A supermoon is a full moon that happens within 12 hours of the lunar perigree, or the point in the lunar orbit that brings the moon closest to Earth. The moon's orbit is slightly elliptical; at its closest approach, the moon is 225,622 miles (363,104 kilometers) from Earth. At its farthest, the moon is 252,088 miles (405,696 km) away.
The nearest full moon appears about 14 percent larger and 30 percent brighter than the full moon at its farthest point from the planet. But despite folklore to the contrary, the supermoon is not responsible for natural disasters, babies being born or people going mad.