Full moon

A Moon is not a star but a planet. It has no natural light it radiates. The light people see at night, the moon light is just a reflection of sun light. So, the moon light is a reflection of light sun radiates. When it is night on the one side of the Earth it is a day on another side. Depending on the position of the sun on the opposite side of Earth we see the moon light.
So, the intensity of moon light depends on the position of sun. That same position of the sun is a reason for why we see half moon or full moon at night. According o scientific point of view the full moon is a time when the difference of celestial longitudes of sun and moon is equal to 180 degree. In other words, it is a time when Sun, Moon and Earth are situated in the straight chain.
When those three celestial bodies are situated like that the Moon is an opposition against Sun. so, the sun light brightens one side of the Moon and Moon is situated in the way so we can see the bright side of it. We can't see Moon as a planet, we see it as huge shining disk, and that disk we call full moon. It is the scientific point of view, but there is another one – supernatural.
It is common for people from the very beginning of the world to provide the period of full moon with different mysterious abilities and features. It was common to consider that some people are called by moon and when it is a full moon they follow the call of a moon. There are also stories about different monsters and creatures that become aggressive and wild during the full moon.