Question

What is th current hypothesis on how the earths moon was formed?

Answer 1

The current accepted theory is known as the Giant Impact Hypothesis, where according to this NASA webpage "Origin of the Earth and Moon" (Taylor) a Mars sized object collided into the early Earth.

The prevailing theory supported by the scientific community, the giant impact hypothesis suggests that the moon formed when an object smashed into early Earth. Like the other planets, Earth formed from the leftover cloud of dust and gas orbiting the young sun.

Answer 2

The hypothesis is that around four and a half billion years ago, a mars-sized planetary object collided with the forming earth, merging the two masses at the expense of a massive amount of ejecta. This particulate ejecta, influenced by the local gravity, attracted together and formed the moon, locked tidally to the earth.