Is there any evidence for the claim that the moon was once part of the Earth?

Question

There is a hypothesis that says a part of the Earth was split away and became the Moon.Is there any scientific evidence for this claim?

Answer 1

Evidence:

1. Earth's spin and the Moon's orbit have similar orientations.
2. Moon samples indicate that the Moon's surface was once molten.
3. The Moon has a relatively small iron core.
4. The Moon has a lower density than Earth.
5. Other solar systems provide evidence of similar collisions.
6. Giant collisions are consistent with the leading theories of the formation of the Solar System.
7. The stable-isotope ratios of lunar and terrestrial rock are identical, implying a common origin. This refers, first, to oxygen isotopes, which are equally common on Earth and the Moon, a situation that indicates the Earth and the Moon were formed at about the same distance from the Sun. Oxygen isotope ratios, which are precisely measured, are unique for each body in our solar system. Also, rocks from the Moon contain more heavy isotopes of zinc, and less zinc overall, than similar rocks from Earth or from Mars. That is consistent with a prediction that zinc would have been depleted from the Moon as a result of evaporation, which in turn is an expected feature of an impact.

The Theia Impact Hypothesis or Giant Impactor Hypothesis is basically now the consensus view of how the Moon formed. Here it is, in a nutshell: About 4.45 billion years ago, Earth - quite a young planet then - was hit by another planetoid about the size of Mars, known as Theia. The collision released about 100 million times the energy released when the K-T asteroid struck our planet. The collision destroyed the rogue planetoid that had hit the Earth. It also probably vaporized the upper layers of Earth's mantle and ejected large amounts of debris into Earth orbit. That debris formed a ring around Earth and, eventually, the Moon formed from the debris.