As you can see by this picture, the unicorn is attempting to bite the moon. That is because unicorns are addicted to light, and so instinctively, they eat their light source at nighttime. This is a Rare Shiny Sparkly White Unicorn, of which there are only 2 left in the world(and in never land).

How You Can Help
You can report them to animal control if you see them in the wild. DO NOT SHOOT AT THEM. This is highly normal to see a mythical creature, as long as you are having regular visits with your psychiatrist. You are very lucky to have seen the world's rarest creature. CASE CLOSED.