The Earth may have developed around an alien rock core

In the Earth's core there may be an alien rock core: the new theory on how our planet was formed

The Earth formed about 4 and a half billion years ago, from a disc of rotating dust and gas that settled into larger and larger agglomerations consisting of rock, gaseous materials and radioactive elements. Thus were born what would become the planets of the Solar System.

The Earth then appeared as a sphere of molten incandescent materials, which only after cooling divided into the core, mantle and crust. As for water, there is still no unequivocal position by the scientific community: it could have formed on site or arrived on Earth from elsewhere, as it was.

The origins of the Earth

The Earth originated thanks to the collisions that affected the first celestial bodies that were formed in the Solar System from a disc of rotating gaseous materials.

Not much is known about the nature of the material from which the planet was born: its composition would be impossible to trace even if we were able to get to the core of the Earth.

Where did the original material from which our planet was formed come from? That's the question Amaya Moro-Martín and Colin Norman, of the Telescope Science Institute in Baltimore, are trying to answer.

The newly published study starts with an important finding of recent years: as demonstrated by the passage of 'Oumuamua in 2017 and Comet Borisov in 2019, celestial objects can pass through our solar system.

This means that many other objects from distant galaxies may have traveled around and into our system in the past. And that they may have played a role in the birth of the galaxy's solar systems.

If 'Oumuamua and Borisov passed between the Sun's planets without stopping, it's because the Sun is a "mature" star, traveling at a speed that doesn't allow space-dispersed material to aggregate around it, as it did when it was a much younger star.

A core of alien material

To investigate the possibility that Earth originated from a core of alien material, Moro-Martín and Norman estimated how many objects can be trapped inside a young star.

In a 10-million-year period, 600 billion objects about the size of a meter, 200 million clusters 10 meters large, 60,000 100-meter objects and about 20 objects larger than a kilometer can be captured.

"We don't really know how many objects there are out there," says Moro-Martín, "but the numbers are pretty high," and they seem to suggest that interstellar objects may indeed be a "seed" in the constitution of planets.

These in fact form thanks to an accumulation of matter that is generated by the fusion of so-called "pebbles" or by collision with celestial bodies of the type of asteroids; how from a disc of rotating materials one arrives at objects as large as planets is to date still an open question.

Attracting the solar system, interstellar objects as large as 'Oumuamua or Barisov could have acted as condensation nuclei.

This means that the Earth itself could be the result of the passage of an interstellar object, which could have lingered near the protoplanetary disk of the Sun, thus making possible the accumulation of materials from which originated our planet.