(So if we all agreed to not look at the moon it would not exist? Really?)
If have no subject to know what is a moon, it would not exist.
What is an object without an observer? Certainly the objects share many universal traits, but they have some traits who just an subject can perceive in a unique way. This trait are located in the object itself?
Materialism is like classical mechanics, it are very useful in a way, but it can't explain the subject.