Lunar phases are the views of the moon as the suns light is reflected off it. During the day the moon will move, reflecting the light off the moon in a different direction. The reason why we can see the moon at night, is because we can see the reflection of the suns light. A full moon happens when the sun is on the opposite of the sun, and the light is being reflected down from the moon onto Earth. Lunar eclipses have everything to do with the position of the sun and where the moon is reflecting the light from.