University Park, Pennsylvania – A new theory about the moon’s origin is challenging the commonly accepted narrative of its formation. For decades, scientists believed that the moon was created from debris following a massive collision between Earth and a small planet called Theia. However, recent research from Pennsylvania State University suggests a different scenario.
Professor Darren Williams and Professor Michael Zugger propose that the moon was captured by Earth during a close encounter with a binary system. Their study challenges the traditional idea that the moon resulted from a planetary collision, which has been the prevailing explanation for the moon’s origin since the 1984 Kona Conference.
One of the key unresolved questions about the moon’s formation is its unique orbit. If the moon had formed from a collision and coalesced into a ring around Earth, its orbit should align with the planet’s equator. Yet, the moon’s orbit is not in line with Earth’s equator but more aligned with the sun, raising doubts about the collision theory.
The binary-exchange capture theory suggests that Earth’s gravity separated the moon from a pair of rocky bodies in a binary system, with Earth capturing the moon while the other object drifted away. This theory finds parallels in the capture of Triton by Neptune, supporting the idea of capture events in the solar system.
Williams and Zugger’s calculations indicate that Earth could have captured a satellite even larger than the moon, potentially an object the size of Mercury or Mars. The moon’s elliptical orbit, initially influenced by tides on Earth, gradually evolved into a more circular orbit over thousands of years.
As the moon’s orbit became more circular and locked into its current state, it began drifting away from Earth due to gravitational interactions with both the sun and Earth. This slow drift explains the moon’s current distance of 239,000 miles from Earth and the competing gravitational forces acting on it.
While the binary-exchange capture theory offers a compelling alternative to the traditional collision theory, Williams emphasizes that the moon’s formation remains a subject of ongoing study and debate. The new theory opens up avenues for further research and exploration into the mysteries of the moon’s origin.