The supermoon occurs when the moon becomes full at the closest point in its orbit to Earth, called a perigee full moon. Although there has already been a supermoon earlier this year on July 12, this one will be particularly striking. It will become full at the same time as its perigee, making it the most super of the supermoons this year. The moon is expected to appear 12% bigger and 30% brighter than it did in January 2014, when the moon was full at the farthest point.