Theia: The Alien Planet Inside Earth
It is hypothesized that inside the Earth, there is a remnant of the planet that once hit the young Earth.
Have you ever wondered where the Moon came from?
According to a popular theory, the Moon was formed from the debris of a giant collision between the early Earth and a Mars-sized planet, about 4.5 billion years ago. This planet is called Theia, after the Greek goddess who was the mother of Selene, the goddess of the Moon.
But what happened to Theia after the impact? Did it completely vaporize or escape into space? Not quite. Researchers from the University of Minnesota have found evidence that Theia is still inside Earth, hiding in its mantle.
How did they discover this? Well, about four decades ago, a geophysicist named Adam Dziewonski used a technique called seismic tomography, which is like an ultrasound of the Earth’s crust, to map its tectonic structure. He found a blob, a region that was more dense, hot, and iron-rich than the surrounding mantle, under Africa. Another blob under the Pacific Ocean was detected later, in 1996, by another geophysicist named Don Anderson. Both blobs are now considered to be large low-velocity provinces (LLSVPs), and they are among the largest and most mysterious features in Earth’s mantle.
