Saturday's event is a "supermoon," the closest and therefore the biggest and brightest full moon of the year. At 11:34 p.m., the moon will be about 221,802 miles from Earth. That's about 15,300 miles closer than average.
That proximity will make the moon appear about 14 percent bigger than it would if the moon were at its farthest distance, said Geoff Chester of the U.S. Naval Observatory.