What happened
For decades, the leading theory of the Moon's origin held that a Mars-sized body called Theia struck the early Earth about 4.5 billion years ago, ejecting debris that coalesced into the Moon.
New computer simulations, however, indicate that such a giant impact could have produced a fully formed Moon in less than five hours, offering a fresh pathway for lunar formation.
Why it matters
This rapid-formation scenario challenges the traditional model, which often required a slower accumulation of debris over a longer period.
If confirmed, it could reshape our understanding of how the Moon and other planetary satellites form, and provide new constraints on the early Earth-Moon system.
Key facts
The impact occurred roughly 4.5 billion years ago.
The impacting body was about the size of Mars, named Theia.
The new simulations show the Moon could form completely within five hours after the impact.
What to watch next
Future studies may test these simulations against lunar samples to see if they match the Moon's composition and orbital characteristics.
Researchers might also explore whether similar rapid-formation processes could explain the origins of other moons in the solar system.