The Supermoon of November 14, 2016 sets behind the Philadelphia skyline. The closest, brightest and biggest full Moon since January 26, 1948. These particular circumstances won't repeat again until until November 25, 2034. A Supermoon is when the Moon is both fully illuminated and at the same time near its closet point in its orbit around the Earth (perigee). Astronomers simply call this a perigee full moon. This Supermoon had an apparent diameter of 34 arcminutes, some 14 percent larger than a full Moon at apogee, when it is farthest away in it's orbit around the Earth.