Welcome to DU!
The truly grassroots left-of-center political community where regular people, not algorithms, drive the discussions and set the standards.
Join the community:
Create a free account
Support DU (and get rid of ads!):
Become a Star Member
Latest Breaking News
General Discussion
The DU Lounge
All Forums
Issue Forums
Culture Forums
Alliance Forums
Region Forums
Support Forums
Help & Search
On Average, the Harvest Moon Occurs on Friday the 13th Every 210 Years.
For areas west of the Eastern Time zone, today is a very rare occurrence (once every 210 years on average) of the Harvest Moon beaming on Friday the Thirteenth.
The frequency of the harvest moon falling on "Friday The Thirteen" is easy to calculate. You can start by observing that the chance of the full moon falling on the thirteen of any month is about one in 30, or once every 2.5 years. Narrowing the day of the week to Friday means multiplying 2.5 by 7 which yields 17.5 years. Narrowing the month to September means multiplying 17.5 years by 12 which yields 210 years.
4 replies
= new reply since forum marked as read
= new reply since forum marked as read
I hope to have clear skies tomorrow night so I can get some photos.
Thank you for doing the arithmetic! I am lousy at that. 
