How did the Moon form? There is a new origin story

Earth gained a temporary mini-moon for a period of two months, but the origin story of our very own Moon remains a mystery.
For decades, scientists believed the Moon formed from debris after a collision between a young Earth and another celestial object. However, new research from Penn State University suggests an alternative origin story that could revolutionise our understanding of lunar formation.
In a study published in The Planetary Science Journal, Professor Darren Williams and senior research engineer Michael Zugger propose that the Moon may have been captured during a close encounter between Earth and a terrestrial binary system.

This binary-exchange capture theory offers a fresh perspective on a question that has puzzled scientists since the Apollo missions brought back lunar samples in the early 1970s.
The prevailing theory, established at the 1984 Kona Conference, has dominated scientific thought for 40 years. However, it fails to explain certain aspects of the Moon’s orbit.
Williams points out that if the Moon formed from collision debris, it should orbit above Earth’s equator. Instead, its orbit aligns more closely with the Sun than Earth’s equatorial plane.
The researchers’ new model suggests that Earth’s gravity could have separated a binary pair of rocky objects, capturing one to become our Moon. This scenario could account for the Moon’s current orbital characteristics.
Williams and Zugger’s calculations demonstrate that Earth could theoretically have captured a satellite even larger than the Moon, potentially up to the size of Mars. However, they note that such a large capture might have resulted in an unstable orbit.

The study also addresses how the Moon’s orbit evolved over time, influenced by tidal forces. Initially captured in an elongated elliptical orbit, the Moon’s path gradually became more circular, eventually locking into its current configuration.
While this new theory provides a mathematically plausible alternative to the collision hypothesis, Williams emphasizes that the Moon’s true origin remains uncertain. “No one knows how the Moon was formed,” he stated. “For the last four decades, we have had one possibility for how it got there. Now, we have two.”
This research opens up new avenues for lunar studies and demonstrates that even long-held scientific theories can be challenged by innovative thinking and rigorous analysis.
As our understanding of celestial mechanics continues to evolve, the mystery of the Moon’s origin may finally be unraveled.