A hypothetical, Mars-sized planet might have collided with Earth about 4.5 billion years ago and birthed the moon. The impact could have kick-started subduction on Earth, researchers suggest.
Tobias Roetsch/Future Publishing via Getty Images
A hypothetical, Mars-sized planet might have collided with Earth about 4.5 billion years ago and birthed the moon. The impact could have kick-started subduction on Earth, researchers suggest.
Tobias Roetsch/Future Publishing via Getty Images