Question

Why does the moon appear as a full circle even though it's not?

Answer 1

"Half Moon" simply refers to that moment in the lunar cycle haflway between the New Moon and the Full Moon. It doens't necessarily refer to the way it looks like.

Answer 2

Well it don't just disappear when its in its other stages other than full moon. Brightness of sun on part of the moon that you can see carries over to the dark parts. Making it so you can barely make out the outline of the rest of the moon.

Answer 3

Probably light reflected off the earth being reflected off the moon back to earth. I think it's called "earthshine."

Answer 4

Because it is a full circle. Sometimes it just doesn't look like it.