I have seen the Moon countless times and have never wondered how it was formed, until today!
Three theories have been on the table, debated all around the world, but I find this one the most fascinating: Theia was a planet about the size of Mars that existed in the solar system 4.5 billion years ago. Astronomers believe that this planet collided with the earth – computer simulations of this “late-impact” scenario suggest an impact angle of about 45° and an initial impactor velocity below 4 km/s.
Obviously the impact would have been so great that Theia’s iron core would have sunk into the young Earth’s core, and most of Theia’s mantle mixed with the Earth’s mantle. However, a significant portion of the mantle material from both Theia and the Earth would have been shot into orbit around the Earth due to the massive impact.
The material then orbited around the Earth so quickly that it accumulated into the Moon, much like a snowball collecting more and more material with each orbit and increasing with size.
And so they say the impact craters seen on the moon surface is clear evidence of this event – a collision that is known as the “Big Splash”.