What causes the moon to change it size and what effect does this have on earth?

The moon circles the Earth on a schedule that is approximately 28 days. As it does so the relationship between the Earth and the Sun changes and sunlight shines on different parts of the moon's surface, giving it a different appearance from Earth. Just as the Moon is attracted to Earth by gravity, the Earth too is attracted to the Moon. The oceans are affected by the Moon and the water rises toward the Moon, giving us tidal variations.