Was there ever a collision of Earth with the hypothesized planet of Theia, which gave birth to the Moon? There is compelling evidence, such…

Was there ever a collision of Earth with the hypothesized planet of Theia, which gave birth to the Moon? There is compelling evidence, such as measures of a shorter duration of the Earth's rotation and lunar month in the past, that suggests the possibility that Earth's Moon was much closer to Earth during the early stages of Solar System formation.

Open the “Early Earth and the Solar System” section on Wikipedia →

Source: List of unsolved problems in geoscience (CC BY-SA 4.0)