Decades have passed since scientists first understood that there were two ginormous lumps buried deep under the Earth's surface. Theories have come and gone, but now, new findings point to remnants of a cosmic crash as the root cause of this mysterious phenomenon.
For those who need a little refresher, planet Earth's composition has been likened to a multi-faceted cake. While the outer layer, the one that we live on, has all the makings of a steady and firm baked good, the inner layers can be far more tumultuous. Some are hard and rocky, others are more fluid-like. And deep in the "cake's" insides lie two continent-sized lumps. They make up roughly a third of the buffer between the Earth's mantle and core and are significantly hotter than any surrounding materials. But even with these details, so many questions remain. Mainly what are they made of and how did they get there? Dating these giant lumps have been a major priority for geologists all around the world because their age can answer important questions about our planet and how it was formed.
As Sujoy Mukhopadhyay from the University of California put it, "if these things are truly ancient, it tells us something about how our planet formed." New findings show that these blobs (scientifically referred to as Large Low-Shear-Velocity Provinces) are the leftovers of a catastrophic collision between Earth and Theia (a protoplanet) from roughly 4.5 million years ago. But the LLSVPs aren't the only thing to come out of the crash - the Moon as well was formed by this event! According to Qian Yuan of Arizona State University, the scientific community is quite certain that these two giants are "the largest thing in the Earth's mantle" and are essentially souvenirs from a very important event in geological and astronomical history.
Located respectively under West Africa and the Pacific Ocean, these LLSVPs continue to push the boundaries of some of the greatest minds in science. While we have some answers, the quest is far from over to understand everything about these giant cosmic rocks. Stay tuned for more of the Earth's greatest mysteries!