A supermoon is the coincidence of a full moon with the closest approach to Earth on its elliptical orbit resulting in the largest apparent size of the lunar disk. The technical name is the "Perigee-Syzygy of the Earth-Moon-Sun system".
The most recent occurrence was on 23rd June 2013 and the next is anticipated on 10th August 2014. Supermoons occur approximately once every 14 full moon cycles.
A Bell 47 over East Rutherford in the state of New Jersey, North America as seen on 22nd June 2013 (Photo: Julio Cortez)