A lunar phenomenon is an event that occurs on the moon. A CORONA is a HALO of light around the moon caused by the refraction of sunlight through ice crystals in the atmosphere. A HALO is a ring of light around the moon caused by the reflection of sunlight off of ice crystals in the atmosphere. An ECLIPSE is an event where the moon passes between the Earth and the Sun, blocking out the Sun's light. A moonset is when the moon sets below the horizon. A TIDE is the rise and fall of the ocean's water level due to the gravitational pull of the moon and sun.