The space smash that helped lead to the formation of the Moon as we know it, also left alien “blobs” deep inside the Earth, says a new study.
For decades, it has been believed that the Moon was formed when a small planet smashed into the proto-Earth, around 4.5 billion years ago. The detritus of this impact flew off into space, with a sizeable portion being kept in our planet’s orbit, and eventually forming into the familiar natural satellite.
The impacting planet was thought to be around the size of Mars, and was named Theia, and it left Earth with a “buried planet”, according to a new study’s author, published in the journal Nature. These two alien "blobs" may have been releasing galactic elements into the Earth ever since.
Theia could have been formed in the far-reaches of the galaxy, before being dragged Earth-wards by the influence of Jupiter or Venus' gravity, leading to the impact. The “buried planet” it caused was discovered using seismology instead of telescopes, looking deep into the Earth to learn more about what was happening, and has happened, out in the stars.
The continent-sized alien "blobs" have long been known of, and exist under the Pacific Ocean and Africa. However, previously they were assumed to have been created during Earth’s differentiation - the process that led to the many layers of the Earth. However, Qian Yuan of Arizona State University’s new study suggests that a significant amount of material from Theia found itself to the forming Earth, becoming a part of the planet.
This is in the shape of large low-velocity provinces (LLVPs) which are thousands of miles long and sit at the base of the mantle, just above the Earth’s core. Using state of the art simulations to recreate those pivotal moments billions of years ago when Theia and the proto-Earth collided, they discovered that in the aftermath, there was a two layered mantle system made from the remains of both.
Whilst the upper half fully melted, the lower half remained solid and also captured around ten per cent of Theia’s material, Qian Yuan said. This is a mass close to the current “blobs”. The theory is supported by the fact that the LLVPs contain “primordial volatiles”, gases that appeared to predate the impact, which could have come from Theia as it raced towards the Earth, through space.
Similarly, it might also explain the existence of galactic elements, hailing from space, that are found in some volcanic rocks on Earth - having risen up through the Earth’s crust. Qian Yuan said: “We've identified a new astronomical object, 'Buried Planet', using SEISMOLOGY, rather than telescopes. It's a survivor of Theia, the planet that collided with Earth 4.5 billion years ago to form our Moon.”