If you like to stargaze you need to be on the lookout tomorrow night at exactly 8:34 PM Eastern for the Supermoon. Supermoons happen on occasion when the moon is full and at its closest point in orbit the earth. The last time this happened was on March 19, 2011.
The official name is the perigee moon and this is the closest the moon will be to the earth this year. With the moon closer to the earth, people who live in coastal areas can expect higher than normal and lower the normal tides. The moon will not cause volcanoes or anything like that.
The supermoon this year will be a tiny bit smaller than the Supermoon from last year. This year the moon will be about 50,000 miles closer to the Earth than it is when it's at its furthest point in its orbit. This will make the moon appear 14% larger and about 30% brighter than most full moons.