Once upon a time, billions of years ago, Earth experienced a massive space crash with another planet, which led to the creation of our Moon. But that’s not the whole story.
Deep inside our planet, scientists have found something extraordinary—two huge blobs of mysterious material, each one twice as big as our Moon!
These blobs aren’t like the rest of the stuff inside the Earth; they’re different.
They’ve been hiding near the center of the Earth, one beneath Africa and another beneath the Pacific Ocean.
Researchers have been scratching their heads about these blobs for decades, but now, a team from Caltech has come up with an exciting theory: these giant blobs might actually be pieces of the planet that hit Earth long ago!
For a long time, the big question was where the Moon came from. Scientists think it was born when Earth had a huge crash with a smaller planet called Theia.
The problem was, nobody could find any bits of Theia floating around in space or stuck in meteorites.
Now, the Caltech scientists say most of Theia didn’t get blasted into space; it got swallowed up by Earth and turned into those two big blobs, while the rest of the debris stuck together to make the Moon.
The discovery of these blobs happened because of something called seismic waves. These are like sound waves that travel through the Earth when there are earthquakes.
By looking at how these waves move through Earth, scientists in the 1980s noticed that some parts of the deep Earth made the waves slow down.
This slowness hinted that something unusual was down there—what we now know as the big blobs, officially called large low-velocity provinces (LLVPs).
So how did the Caltech team figure out the blobs might be from Theia? It all started with a seminar on how planets are made, where Professor Mikhail Zolotov mentioned that nobody knew where Theia ended up.
That’s when Qian Yuan, a geophysicist, had his lightbulb moment. He realized that if Theia was full of iron and the Moon had lots of iron, then maybe Theia was hiding in plain sight—inside Earth!
With a group of smart collaborators from different fields, Qian Yuan used computers to simulate the crash between Earth and Theia. The simulations showed them that the crash could have made both the Moon and the blobs inside Earth.
It seems that parts of Theia’s guts mixed with Earth’s own insides, and over time, they clumped together to form the big blobs we see today. The rest of the debris ended up sticking together to form the Moon.
The reason Theia’s pieces stayed in big blobs instead of mixing all through Earth’s insides is that the crash didn’t heat up the whole Earth.
Most of the heat stayed up top, so the lower parts stayed cooler, and Theia’s iron-rich pieces could just drift down and settle like blobs of wax sinking in a lava lamp that’s turned off. If it had been hotter, everything would have mixed up like paint colors swirling together.
Now, the scientists want to explore how having Theia’s leftovers deep inside Earth might have changed the way our planet grew and changed, like how the continents formed and how the very first bits of Earth’s crust moved around.
The big takeaway? Parts of another world are buried deep within our own, and these ancient pieces might have shaped everything we see around us today.
It’s a cosmic mystery that’s slowly getting unraveled, and who knows what other secrets are waiting deep in the heart of our planet!
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