Super perigee Moon on May 5-6

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.

A ScienceCast video explains the facts and fiction of "super-moons." Credit: Science@NASA

Such is the case on May 5th at 11:34 pm Eastern Daylight Time when the Moon reaches perigee, the point in the Moon's elliptical orbit closest to Earth. Only one minute later, the Moon will line up with Earth and the sun to become brilliantly full.

Super perigee Moons are actually fairly common. The Moon becomes full within a few hours of its closest approach to Earth about once a year on average. The last such coincidence occurred on March 19th, 2011, producing a full Moon that was almost 400 km closer than this one. 

Source:

• Perigee "Super Moon" On May 5-6, Science@NASA, May 2, 2012.