According to scientists the moon was created when an object as big as the planet Mars smacked into the Earth billions of years ago. Debris were splited and started to move in orbit of earth,later they consolidated to form the moon.
The Astrophysical Journal reports that just 5-10% of planetary systems in the Universe have moons created this way. Huge dusts were created in this collision and later consolidated. But this type of collision occur rarely because huge dusts are not seen around the stars. The age of moon is calculated equal to that of our sun.