There are many theories that try to explain how the Moon was formed. ‘The Impact Theory’ is a popular one among them. This theory suggests that the Moon is younger than the Earth though it is billions of years old.
The Impact Theory talks about something that happened about 4.5 billion years ago. Back then, the Earth did not have any satellites. A huge body about the size of Mars hit our planet. This shook off the Earth from its orbit as a result of which, portions of the Earth broke.
Gradually, these broken pieces came together along with gas and dust, and solidified to form the Moon. This unification had other effects however; molten lava oozed out from the interior of the Moon for the next two billion years.
Picture Credit : Google