A "supermoon" is a term used to describe a full moon that appears larger and brighter in the sky. This happens because the moon is closer to Earth than usual during its orbit. Full definition
While we're on a nice streak of supermoons — there was one last month and we'll have another one in December, this month's will be extra spectacular because it becomes full within two hours of perigee — and thus will appear as the superest in decades. (treehugger.com)
A blue moon (you've heard «once in a blue moon» before) is when there are two supermoons in a calendar month. (relevantmagazine.com)
On November 14, we'll see the largest supermoon rise since 1948. (nrdc.org)