Planetary scientist James O'Donoghue talked about two ways to measure the length of the day on our planet and explained why we eventually chose the longest.
Where did such a massive body as the Moon come from near our planet, why it and the Earth have such orbital parameters, as well as the composition of rocks explains the hypothesis of a giant collision. Approximately 4.5 billion years ago, another protoplanet the size of Mars crashed into the embryo of the Earth: the video shows a simulation of this process.