Continents on Earth May Have Formed Thanks to the Milky Way - Study

Scientists have proposed a hypothesis that the formation of continents on Earth could be linked to the Solar System's movement through the spiral arms of the Milky Way. As it crossed the arms, gravity ejected icy objects from the Oort Cloud, which collided with the young Earth and contributed to the formation of continental crust. Analysis of isotopes in zircons confirms a correlation between crust formation stages and periods of passing through the arms.

Scientists have proposed a hypothesis that the formation of continents on Earth could be linked to the Solar System's movement through the spiral arms of the Milky Way. Immediately after its formation over 4.5 billion years ago, Earth was a hot ocean of molten rock. After several hundred million years, the surface began to cool, and solidified areas formed the first landmasses. Traditionally, this process was explained by internal geological mechanisms, but new research suggests an external influence. The Solar System orbits the galactic center every 250 million years and crosses the spiral arms—regions with high concentrations of gas and dust—approximately every 150–200 million years. When passing through the arms, gravity could eject icy objects from the Oort Cloud toward the Sun. Colliding with the young Earth, they likely contributed to the formation of the first stable areas of continental crust. Traces of events over 4 billion years ago have almost disappeared, but they are preserved in the mineral zircon. Analysis of hafnium and oxygen isotopes in these crystals allowed researchers to reconstruct the stages of crust formation. They compared isotopic data with periods of passing through the arms and eras of asteroid bombardment and found correlations. The hypothesis is not yet confirmed, but scientists do not rule out that the structure of the galaxy could have played a role in the emergence of continents.