New Information About the Blobs in the Center of Earth

Now scientists think they know what made them.

Hiya!

It’s incredible, isn’t it? How our idea of what we do or don’t know about our planet and so many other things sort of solidifies once we leave school. Yet, experts continue exploring and learning new things long after we graduate. I suppose that’s one of the reasons this newsletter exists: to learn about all the cool things scientists are discovering.

For instance, I doubt you learned about the giant mysterious blobs near the Earth’s center in school. Yet, scientists found exactly that, though there’s plenty of debate about what they’re made of and why they exist at all. Then again, a recent study added some weight to one theory in particular.

The Blobs

I’ve written about the Blobs before, which you can read for additional information if you’re curious, though I’ll discuss them briefly here.

You likely know there are many layers to the Earth. There is the super-hot and dense inner core that is metallic and surrounded by a thicker rotating molten layer, which creates a 1,500-mile-wide outer core. Insulating the combined core is the mantle, responsible for 80 percent of Earth’s volume, and on top of that, a comparatively much thinner Crust, aka the surface.

The mantle is where most of Earth’s internal activity occurs, where plates collide and rub against each other, and magma squishes in their cracks and caverns. Despite all its excitement, the mantle’s depth and size make it challenging for researchers to study directly.

So, instead, in the 1970s, scientists analyzed the planet’s seismic activity and mapped how seismic waves move during earthquakes. Thanks to physics, this approach also tells experts the densities of the materials the waves pass through — the thickness of the material can influence the wave’s speed and direction. This is called seismic tomography, and using this information, researchers created a map of Earth’s interior.

In the process, seismologists identified two gigantic blobs near the center of Earth — one under the Pacific Ocean and the other beneath Africa and the Atlantic Ocean — that are made of denser materials than the surrounding mantle. This suggests they’re made of different stuff. Scientists have named them large low-shear-velocity provinces (LLSVPs), but I prefer calling them the Blobs.

In case you’re underestimating just how large these blobs are, allow me to put them in perspective. They are each longer than a continent, and if they were on Earth’s surface, the International Space Station would have to navigate around them. Combined, the blobs make up between 3 and 9 percent of Earth’s volume.

There have been plenty of studies investigating the blobs, which seem to have been around for billions of years, though scientists still aren’t sure exactly how the giant blobs formed or what they’re made of.

There are, of course, many theories and a recent study by an international team of scientists added more weight to one in particular — involving an ancient planet and our Moon.