out that both the Earth's core and the surface of the sun are
07:26both a little over 6,000 degrees Celsius.
07:29This leaves us with an important question.
07:31How can Earth's core be so hot without simply burning up the planet?
07:35Well, the best way to think of the Earth is like an onion.
07:38Every time you go down a certain amount of meters, you reach another layer.
07:42Starting from the top down, there's the crust, which includes the surface that we walk on.
07:46Then farther down, the mantle, which is mostly solid rock.
07:50Then even deeper, the outer core, made of liquid iron.
07:53And finally, the inner core, made of solid iron, probably.
07:57And with a radius that's about 70% the size of the moon's.
08:00The deeper you dive, the hotter it gets, until you reach the hottest spots at the center.
08:06Yet because of the existence of these layers, this inner heat is not able to penetrate all
08:11the way up to the planet's surface, saving us from our destruction.
08:14The Earth seemed to have picked up all this heat about 4.5 billion years ago.
08:18The first bit was inherited during our planet's formation.
08:21You see, the Earth was made from the solar nebula.
08:24This was a giant gassy cloud, and when the planets were forming, there were endless collisions
08:29and mergers between different rocks.
08:31This movement created enormous amounts of heat, and some of that heat was locked inside
08:36the Earth.
08:37The other heat source was the decay of radioactive isotopes.
08:41Distributed across the Earth, these tend to release energy underground, and along with
08:45the hot core and mantle, they provide the heat necessary to drive the motion of the
08:49Earth's plates.
08:50Now here's the crazy part.
08:51If the Earth's core had no heat, there would be no plate movement, and therefore, no life.
08:57That's because without plates continuously moving, the Earth would have had a weaker
09:00atmosphere and would have been far colder than it is today.
09:04This would have in turn made human life impossible.
09:07So therefore, we owe a lot to our planet's super hot core.
09:12Moving on to number 7.
09:14The Moon is Drifting Away From Us 300 years ago, the famous English astronomer
09:19Edmund Halley hypothesized that the Moon was moving away from us after studying records
09:24of ancient eclipses.
09:26In the 1970s, that hypothesis was confirmed.
09:29You see, during the Apollo missions, NASA put mirrors on the Moon.
09:34Scientists then bounced laser beams off them and used the measurements to determine that
09:37the Moon was indeed moving away from the Earth at a rate of 3.8 centimeters per year.
09:43For reference, that's roughly the rate at which fingernails grow.
09:48Making this change a small yet calculable one.
09:51This can be explained by the effect of the Moon's gravity on the rotating Earth.
09:55The Moon is responsible for the Earth's tides, and as these are raised, they cause drag that
10:00slows the Earth's spin rate down.
10:02This resulting loss of angular momentum is compensated by the Moon speeding up, and this
10:07in turn causes it to move further away.
10:10As put by astrophysicist Madeline Broome of the University of California, quote, since
10:14the Earth and the Moon are a part of the same gravitationally interacting system, total
10:18angular momentum must be conserved between the two.
10:22As the Earth's spin slows down thanks to tidal drag, in order for angular momentum
10:26to be conserved, something has to increase the angular momentum of this system, end quote.
10:32Well, the Moon moving further away increases that angular momentum.
10:35However, there is a small mathematical problem with this model.
10:39At the current rate of the recession, the calculations showed that the Moon must have
10:42separated from the Earth about 1.5 billion years ago, which is far more recently than
10:47the geological evidence suggests.
10:50While this may seem fatal to the entire theory, astronomers have an explanation.
10:54They argue that the recession rate must have been slower in the past.
10:59This is because phenomena like continental drift, which altered the size and depth of
11:03the oceans, must have in turn altered the amount of tidal drag.
11:07When you take this into account, this pushes the date of the separation back by several
11:11billion years, thereby putting the standard hypothesis in line with the geological evidence.
11:16Well, of course, this all leaves us with an interesting question.
11:19Will the Earth ever lose its Moon?
11:22The short answer is no.
11:24In fact, calculations of the evolving Earth-Moon system tell us that in about 15 billion years,
11:29the Moon will actually stop moving away from the Earth.
11:32However, since the Earth will likely be engulfed by the Sun in the next 4 billion, we're never
11:37going to get to see that in action.
11:396.
11:40The Ocean Is Filled With Gold While the world's oceans may look like a long
11:45expanse of water, the reality is that they're filled with minerals, with the most desirable
11:51among them being gold.
11:53Estimates as to how much gold exists in our ocean varies.
11:56However, there's believed to be about 1 gram of gold for every 100 million tons of ocean
12:01water in the Atlantic and North Pacific.
12:03However, since all this gold is located in tiny concentrations within the water, extracting
12:08it would be difficult.
12:09Yet that doesn't mean that it wouldn't be impossible, and to date, the most effective
12:13method would likely be gold dredging.
12:16This process involves using a vessel with a giant scooper to remove sediment from the
12:20ocean floor.
12:21The sediment is then processed to extract the gold.
12:24But this process is not only expensive, it's also harmful to the environment, as the dredging
12:29process can damage marine habitats and release toxins into the water.
12:34There are also other methods of extracting gold from the ocean, such as using magnetic
12:38nanoparticles or bacteria.
12:40However, these methods are still experimental, and their feasibility is yet to be established.
12:45That doesn't mean that gold couldn't be extracted from the Earth's oceans in another way.
12:50That's because much like the oil reserves reached by oil rigs, there are also gold reserves
12:54buried underwater.
12:56The only problem is, these deposits are often multiple kilometers below the ocean's surface
13:00and encased in rock.
13:02This makes mining pretty difficult, and with current technology and at current prices,
13:07it's impossible to extract the gold down there while still turning a profit.
13:11Yet given the fact that there may be as much as 20 million tons of gold in total spread
13:15across the Earth's oceans, it's likely that at some point, some sort of ocean gold extraction
13:20may be attempted.
13:21Oh, by the way, the ocean isn't the only place on Earth with unreachable gold.
13:26According to scientists, the Earth's core is believed to contain vast amounts of gold,
13:30by some estimates, as much as 1.5 quadrillion tons.
13:35However, because it's located about 2,900 kilometers below the surface of the Earth,
13:39reaching it today would be impossible.
13:42So while the Earth may have a lot of hidden gold, the sad reality is that you won't be
13:46getting your hands on it anytime soon.
13:495.
13:50The Moon is the Earth's Child While there are multiple theories about how
13:55the Moon was formed, the most widely accepted is the Giant Impact Theory.
14:01The basic idea behind it is that the Moon formed during a collision between the Earth
14:05and another smaller planet about the size of Mars.
14:08The debris from this impact collected in orbit around the Earth to form the Moon, while the
14:14impact on Earth was gradually smoothed away, allowing the Earth to maintain its roughly
14:18spherical shape.
14:20This theory is supported by the evidence brought back from NASA's Apollo program.
14:24In total, these missions brought back over a third of a ton of rock and soil from the
14:28Moon.
14:29When analyzed, researchers found that the Earth and Moon have some remarkable chemical
14:33and isotopic similarities.
14:34Now, if the Moon had been created elsewhere and was simply captured by Earth's gravity,
14:39its composition would have been very different from that of Earth.
14:42Instead, the fact that the composition of the Earth and Moon are very similar suggests
14:46there is a linked history.
14:47However, this doesn't mean that the debate is fully settled.
14:50After all, while the composition is similar, it isn't the same.
14:53That's because the minerals on the Moon contain less water than those of similar rocks on
14:57Earth.
14:59This has forced scientists to take a long, hard look at the giant impact model, and to
15:02date, the explanation for this difference may lie in the details.
15:06The most common idea now is that when the Earth and the Mars-sized planet collided,
15:11they were two similar yet not identical planets.
15:14While most of the material from the collision melted and fused to form the modern Earth,
15:18a small part of the new mass became the Moon as we know it.
15:22Since this breakaway piece may have contained more of one planet than another, this may
15:26explain the slight differences between the two planets.
15:30To date, scientists have tried to create models that adjust the sizes of the two planets and
15:34the impact angles to get the nearest possible match.
15:37That work is still ongoing, however, it is worth mentioning that there are a few other
15:41explanations for how the Moon formed.
15:43Perhaps the second most common is the capture theory.
15:46This hypothesis suggests that the Moon was a wandering body that formed elsewhere in
15:51the solar system and was captured by the Earth's gravity.
15:54Others instead subscribe to the accretion theory.
15:57This idea proposed that the Moon was created alongside the Earth at the time of the Earth's
16:02formation.
16:03There are some who even subscribe to the fission theory, which posits that at some point the
16:07Earth had been spinning so fast that some material broke away and began to orbit the
16:11planet.
16:12However, extensive debates on the subject in the 1970s and 80s have all but put those
16:17theories to rest, and today, the giant impact theory reigns supreme.
16:234.
16:25Gravity Isn't Uniform Ever since the apple fell on Isaac Newton's
16:29head, the theory of gravity has been progressively developed.
16:32However, the way the force of gravity works isn't the same everywhere on Earth.
16:37That's because depending on where you're standing, the amount of gravity weighing on you will
16:41be quite different.
16:42In order to calculate these differences, we have to look at a few factors.
16:46The first is the latitudinal effect.
16:48You see, the Earth isn't perfectly round.
16:50Rather, it gets flatter the closer you get to the poles, and it bulges out the closer
16:53you get to the equator.
16:55As a result, the distance from the Earth's center to sea level is about 21 kilometers
16:59greater at the equator than it is at the poles.
17:02Now, translated into gravitational terms, you weigh 0.5% more at the poles than you
17:08do at the equator.
17:09The second factor is the rotational effect.
17:11You see, the Earth spins faster at the equator than it does at the poles, and this influences
17:16the strength of the force of gravity.
17:18Altitude also has an effect.
17:20You see, Earth's gravitational pull depends on your distance from its center, so therefore
17:24gravity diminishes with altitude.
17:26For example, if you were 5 kilometers up a mountain, you would weigh 99.84% of what the
17:31scales would say at sea level.
17:34The fourth factor is the force of the tide.
17:36Now, essentially, tides are caused by the pull of the Moon's gravity on the Earth.
17:40Now, this change can in turn affect the amount of gravity you experience.
17:44Finally, the density of certain rock types also has an effect on the force of gravity.
17:50For example, areas with higher subsurface rock density have higher than average gravity.
17:54As such, while mountains increase gravitational density, ocean trenches decrease it.
17:59However, this effect is pretty small, usually it isn't greater than 0.01%.
18:04Now while the first four factors can be compensated for mathematically, it's the local geology
18:09which produces random gravity anomalies.
18:13In order to visualize the impact of these anomalies, most scientists use a gravity anomaly
18:18map named in honor of the 18th century French scientist Pierre Bouguet.
18:22It was he who discovered that a small regional variation in the Earth's gravity field could
18:26be related to the varying density of underground rocks.
18:30The Bouguet gravity maps makes it possible to see how these variations are distributed,
18:34with areas of lower gravitational pull being colored more red and areas with higher gravitational
18:40being colored more blue.
18:42Using such a map, we can see that a country like the US, even state to state differences
18:46are calculable.
18:48For example, if Newton's apple were to have fallen on him in southern Illinois, it would
18:51have weighed a bit more than it would have had in central Indiana.
18:55Of course, these effects are rather minute, in reality they only account for variations
19:00in decimal points, yet despite the effects being small, they can have a noticeable impact.
19:06For example, it can cause the sea to bulge in certain places and throw pendulum clocks
19:11out of sync.
19:12In areas of science where exact precision is of the essence, it's therefore essential
19:17that these variations in gravity are precisely understood.
19:213.
19:22The Earth May Have A Population Limit While the idea of the Earth having a population
19:27limit may seem obvious, exactly what that would look like is something that's one of
19:32the Earth's greatest existential mysteries.
19:34The first real look into this dilemma was recorded by Dutch scientist Antony van Leeuwenhoek
19:39in 1679.
19:41He reasoned that his home country of Holland occupied one part in 13,000 of Earth's habitable
19:47land and so multiplied Holland's population of 1 million people by 13,000 to get a total
19:53capacity of 13 billion people.
19:56Since then, our understanding of how population limits work has advanced quite a bit.
20:01Nowadays, this common concept is the Thomas Malthus idea of carrying capacity, that is,
20:07the maximum number of people who could live on Earth after considering both natural constraints
20:11and human choices.
20:13In context, natural constraints include food scarcity and inhospitable environments, while
20:18human choices include interactions between economics and culture, such as how we produce
20:23and consume goods, as well as birth rates, average lifespans, and migrations.
20:29Another central component to carrying capacity is that it's indefinite, that is to say it
20:33calculates the maximum population that is sustainable indefinitely.
20:37This means that while it is possible for Earth to function beyond its carrying capacity,
20:41this would eventually end in disaster long-term.
20:44Now, what's really interesting about this number is that it's not static.
20:48After all, humans in different geographies produce and consume at different rates, and
20:52how all of this is distributed dramatically affects carrying capacity.
20:57In terms of trying to pinpoint a number, the United Nations Population Division projects
21:01that the world population will reach 10.4 billion people sometime in the 2080s and remain
21:06there until 2100.
21:08However, whether or not that reflects a true maximum is impossible to know right now.
21:13Unsurprisingly, there are a lot of studies that have tried to answer this question, but
21:17going through all of them would be a better fit for a documentary than a YouTube video.
21:21When the United Nations Environment Program looked at all the major ones, they found that
21:26the vast majority of the studies showed that a number is somewhere between 4 and 16 billion
21:31people.
21:32Aside from the fact that our planet has about 8.1 billion people already, this rather low
21:36number is a cause for concern.
21:38However, given that the studies range from anywhere between 2 billion and 1.2 trillion,
21:43it's hard to get a definitive conclusion.
21:45Now, while we may not actually have a fixed carrying capacity, what we do have are methods
21:50to ensure that we never get there anyway.
21:53For example, one study published in the prestigious academic journal Proceedings of the National
21:58Sciences found that if the population of the United States switched to a vegetarian diet,
22:03the land used to grow crops for humans rather than animal feed for meat production would
22:07feed an additional 350 million Americans.
22:11Furthermore, the numbers indicate that places where women have increased access to education
22:15and family planning, they tend to have lower birth rates and smaller family sizes than
22:20in middle and lower-income countries where they may not.
22:23So while we may never know the Earth's true carrying capacity, it's most certainly in
22:28the interest of the humanities to not test the upper boundaries if possible.
22:332.
22:35We're Often Hit By Space Rocks When you think of an asteroid hitting Earth,
22:39you likely think of a massive hunk of rock that wiped out the dinosaurs 66 million years
22:44ago.
22:45However, it turns out that asteroids come in all shapes and sizes, and when looked at
22:49in totality, we deal with these pesky space rocks almost every single day.
22:54First and foremost, it's worth clearing up the difference between asteroids, meteors,
22:58and comets, as these terms are often used interchangeably but don't mean the same thing.
23:03A comet is an object consisting of ice and dust that orbits the sun.
23:08These typically do not hit Earth.
23:10A meteor is a small piece of an asteroid that burns up after entering the Earth's atmosphere.
23:15These tiny guys are pretty common, as about 17,000 of them fall to Earth each year.
23:20However, because they burn up so quickly, they usually reach the Earth's surface as
23:24dust and don't have much of an impact.
23:27Now, asteroids are something entirely different.
23:30Unlike meteors and meteorites, which are small, asteroids are larger space rocks that don't
23:35fully burn when going through the atmosphere.
23:38When they hit the Earth, they have the ability to cause a lot of damage, however exactly
23:42how much damage is relative to their size.
23:45The smallest asteroids that are cause for concern are between 25 and 140 meters in diameter.
23:51These are relatively rare.
23:53On the larger end, those that are more than 100 meters in diameter only hit the Earth
23:57once every 10,000 years or so.
23:59However, when they do touch down, they can cause a lot of local damage.
24:03One recent example happened in 2013 over the Russian Oblast of Chelyabinsk.
24:08After exploding at a height of about 39 kilometers, the 18-meter-wide meteor created a massive
24:13shockwave.
24:15In total, it damaged about 7,000 buildings across six cities and injured about 1,500
24:20people.
24:21However, the most destructive was the so-called Tunguska event happening in Siberia in 1908.
24:27It may have been as much as 100 meters in size.
24:30However, despite being so large, the rock was never recovered and it's believed that
24:34it likely burned up at an altitude between 5 and 10 kilometers.
24:38Now while these types of asteroids are manageable, those that are between 140 meters and a kilometer
24:44in diameter are way more destructive.
24:47These are able to devastate entire regions, causing horrific events such as fires, tsunamis,
24:53and massive changes.
24:54Thankfully, these are pretty rare, they only happen every 10,000 years or so, and none
24:58are believed to have occurred within recorded history.
25:00Yet the most terrifying asteroids of them all are those over a kilometer in diameter.
25:07These types of collisions are globally catastrophic, they have the potential to cause mass extinction.
25:13The most famous example of one was the asteroid that wiped out the dinosaurs, coming in at
25:17between 10 to 15 kilometers in diameter.
25:20It radically changed the Earth's climate.
25:23As far as we know, very few species survived the disaster, however some of those that did
25:27include several types of birds, lizards, turtles, and crocodilians.
25:32But what has survived are remnants of the asteroid.
25:36Located in the Yucatan Peninsula, most of the crater has been covered by hundreds of
25:39meters of limestone or filled in by the waters of the Gulf of Mexico.
25:44However, there are still some areas on Mexico's mainland that are visibly deeper thanks to
25:48this impact.
25:49Well, thankfully, we're not due for a similar event during our lifetimes.
25:53According to NASA's Jet Propulsion Laboratory, there's no currently known significant threat
25:57of impact for the next 100 years or more.
26:01So I guess you can rest easy at night knowing that no world-ending asteroids will be interrupting
26:05your sleep.
26:071.
26:08The Earth's Magnetic Field is Creeping Westward
26:12The Earth's magnetic field is massively important.
26:15After all, it's the shield that protects us from the charged particles streaming from
26:18the sun, and it keeps us from becoming a barren, Mars-like rock.
26:22However, for the past 300 years or so, this magnetic field has slowly drifted westward
26:28at a rate of about 17 kilometers per year.
26:32Scientists have known this for quite a while.
26:34The astronomer Edmund Halley is the first to observe it all the way back in 1692.
26:38However, despite centuries of work on the subject, we don't know exactly why this westward
26:43shift is happening.
26:44For some context, the Earth's magnetic field is created by interactions deep inside the
26:49Earth's core.
26:50While the inner core is presumably solid, the outer core features flowing liquid iron,
26:55which generates current that in turn leads to magnetic fields.
26:59This field changes over time, with certain areas receiving better coverage than others.
27:04However, what's weird is that in the low latitudes of the Western Hemisphere, these
27:08changes are especially obvious.
27:11While these changes are certainly driven by the intense activity in the core, for years
27:14scientists were not sure why these areas were affected more severely.
27:19But a team led by Julian Auber of the University of Paris thinks they may have cracked the
27:23code.
27:24Thanks to collaboration between historians and mathematicians, we now have maps of geomagnetic
27:29variations dating back to 1590.
27:32It's with these maps that Auber created a model.
27:35This model suggests that gravity aligns the inner core and the mantle, which in turn forces
27:40liquid metal into the outer core.
27:42This liquid metal moves in enormous rotating vortexes.
27:47When expelled, this metal is pushed westward, and since these gyres are concentrated at
27:51low latitudes, the magnetic field at low latitudes sees the most activity.
27:56However, this doesn't explain everything.
27:58As noted by O.P.
27:59Bardsley of the University of Cambridge, while it may be the case that gyres just happen
28:03to be moving westward, there's still no particular reason why gyres should exist, and no definite
28:08proof that they do.
28:10No matter how this underground movement is happening, Bardsley suggests that Rossby waves
28:15are likely playing a role.
28:17In essence, these are slow waves that arise in rotating fluids.
28:21Also known as planetary waves, they're found in many large, rotating bodies, including
28:26on Earth, in the oceans, and the atmosphere on Jupiter and the sun.
28:30Since the Earth's outer core is also a rotating fluid, possibly waves circulate there too.
28:36What Bardsley has observed is that while the crest of these Rossby waves tend to move east,
28:41there is a possibility that the bulk of the energy has a tendency to move westward.
28:45Those waves could in turn help explain why gyres act the way that they do.
28:49The problem with this gyre movement is that they may be creating change in our magnetic
28:54pole.
28:55More specifically, there are some scientists who believe that the north and south poles
28:59may currently be in the process of switching sides.
29:02Now, this has happened before.
29:04According to our data, the last magnetic pole reversal happened 780,000 years ago.
29:09However, the reality is that experts are split on the issue, as this movement may very well
29:14just be an anomaly.
29:16However, if the Earth's poles were to reverse, the results would be catastrophic.
29:21Animal species such as turtles, salmon, and whales that use the Earth's magnetic field
29:25for navigation during migration would likely have completely messed up travel paths, and
29:30many wouldn't survive the change.
29:32If that wasn't bad enough, the magnetic field would also become weaker during the switch,
29:37causing the planet to be bombarded with lethal particles from the sun and warming up the
29:41Earth's surface temperature.
29:43To top all this off, the charged particles would seriously disrupt our tech.
29:48Solar wind or cosmic rays colliding with electronic circuits and satellites could render them
29:52useless.
29:53So, while having a pole switch is hopefully not on the horizon, if there were to be one,
29:59it would wreak absolute havoc on us.
30:02Try to have a better day after listening to all of that.
30:05I'll see you next time.