Read something VERY interesting about our Moon.
The leading theory as to how the Moon was created involves a theory in which the Earth was hit by a Mars-sized body and in the ensuing aftermath the material thrown out form booth bodies ultimately formed into our Moon. Known as the "Big Splat" this theory has been the leading idea as to how our Moon came to be.
Recent research into the Apollo lunar samples has thrown a curve ball at the Big Splat. The researchers concentrated on comparing the amount of titanium isotopes found in Apollo lunar samples and meteorites to the amounts found on Earth. What they found was that the amount found in the lunar samples was the
"The Big Splat"
Image Copyright Nova Celestia
same as Earth's; the meteorites were significantly different. Just like each of us has DNA that can be traced back to each of our parents, the researchers were looking for two different traces of titanium isotopes in the Apollo lunar samples - they only found one.
Now there are possible explanations for this finding such as the collision involved an ice only world that contained no titanium but that is highly unlikely as we have not found any objects like that in the solar system. Or there may have been some dynamics that deleted the titanium from the other body due to the collision - again not thought to be very likely.
The bottom line is that we still do not know for certain, even 40 years after Apollo, how our planet's companion was made.
Sky Guy in VA