The answer is that scientists have found that wolves’ howling doesn’t actually have very much (if anything) to do with the moon. Most likely, the reason we associate the howling with the moon is that wolves are more active on bright, clear nights, so we mostly hear them howling on nights when we can also see the moon. It’s probably just a coincidence that the two so often occur together!
In truth, most researchers have found that wolves’ howling is much more about communicating with each other. Howls are used by wolves to say many things – they can express happiness, loneliness, or can be a way of letting other wolves know where it is at! And even though they’re most famous for howling, wolves can also bark, yelp, growl, and whimper!