The Math Genius Is Working On That

Yesterday I asked the question “How rare is today’s event?” How often does the 13th fall on a Friday? How often does a Full Moon fall on a Friday? How often does a Full Moon fall on a Friday the 13th?

According to my Moon Phase Pro (yes there’s an app for that):
In the next 260 weeks: (approx. 5 years from January 1, 2014 to December 31, 2019)
There are 11 Friday the 13ths.
There are 11 Full Moons that fall on a Friday.
There is 1 Full Moon that falls on Friday the 13th.

On Friday the 13th of January 2017 the full moon will be just past full, 98% full to be exact. Close, but not officially a full moon day which will be January 12th. So we can’t count that one.

The Next Full Moon Friday the 13th will be in August 2049. According to Space.com

Ok, great but I want to know how rare this really is. That requires a lot more math than I know. So I asked my local math genius. Continue reading →