4.5 billion years ago the Earth actually had no moon. So where did our moon come from?
A cataclysmic event gave Earth our favorite satellite. Another planet, the size of Mars, drifted into the path of Earth. However, it did not collide directly with Earth. The huge object hit Earth only with a glancing blow. Still, the impact was so great that a mass of liquid rock was thrown into orbit. The material coalesced eventually into a ball and the moon was formed. When the moon was young, it was a spectacular molten sphere, burning brightly in the sky.