cheker request GC5GMXT

Question

TO FIND 1 CACHE AT A FRIDAY THE 13 BY FULL MOON

Comments

I wonder how many Friday the 13th the last 5 years have had a full moon. :)

---

Is the moon phase the same at the same time all over the world? Say, if there is a full moon in Europe it will also be full moon in the US?

---

It probably depends on the definition of a full moon. The one on http://en.wikipedia.org/wiki/Full_moon uses the earth axis as a reference so on that one it is a yes. The full moon is a precise moment and not a day

On which calendar day day the full moon occur depend on where you are on the earth. The problem in creating this checker i to get the timezone a cache is located in

---

This have happend once the last five years. 13 June 2014. However, there are other fridays 13th that are close to the full moon soo that it looks like full moon.

---

According to http://moongiant.com/full_moon_calendar.php the full moon on June 13 was on 4:14 GMT on timezone  (GMT -5) the full moon was on June 12 ie the US

---

Friday the 13th occurs on average once every 7 months. Full moon occurs on the 13th of the month on average every (approx) 29.5 months. These two co-occur on average every (approx) 207 months, or roughly once every 17 years.

If we account for timezones, it works out as being on average roughly 8 years between co-occurrences that are achievable anywhere in the world.

The next four times it is possible anywhere to achieve this are:
January 2017 (only on a couple of Pacific islands that are UTC+13 or above)
September 2019 (in the Americas, at UTC-5 or below)
May 2033 (on a couple of Pacific islands at UTC-11 or below)
August 2049 (most of the world, at UTC-9 or above)

Ouch. I'd rate this one above the 4.5 difficulty it's been given.

Answer 1

I've created a checker based on my timezone counter script. I've tagged it with the eight possible dates (and appropriate timezones) from 2000 to 2050.

http://project-gc.com/Challenges/GC5GMXT/13840