What is the most popular idea about how the moon formed?

Since the 1970s, the 'Giant Impact' theory has suggested that a Mars-sized object named Theia smashed into Earth around 4.31 billion years ago, knocking a huge cloud of debris into space which eventually coalesced to form the Moon. A new theory suggests the moon may have formed through the merging of 20 smaller 'moonlets' following asteroid strikes on the young Earth.

Asked by Pamela Ferdinand · Last updated 5 years ago · 455K views