{"id":35648,"date":"2023-11-01T17:00:00","date_gmt":"2023-11-01T16:00:00","guid":{"rendered":"http:\/\/9290db39-3365-4179-a409-3d8b6695dd9a"},"modified":"2023-11-01T18:47:57","modified_gmt":"2023-11-01T17:47:57","slug":"scientists-discover-alien-planet-debris-buried-deep-under-earths-crust","status":"publish","type":"rss_feed","link":"https:\/\/c01.purpledshub.com\/bbcsciencefocus\/rss_feed\/scientists-discover-alien-planet-debris-buried-deep-under-earths-crust\/","title":{"rendered":"Scientists discover alien planet debris buried deep under Earth\u2019s crust"},"content":{"rendered":"

Long ago, an alien planet crashed into Earth \u2013 causing a collision so big the debris formed the Moon and left mysterious remnants lodged deep in the Earth\u2019s mantle. <\/p>

By Noa Leach\n <\/p>

Published: Wednesday, 01 November 2023 at 16:00 PM<\/p>

\n\n

Around 4.5 billion years ago, a massive collision with another planet changed Earth forever. Now, scientists have discovered that extra-terrestrial debris is still lodged inside our world<\/a>.<\/p>

For years, scientists have puzzled over anomalous seismic activity deep under the Earth\u2019s crust. There are two places where seismic activity has a mysteriously low velocity: one beneath the African tectonic plate, and the other under the Pacific tectonic plate.<\/p>

This activity impacts tectonic plate structures \u2013 and therefore changes everything from the formation of mountains<\/a> to the joining and splitting of supercontinents.<\/p>

The new study, published in Nature<\/em>, details how scientists at the California Institute of Technology, USA, and Shanghai Astronomical Observatory, China, ran computer simulations to solve this puzzle. These calculations involved high-resolution impact simulations, mantle convection models, mineral physics calculations, and seismic imaging.<\/p>

The scientists discovered that the material in these two low-velocity areas is 2-3.5 per cent denser than material in the surrounding mantle.<\/p>

Dense pieces of ancient protoplanet Theia have survived for 4.5 billion years in Earth’s mantle \u2013 explaining mysterious seismic activity 2,900 km (1,800 miles) below the crust. The same debris also forms the Moon. – Image credit: Hern\u00e1n Ca\u00f1ellas<\/figcaption><\/figure>

It\u2019s these pieces of material, tens of kilometres big, that they think are relics of an ancient protoplanet (a large body of matter orbiting around the Sun<\/a> or a star developing into a planet) known as Theia, now buried and preserved under the Earth\u2019s crust. The alien protoplanet was Mars<\/a>-sized when it crashed into proto-Earth, known as Gaia.<\/p>

The study found that Theia\u2019s shards actually form two per cent of the Earth\u2019s mass. The scientists think the alien material is so dense because it is enriched with iron \u2013 just like Moon rocks<\/a>.<\/p>

In fact, many scientists already believe that the Moon was formed by this collision with Theia. Earlier simulations suggested that the Moon was likely formed by the protoplanet\u2019s debris \u2013 making the composition of the Moon mostly alien material.<\/p>

These same simulations suggested that Earth was only lightly contaminated with pieces of Theia, given that little direct evidence of Theia exists.<\/p>

But the new study challenges this idea \u2013 showing instead that the impacts on Earth were significant.<\/p>

\u201cThe Moon-forming giant impact\u201d, said one of the paper\u2019s authors Professor Deng Hongping<\/a>, instead \u201cmarks the starting point for the Earth\u2019s geological evolution over the course of 4.5 billion years.\u201d<\/p>

Because they are so dense, the shards of Theia likely sunk towards the Earth\u2019s core and melted into dense blobs. This sinking created the low-velocity areas that have helped to form the Earth as we know it.<\/p>

The findings could help us learn more about the formation of the Earth, Moon and exoplanets beyond our solar system.<\/p>

Read more:<\/strong><\/p>