Answer:
The moon is not actually white, it's grey.
Step-by-step explanation:
What I learned is that what makes it white is the reflection of the sun and the sun makes it glow, that's why it looks white.
And if you focus on the moon when it's not full you'll see the other part of it showing but it looks grey not white, because as I told you it's the suns reflection.
Hope I helped!
Have a good day. =)