Moon's origin: a surprising discovery challenges the most widely accepted theory.

The Moon has been Earth's natural satellite for over 4 billion years. The most widely accepted theory suggests that the Moon formed as a result of a catastrophic collision between our planet and a Mars-sized protoplanet named Theia. However, a new study published in the journal PNAS challenges this long-standing theory, as reported by Interesting Engineering.

The new research focused on investigating the origin of the Moon and the emergence of water on Earth. Scientists discovered additional clues about how the Moon was formed and how our planet first acquired water.

Researchers conducted a new analysis of oxygen isotopes in lunar and terrestrial rocks. Isotopes are variations of the same chemical element, with atoms that have different masses. The scientists employed an advanced "laser fluorination" technique, which involves using a laser to extract oxygen from rock samples.

The measurements revealed a surprisingly high similarity in the content of oxygen-17 isotopes between rock samples from both Earth and the Moon. However, the isotopic composition should differ, as it is believed that the Moon should have a different isotopic makeup due to the involvement of the protoplanet Theia in its formation.

The authors of the study concluded that the Moon likely formed primarily from material in Earth's mantle with minimal contribution from the protoplanet Theia. The researchers believe that Theia lost its rocky mantle during earlier collisions with other bodies and then collided with early Earth as a metallic core. Thus, Theia could have become part of Earth's core, and the Moon formed from the ejected material from our planet's mantle. This explains the remarkable similarity in the composition of Earth and the Moon.

Additionally, the scientists gathered some clues regarding how water arrived on Earth. The popular theory suggests that water reached Earth after the Moon's formation during later periods in the planet's history. This theory posits that a series of water-rich meteorite impacts delivered vast amounts of water to Earth.

The study indicated that many types of meteorites can be excluded as sources of water on Earth. The results support another theory, which suggests that water may have reached Earth during the early stages of its formation.

Researchers concluded that most of the water on Earth during its earliest history was delivered by enstatite chondrite-class meteorites.