00:00Earth isn't a perfect ball, we know that. But the real mystery is miles beneath our feet.
00:06Way down below the crust, the planet has been cooling down for billions of years,
00:11just not evenly. The Pacific side loses heat faster, while the African side slows that loss
00:17by trapping it longer. That difference is why Earth stays restless, with earthquakes tearing
00:23the ground apart, and volcanic fire breaking through the surface. Think of Earth like a massive
00:30engine that's been shut off. The outside cools first, but deep inside, heat lingers. That internal
00:36heat is leftover energy from when the planet formed, and it's been slowly trying to escape ever since.
00:42For a long time, scientists assumed Earth lost heat evenly in all directions. Hot in the middle,
00:48slowly cooling everywhere else. But when a team at the University of Oslo ran simulations that
00:54rewound the planet 400 million years and tracked where the heat actually escaped, they saw something
01:00very different. The cooling wasn't symmetrical at all. One side of the planet is doing it faster than
01:07the other. The difference is striking. The Pacific Hemisphere, the side dominated by the world's
01:12largest and deepest ocean, has cooled by about 50 degrees Kelvin, which is roughly 90 degrees
01:18Fahrenheit difference, compared to the Africa-Eurasia side. The reason is basically insulation.
01:26Africa and Eurasia are on a layered ancient continental crust. The Pacific side is the opposite.
01:32It's mostly ocean, resting on a much thinner crust where warmth escapes easily. Plus, the cold seawater on
01:39top pulls that heat out non-stop. Because the Pacific side is cooling so fast, the rock deep underground
01:47is getting heavy and sinking back toward the core. It's like a giant slow-motion conveyor belt that drags
01:53the Earth's crust down with it. Heavy materials sink. As it sinks, it pulls on the edges of tectonic plates,
02:01creating stress, trenches, earthquakes, and chains of volcanoes.
02:05Most of Earth's earthquakes and volcanoes happen in a giant loop called the Ring of Fire. This is where
02:13the ocean floor gets cold, heavy, and sinks deep into the planet. All that sinking rock travels thousands
02:20of miles down until it slams into a massive continent-sized structure sitting right near Earth's core.
02:27Scientists call this a blob because the heavy ocean floor is constantly falling on top of it. The Pacific
02:34blob is squashed flat and pinned down, sitting heavy and locked in place. But the other half of the
02:40world is doing the exact opposite. Under Africa, there aren't many sinking plates to act as a weight.
02:47Without that pressure holding it down, the African blob is free to grow tall and light. It pushes upward,
02:54lifting the ground from below and reshaping the entire continent. In fact, that rising bubble is already
03:00starting to tear the surface apart. In East Africa, a massive crack known as the Great Rift Valley is
03:07slowly opening up as the ground is pushed from below. Eventually, the pressure will become so high
03:14that Africa will literally split in two, allowing a brand new ocean to rush into the gap.
03:21There's a cool theory that suggests these blobs might actually be the remains of an ancient planet
03:27named Theia. Some researchers believe that Theia crashed into Earth billions of years ago,
03:32and while part of it broke off to form the Moon, some heavy chunks might have sunk deep inside our
03:38planet. So, the reason our interior is so lopsided might be because we literally have pieces of a
03:45different world buried inside our own. But that's just a wild theory. Whatever their origin, the blobs
03:52matter because they help split the planet into two different behaviors. On the Pacific side,
03:57cold slabs keep sinking down and piling up. On the opposite side, heat builds up deep and pushes
04:03upward over time. One half is dominated by downward motion, the other by upward motion. And this imbalance
04:11doesn't stop at the mantle. It shows up at the very center of the planet because Earth's inner core is
04:17still growing. Liquid iron around it gradually turns solid and attaches to the core. This process doesn't
04:24progress at the same rate everywhere. One side of the inner core builds up faster than the other.
04:31This might sound like it should throw the planet off balance, but it doesn't. Earth's interior isn't
04:37rigid like a solid metal ball. Over time, stuff inside can gradually move around. Gravity pulls everything
04:44toward the center, helping everything get a bit smoother and keeping the core pretty round. But
04:50pretty round doesn't mean perfect. If you want a real example of how uneven Earth is on the inside,
04:56look at the Indian Ocean. Where there's more mass underground, gravity pulls a little harder. Where
05:03there's less mass, it pulls less. In the middle of the Indian Ocean, there's a huge anomaly called the
05:09Indian Ocean Gravity Hole. In that spot, Earth's pull is weaker than normal, so weak that it can't
05:16hold the ocean surface up at the usual level. The water actually dips downward. You wouldn't notice it
05:23sailing through, but you'd technically be sitting about 300 feet lower than the rest of the world's
05:28oceans. It's an invisible valley in the sea caused entirely by missing mass deep inside the planet.
05:36However, Earth isn't the only world hiding a messy interior behind a smooth surface. Even the Moon
05:43is like this. Over billions of years, Earth's gravity slowed the Moon's rotation until it locked into
05:49place, keeping one face permanently pointed toward Earth. That's what we know as the near side and the
05:56far side. This mattered early in the Moon's history. The near side always faced Earth, while the far side
06:02always faced deep space. That long-term setup affected how heat was stored and released inside the Moon.
06:10When NASA mapped the Moon's gravity using two spacecraft called GRAIL, they measured something
06:16called the love number. It's a value that tells scientists how much a planet or Moon flexes under
06:22gravity. The Moon's love number turned out higher than expected, which meant its interior was softer than
06:28it should be. When scientists looked closer at the gravity data, they found that most of this
06:33flexibility came from the side facing Earth. The Moon's near side is softer and warmer deep down,
06:41while the far side is cooler and more rigid. Measurements suggest the near side mantle is
06:46significantly hotter and more volcanic. That difference shows on the outside. Because the near side was so hot
06:54and soft, ancient lava could easily punch through the crust and flood the surface. That created those
06:59big dark patches we see at night. On the other hand, the far side stayed colder and stiffer, so the
07:06lava never flowed the same way. Back on Earth, the Pacific has another quirk worth mentioning. Our planet
07:14isn't just spinning in place. It orbits the Sun at over 66,000 miles per hour, and the entire solar system
07:20is moving through the galaxy like a car driving through a swarm of bugs. Over long periods of time,
07:27objects drifting in from deep space are more likely to hit the side of Earth that's moving forward.
07:32And because the Pacific Ocean covers such a huge stretch of that side of the planet,
07:37it naturally ends up catching more impacts than smaller oceans or continents. This creates a strange
07:44coincidence. The same hemisphere that is leaking the most heat from within is also the world's biggest
07:50graveyard for things arriving from the outside. Because it is so vast and lonely, space agencies
07:56even use its most remote coordinates as a spacecraft cemetery at a spot called Point Nemo. We deliberately
08:04aim satellites and massive space stations like Mir to crash right there. So the Pacific ends up taking
08:11the hits from two directions, by accident from the universe and on purpose from us. Earth is restless,
08:18continents drift, oceans open and close. In a few hundred million years, the map will look
08:24completely different. The Pacific is actually shrinking right now. Eventually, the Americas might crash into
08:31Asia, and a new ocean will have to take over the job of being the planet's main radiator and its front bumper.
08:37But for now, we should probably be thankful for that massive, chilly, unlucky ocean.
08:45That's it for today. So hey, if you pacified your curiosity, then give the video a like and share
08:50it with your friends. Or if you want more, just click on these videos and stay on the Bright Side!
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