For many this could be a once in a lifetime Supermoon, given that the last one of this magnitude was in 1948 and the next in 2034.
It all has to do with the fact that the Moon’s closest approach to Earth is NOT constant each month. It is closer to Earth some months than others. Multiple factors influence this, including the Sun’s gravitational pull.
Plus, a Supermoon is NOT an astronomical term. It is more a lay term and as such there is latitude in what is considered ‘closest’ to Earth. In any given month, for it to be a Supermoon the moon doesn’t even have to be at its closest point to the Earth for that month. It only has to be within 90% of the closest approach.
Hence why all Supermoon’s are not equal.
So the November 14, 2016 will be 229 miles (0.10%) closer to Earth than the September 2015 Supermoon.
I just hope we have good weather that night.