Interestingly, the term Supermoon is not used within the astrological community. The more scientific name for a Supermoon is a Perigee Moon. Perigee means the point at which the Moon is closest in its orbit to the Earth. Even more technically, a Supermoon is the perigee-syzygy of the Earth-Moon-Sun system. Syzygy is when the Earth, the Moon and the Sun are aligned, which happens at every Full Moon or New Moon. Got it? The result is that a Supermoon can be regarding as the coincidence of the two, although they do not perfectly coincide each so. So, some Supermoons are bigger than other Supermoons.