15 INSANE Facts about Earth.

Discover the Wonders of Our Planet, we're counting down the 15 most astonishing facts about the Earth. 15. The Earth May Have Had Two Moons According to some reports, Earth may have had two moons in the distant past. The theory goes that a tiny second moon once orbited Earth before catastrophically slamming into the other one. This would explain why the dark side of the moon looks so different than the side we see every night, as the dark side may have been pancaked by this smaller moon before it either 14. Days Are Getting Longer When the Earth was formed about 4.6 billion years ago, a day would have been roughly six hours long. Now the number is 24, and every century that number increases by about 1.7 milliseconds. This could be a result of climate change, according to Professor Duncan Agnew from the Scripps Institution of Oceanography. As polar ice melts, the water spreads out over the whole ocean, causing the same effect as the skaters spreading their arms out. The Earth slows down. 13. The Earth Used To Be Purple While this one's still up for debate, there are some scientists who believe that the Earth was once purple. The basic idea behind this claim is that while today's plants are green thanks to chlorophyll, in the past, ancient plants may have had a different molecule to harness the sun's rays. Known as retinol, it would have given organisms a violet hue. However, because chlorophyll was more efficient, it likely beat out retinol, giving the world the green color it's got today. Yeah, I think I prefer green. 12. The Earth's Largest Structure Pause this video for a moment and guess, what's the largest structure on the planet? Most likely, you guessed the Burj Khalifa in Dubai, which is the world's tallest building. Or the Tesla Gigafactory, which is the world's largest building by surface area. Unfortunately, you're not even close. That's because the world record belongs to Australia's Great Barrier Reef. This massive coral structure is a whopping 348,000 square kilometers, making it many times larger than any human-built structure on the planet. 11. The Third Pole Believe it or not, the Earth has three poles. Well, kind of. While the North and the South Pole are the Earth's first two poles, in some ways the Tibetan Plateau acts as a third. It's located at the intersection of South Central and East Asia. It's a land of large glaciers, permafrost, and heavy snow that feeds the Ganges, Indus, Mekong, Yangtze, and Yellow Rivers. This vast amount of water, ice, and mountain range affects the atmospheric circulation and drives weather patterns across the continent. The effect is so strong that it has many of the capabilities of our North and South Poles. 10. The Earth Isn't Round Before the conspiracy nuts get too excited, I'm not saying that the Earth is flat. However, it's far from a perfect sphere. While it may look this way from a distance, the reality is that the Earth's shape is constantly changing. The best word we have to describe this shape is an ellipsoid, that is to say a deformed, not perfectly symmetrical sphere. However, even this strange shape doesn't perfectly explain the Earth's strange form. You see, our planet's diameter bulges at the equator and it flattens a bit at the poles due to the centrifugal forces created by the Earth's constant rotation. As explained by geologist Vic Baker of the University of Arizona, "...instead of Earth being like a spinning top made of steel, it has a bit of plasticity that allows the shape to deform very slightly. The effect would be similar to spinning a bit of silly putty, though Earth's plasticity is much, much less than that of the silicone plastic clay so familiar to children." Additionally, mountains rising to heights of about 9,100 meters and ocean trenches diving down to nearly 11,000 meters below sea level further distort the Earth's shape. Even at sea level, things aren't perfect. After all, sea level is irregularly shaped, as slight variations in the Earth's gravity cause permanent hills and valleys in the ocean's surface that often measure in at over 90 meters in height. In addition to these stable oddities, the Earth also has changes that are periodic or random in nature. For example, tides affect both the ocean and the crust on a daily basis, while the drift of tectonic plates and rebound of the crust after a heavy sheet of ice has melted is slow and gradual. From time to time, earthquakes, volcanic eruptions, and meteor strikes also hit our planet, changing its shape in ways that are unpredictable. Interestingly, America's National Geodetic Survey has made it its mission to measure and monitor the ever-changing size and shape of the Earth. This in turn not only provides us with a constant idea of the Earth's form, but it also allows us to plan our structures, shipping routes, and building strategies accordingly. 9. The Earth Has An End Date Much like a carton of milk or a bag of avocados, the Earth has a best-before date. That is to say, there will come a time when the Earth will be uninhabitable, and in some ways, that date is in our control. The rather obvious within-our-control date would be brought upon by climate change. that the Earth is warming faster than it should be through natural means. Without going through points that you've probably heard before, the bottom line is that this will increase natural disasters, flood coastal cities, and make it near-impossible to farm in most areas of the world, among many other things. In time, this would make at least many parts of the Earth unlivable, with the effects being especially bad in poorer areas. While those in rich countries at high altitudes will probably be better off, if left unchecked, climate change will lead to end-of-life, global economies, and luxuries we enjoy. However, the reality is that while climate change will dramatically change human life, it likely won't lead to the planet's end. This doesn't mean that we're completely in the clear, though. That's because it's believed that the Earth will become unlivable for most organisms in about 1.3 billion years, due to the Sun's natural evolution. That's because at this point, sustained hot and humid conditions will make the planet unlivable, and in about 2 billion years, the oceans will likely evaporate, and in time, our atmosphere will eventually disappear. While extremophiles, that is to say, small organisms that live in volcanic vents deep under the sea, might be able to eke it out, we humans won't stand a chance. However, even those extremophiles will eventually meet their demise. That's because in about 4.5 billion years, the Sun will become a large red giant that will engulf the Earth, completely destroying everything that's still left. And if that wasn't bad enough, there's still a chance that other occurrences such as nuclear wars or even asteroids hitting our planet could also end human life. So therefore, the harsh reality is that while Earth may have an end date that's billions of years away, we're probably going to be off this planet far sooner than that. 8. The Earth's core is as hot as the surface of the Sun When you think of the Sun, you probably think about a hot ball that would immediately burn up anything that got too close. However, despite being so insanely hot, it turns out that our planet's core packs just as much heat. That's because it turns out that both the Earth's core and the surface of the Sun are both a little over 6,000 degrees Celsius. This leaves us with an important question, how can Earth's core be so hot without simply burning up the planet? Well, the best way to think of the Earth is like an onion. Every time you go down a certain amount of meters, you reach another layer. Starting from the top down, there's the crust, which includes the surface that we walk on. Then farther down, the mantle, which is mostly solid rock. Then even deeper, the outer core, made of liquid iron. And finally, the inner core, made of solid iron, probably. And with a radius that's about 70% the size of the Moon's. The deeper you dive, the hotter it gets, until you reach the hottest spots at the center. Yet because of the existence of these layers, this inner heat is not able to penetrate all the way up to the planet's surface, saving us from our destruction. The Earth seemed to have picked up all this heat about 4.5 billion years ago. The first bit was inherited during our planet's formation. You see, the Earth was made from the solar nebula. This was a giant gassy cloud, and when the planets were forming, there were endless collisions and mergers between different rocks. This movement created enormous amounts of heat, and some of that heat was locked inside the Earth. The other heat source was the decay of radioactive isotopes. Distributed across the Earth, these tend to release energy underground, and along with the hot core and mantle, they provide the heat necessary to drive the motion of the Earth's plates. Now, here's the crazy part. If the Earth's core had no heat, there would be no plate movement, and therefore, no life. That's because without plates continuously moving, the Earth would have had a weaker atmosphere and would have been far colder than it is today. This would have, in turn, made human life impossible. So therefore, we owe a lot to our planet's super hot core. Moving on to number 7. The Moon Is Drifting Away From Us 300 years ago, the famous English astronomer Edmund Halley hypothesized that the moon was moving away from us after studying records of ancient eclipses. In the 1970s, that hypothesis was confirmed. You see, during the Apollo missions, NASA put mirrors on the moon. Scientists then bounced laser beams off them and used the measurements to determine that the moon was indeed moving away from the Earth at a rate of 3.8 centimeters per year. For reference, that's roughly the rate at which fingernails grow, making this change a small yet calculable one. This can be explained by the effect of the moon's gravity on the rotating Earth. The moon is responsible for the Earth's tides, and as these are raised, they cause drag that slows the Earth's spin rate down. This resulting loss of angular momentum is compensated by the moon speeding up, and this in turn causes it to move further away. As put by astrophysicist Madeline Broome of the University of California, quote, Since the Earth and the moon are a part of the same gravitationally interacting system, total angular momentum must be conserved between the two. As the Earth's spin slows down thanks to tidal drag, in order for angular momentum to be conserved, something has to increase the angular momentum of this system, end quote. Well, the moon moving further away increases that angular momentum. However, there is a small mathematical problem with this model. At the current rate of the recession, the calculations show that the moon must have separated from the Earth about 1.5 billion years ago, which is far more recently than the geological evidence suggests. While this may seem fatal to the entire theory, astronomers have an explanation. They argue that the recession rate must have been slower in the past. This is because phenomena like continental drift, which altered the size and depth of the oceans, must have in turn altered the amount of tidal drag. When you take this into account, this pushes the date of the separation back by several billion years, thereby putting the standard hypothesis in line with the geological evidence. Well, of course, this all leaves us with an interesting question. Will the Earth ever lose its moon? The short answer is no. In fact, calculations of the evolving Earth-moon system tell us that in about 15 billion years, the moon will actually stop moving away from the Earth. However, since the Earth will likely be engulfed by the sun in the next 4 billion, we're never going to get to see that in action. 6. The Ocean is Filled with Gold While the world's oceans may look like a long expanse of water, the reality is that they're filled with minerals, with the most desirable among them being gold. Estimates as to how much gold exists in our ocean varies, however, there's believed to be about 1 gram of gold for every 100 million tons of ocean water in the Atlantic and North Pacific. However, since all this gold is located in tiny concentrations within the water, extracting it would be difficult. Yet that doesn't mean that it wouldn't be impossible, and to date, the most effective method would likely be gold dredging. This process involves using a vessel with a giant scooper to remove sediment from the ocean floor. The sediment is then processed to extract the gold. But this process is not only expensive, it's also harmful to the environment, as the dredging process can damage marine habitats and release toxins into the water. There are also other methods of extracting gold from the ocean, such as using magnetic nanoparticles or bacteria. However, these methods are still experimental, and their feasibility is yet to be established. That doesn't mean that gold couldn't be extracted from the Earth's oceans in another way. That's because much like the oil reserves reached by oil rigs, there are also gold reserves buried underwater. The only problem is, these deposits are often multiple kilometers below the ocean's surface and encased in rock. This makes mining pretty difficult, and with current technology and at current prices, it's impossible to extract the gold down there while still turning a profit. Yet given the fact that there may be as much as 20 million tons of gold in total spread across the Earth's oceans, it's likely that at some point, some sort of ocean gold extraction may be attempted. Oh, by the way, the ocean isn't the only place on Earth with unreachable gold. According to scientists, the Earth's core is believed to contain vast amounts of gold, by some estimates, as much as 1.5 quadrillion tons. However, because it's located about 2,900 kilometers below the surface of the Earth, reaching it today would be impossible. So while the Earth may have a lot of hidden gold, the sad reality is that you won't be getting your hands on it anytime soon. 5. The Moon is the Earth's Child While there are multiple theories about how the Moon was formed, the most widely accepted is the Giant Impact Theory. The basic idea behind it is that the Moon formed during a collision between the Earth and another smaller planet about the size of Mars. The debris from this impact collected in orbit around the Earth to form the Moon, while the impact on Earth was gradually smoothed away, allowing the Earth to maintain its roughly spherical shape. This theory is supported by the evidence brought back from NASA's Apollo program. In total, these missions brought back over a third of a ton of rock and soil from the Moon. When analyzed, researchers found that the Earth and Moon have some remarkable chemical and isotopic similarities. Now, if the Moon had been created elsewhere and was simply captured by Earth's gravity, its composition would have been very different from that of Earth. Instead, the fact that the composition of the Earth and Moon are very similar suggests there is a linked history. However, this doesn't mean that the debate is fully settled. After all, while the composition is similar, it isn't the same. That's because the minerals on the Moon contain less water than those of similar rocks on Earth. This has forced scientists to take a long, hard look at the giant impact model, and to date, the explanation for this difference may lie in the details. The most common idea now is that when the Earth and the Mars-sized planet collided, they were two similar yet not identical planets. While most of the material from the collision melted and fused to form the modern Earth, a small part of the new mass became the Moon as we know it. Since this breakaway piece may have contained more of one planet than another, this may explain the slight differences between the two planets. To date, scientists have tried to create models that adjust the sizes of the two planets and the impact angles to get the nearest possible match. That work is still ongoing, however, it is worth mentioning that there are a few other explanations for how the Moon formed. Perhaps the second most common is the capture theory. This hypothesis suggests that the Moon was a wandering body that formed elsewhere in the solar system and was captured by the Earth's gravity. Others, instead, subscribe to the accretion theory. This idea proposed that the Moon was created alongside the Earth at the time of the Earth's formation. There are some who even subscribe to the fission theory, which posits that at some point the Earth had been spinning so fast that some material broke away and began to orbit the planet. However, extensive debates on the subject in the 1970s and 80s have all but put those theories to rest, and today, the giant impact theory reigns supreme. 4. Gravity Isn't Uniform Ever since the apple fell on Isaac Newton's head, the theory of gravity has been progressively developed. However, the way the force of gravity works isn't the same everywhere on Earth. That's because depending on where you're standing, the amount of gravity weighing on you will be quite different. In order to calculate these differences, we have to look at a few factors. The first is the latitudinal effect. You see, the Earth isn't perfectly round. Rather, it gets flatter the closer you get to the poles, and it bulges out the closer you get to the equator. As a result, the distance from the Earth's center to sea level is about 21 km greater at the equator than it is at the poles. Now, translated into gravitational terms, you weigh 0.5% more at the poles than you do at the equator. The second factor is the rotational effect. You see, the Earth spins faster at the equator than it does at the poles, and this influences the strength of the force of gravity. Altitude also has an effect. You see, Earth's gravitational pull depends on your distance from its center. So therefore, gravity diminishes with altitude. For example, if you were 5 km up a mountain, you would weigh 99.84% of what the scales would say at sea level. The fourth factor is the force of the tide. Now essentially, tides are caused by the pull of the Moon's gravity on the Earth. Now this change can in turn affect the amount of gravity you experience. Finally, the density of certain rock types also has an effect on the force of gravity. Areas with higher subsurface rock density have higher than average gravity. As such, while mountains increase gravitational density, ocean trenches decrease it. However, this effect is pretty small. Usually, it isn't greater than 0.01%. Now while the first four factors can be compensated for mathematically, it's the local geology which produces random gravity anomalies. In order to visualize the impact of these anomalies, most scientists use a gravity anomaly map named in honor of the 18th century French scientist Pierre Bouguet. It was he who discovered that a small regional variation in the Earth's gravity field could be related to the varying density of underground rocks. The Bouguet gravity maps makes it possible to see how these variations are distributed, with areas of lower gravitational pull being colored more red and areas with higher gravitational being colored more blue. Using such a map, we can see that a country like the US, even state to state differences are calculable. For example, if Newton's apple were to have fallen on him in southern Illinois, it would have weighed a bit more than it would have had in central Indiana. Of course, these effects are rather minute. In reality, they only account for variations in decimal points. Yet, despite the effects being small, they can have a noticeable impact. For example, it can cause the sea to bulge in certain places and throw pendulum clocks out of sync. In areas of science where exact precision is of the essence, it's therefore essential that these variations in gravity are precisely understood. 3. The Earth May Have A Population Limit While the idea of the Earth having a population limit may seem obvious, exactly what that would look like is something that's one of the Earth's greatest existential mysteries. The first real look into this dilemma was recorded by Dutch scientist Antonie van Leeuwenhoek in 1679. He reasoned that his home country of Holland occupied one part in 13,000 of Earth's habitable land, and so multiplied Holland's population of 1 million people by 13,000 to get a total capacity of 13 billion people. Since then, our understanding of how population limits work has advanced quite a bit. Nowadays, this common concept is the Thomas Malthus idea of carrying capacity. That is, the maximum number of people who could live on Earth after considering both natural constraints and human choices. In context, natural constraints include food scarcity and inhospitable environments, while human choices include interactions between economics and culture, such as how we produce and consume goods, as well as birth rates, average lifespans, and migrations. Another central component to carrying capacity is that it's indefinite, that is to say it calculates the maximum population that is sustainable indefinitely. This means that while it is possible for Earth to function beyond its carrying capacity, this would eventually end in disaster long-term. Now, what's really interesting about this number is that it's not static. After all, humans in different geographies produce and consume at different rates, and how all of this is distributed dramatically affects carrying capacity. In terms of trying to pinpoint a number, the United Nations Population Division projects that the world population will reach 10.4 billion people sometime in the 2080s and remain there until 2100. However, whether or not that reflects a true maximum is impossible to know right now. Unsurprisingly, there's a lot of studies that have tried to answer this question, but going through all of them would be a better fit for a documentary than a YouTube video. When the United Nations Environment Program looked at all the major ones, they found that the vast majority of the studies showed that a number is somewhere between 4 and 16 billion people. Given the fact that our planet has about 8.1 billion people already, this rather low number is a cause for concern. However, given that the studies range from anywhere between 2 billion and 1.2 trillion, it's hard to get a definitive conclusion. Now, while we may not actually have a fixed carrying capacity, what we do have are methods to ensure that we never get there anyway. For example, one study published in the prestigious academic journal Proceedings of the National Academy of Sciences found that if the population of the United States switched to a vegetarian diet, the land used to grow crops for humans rather than animal feed for meat production would feed an additional 350 million Americans. Furthermore, the numbers indicate that places where women have increased access to education and family planning, they tend to have lower birth rates and smaller family sizes than in middle and lower income countries where they may not. So, while we may never know the Earth's true carrying capacity, it's most certainly in the interest of the humanities to not test the upper boundaries if possible. 2. We're Often Hit By Space Rocks When you think of an asteroid hitting Earth, you likely think of a massive hunk of rock that wiped out the dinosaurs 66 million years ago. However, it turns out that asteroids come in all shapes and sizes, and when looked at in totality, we deal with these pesky space rocks almost every single day. First and foremost, it's worth clearing up the difference between asteroids, meteors, and comets, as these terms are often used interchangeably but don't mean the same thing. A comet is an object consisting of ice and dust that orbits the sun. These typically do not hit Earth. A meteor is a small piece of an asteroid that burns up after entering the Earth's atmosphere. These tiny guys are pretty common, as about 17,000 of them fall to Earth each year. However, because they burn up so quickly, they usually reach the Earth's surface as dust and don't have much of an impact. Now asteroids are something entirely different. Unlike meteors and meteorites, which are small, asteroids are larger space rocks that don't fully burn when going through the atmosphere. When they hit the Earth, they have the ability to cause a lot of damage. However, exactly how much damage is relative to their size. The smallest asteroids that are cause for concern are between 25 and 140 meters in diameter. These are relatively rare. On the larger end, those that are more than 100 meters in diameter only hit the Earth once every 10,000 years or so. However, when they do touch down, they can cause a lot of local damage. One recent example happened in 2013 over the Russian Oblast of Chelyabinsk. After exploding at a height of about 39 kilometers, the 18-meter-wide meteor created a massive shockwave. In total, it damaged about 7,000 buildings across six cities and injured about 1,500 people. However, the most destructive was the so-called Tunguska event happening in Siberia in 1908. It may have been as much as 100 meters in size. However, despite being so large, the rock was never recovered and it's believed that it likely burned up at an altitude between 5 and 10 kilometers. While these types of asteroids are manageable, those that are between 140 meters and a kilometer in diameter are way more destructive. These are able to devastate entire regions, causing horrific events such as fires, tsunamis, and massive changes. Thankfully, these are pretty rare. They only happen every 10,000 years or so, and none are believed to have occurred within recorded history. Yet the most terrifying asteroids of them all are those over a kilometer in diameter. These types of collisions are globally catastrophic. They have the potential to cause mass extinction. The most famous example of one was the asteroid that wiped out the dinosaurs, coming in at between 10 to 15 kilometers in diameter. It radically changed the Earth's climate. As far as we know, very few species survived the disaster. However, some of those that did include several types of birds, lizards, turtles, and crocodilians. Yet what has survived are remnants of the asteroid. Located in the Yucatan Peninsula, most of the crater has been covered by hundreds of meters of limestone or filled in by the waters of the Gulf of Mexico. However, there are still some areas on Mexico's mainland that are visibly deeper, thanks to this impact. Well, thankfully, we're not due for a similar event during our lifetimes, according to NASA's Jet Propulsion Laboratory. There's no currently known significant threat of impact for the next hundred years or more. So I guess you can rest easy at night knowing that no world-ending asteroids will be interrupting your sleep. 1. The Earth's Magnetic Field is Creeping Westward The Earth's magnetic field is massively important. After all, it's the shield that protects us from the charged particles streaming from the sun, and it keeps us from becoming a barren, Mars-like rock. However, for the past 300 years or so, this magnetic field has slowly drifted westward at a rate of about 17 kilometers per year. Scientists have known this for quite a while. The astronomer Edmund Halley is the first to observe it all the way back in 1692. However, despite centuries of work on the subject, we don't know exactly why this westward shift is happening. For some context, the Earth's magnetic field is created by interactions deep inside the Earth's core. While the inner core is presumably solid, the outer core features flowing liquid iron, which generates current that in turn leads to magnetic fields. This field changes over time, with certain areas receiving better coverage than others. However, what's weird is that in the low latitudes of the Western Hemisphere, these changes are especially obvious. While these changes are certainly driven by the intense activity in the core, for years scientists were not sure why these areas were affected more severely. But, a team led by Julian Auber of the University of Paris thinks they may have cracked the code. Thanks to collaboration between historians and mathematicians, we now have maps of geomagnetic variations dating back to 1590. It's with these maps that Auber created a model. This model suggests that gravity aligns the inner core and the mantle, which in turn forces liquid metal into the outer core. This liquid metal moves in enormous rotating vortexes. When expelled, this metal is pushed westward, and since these gyres are concentrated at low latitudes, the magnetic field at low latitudes sees the most activity. However, this doesn't explain everything. As noted by O.P. Bardsley of the University of Cambridge, while it may be the case that gyres just happen to be moving westward, there's still no particular reason why gyres should exist, and no definite proof that they do. No matter how this underground movement is happening, Bardsley suggests that Rossby waves are likely playing a role. In essence, these are slow waves that arise in rotating fluids. Also known as planetary waves, they are found in many large, rotating bodies, including on Earth, in the oceans, and the atmosphere on Jupiter and the sun. Since the Earth's outer core is also a rotating fluid, possibly waves circulate there too. What Bardsley has observed is that while the crest of these Rossby waves tend to move east, there is a possibility that the bulk of the energy has a tendency to move westward. Those waves could in turn help explain why gyres act the way that they do. The problem with this gyre movement is that they may be creating change in our magnetic pole. More specifically, there are some scientists who believe that the north and south poles may currently be in the process of switching sides. Now, this has happened before. According to our data, the last magnetic pole reversal happened 780,000 years ago. However, the reality is that experts are split on the issue, as this movement may very well just be an anomaly. However, if the Earth's poles were to reverse, the results would be catastrophic. Animal species such as turtles, salmon, and whales that use the Earth's magnetic field for navigation during migration would likely have completely messed up travel paths, and many wouldn't survive the change. If that wasn't bad enough, the magnetic field would also become weaker during the switch, causing the planet to be bombarded with lethal particles from the sun and warming up the Earth's surface temperature. To top all this off, the charged particles would seriously disrupt our tech. Solar wind or cosmic rays colliding with electronic circuits and satellites could render them useless. So, while having a pole switch is hopefully not on the horizon, if there were to be one, it would wreak absolute havoc on us. Try to have a better day after listening to all of that. I'll see you next time. Thank you to our channel members.