(WHSV-TV3) A super moon happens when you have a full moon close to what's called perigee. Perigee is when the moon is at it closest approach to the earth. (Apogee is when it's farther away from the earth)
The supermoon can happen any time of the year.
This year, it's just coincidence that it is happening near the summer solstice, which happens to be the shortest night of the year.
The super moon is bigger and brighter than normal full moons, and it is about 12 percent larger than normal.
The moon will be some 29,000 miles closer to Earth than the farthest point in its orbit.
Michelle Thaller is a Scientist with NASA and says, "The full moon always looks best when it's just rising, just coming up above the horizon,. It seems larger even though it's not actually physically larger, it looks bigger. The moon is not going to change significantly over the course of Saturday night. The actual moment of the Supermoon is 7:30am Sunday morning."
However, by then, the moon will have already set. for us, so make sure you head out Saturday evening for the best viewing opportunity, and look in the east sky.