How was the moon formed?

The most widely accepted theory of how the moon was formed is the Giant Impact Hypothesis. According to this theory, the moon formed from debris created by a collision between Earth and a Mars-sized body, often referred to as Theia, early in the solar system's history, about 4.5 billion years ago.

During this collision, a large amount of material was ejected into space, which eventually coalesced into the moon. The collision would have been so violent that it would have melted both Theia and Earth, and the newly formed moon would have been covered in a molten layer of rock.

Over time, this molten layer cooled and solidified, and the moon took on the shape we recognize today. Evidence for the Giant Impact Hypothesis comes from the similarities between the moon and Earth's crust, the fact that the moon is depleted in volatile elements, and the presence of moon rocks that have been dated to around the time of the collision.