This May’s full Moon is a "super Moon,” as much as 14% bigger and 30% brighter than other full Moons of 2012.
The scientific term for the phenomenon is "perigee moon." Full Moons vary in size because of the oval shape of the Moon's orbit. The Moon follows an elliptical path around Earth with one side ("perigee") about 50,000 km closer than the other ("apogee"). Full Moons that occur on the perigee side of the Moon's orbit seem extra big and bright.
Such is the case on May 5th at 11:34 pm Eastern Daylight Time when the Moon reaches perigee. Only one minute later, the Moon will line up with Earth and the sun to become brilliantly full. The timing is almost perfect.