## Can any one tells how many types I will Resolve this question ...

Occasional Contributor
Posts: 15

# Can any one tells how many types I will Resolve this question ...

Given that July 9, 1998 is a full moon, andI

there are 29 days between full moons, in what months will the next

few blue moons occur?

Super User
Posts: 23,662

## Re: Can any one tells how many types I will Resolve this question ...

There isn't always 29 days between full moons.

Occasional Contributor
Posts: 15

## Re: Can any one tells how many types I will Resolve this question ...

but my question is simple is that will a program resolve this question ........:smileysilly:

Super User
Posts: 23,662

## Re: Can any one tells how many types I will Resolve this question ...

Only if you know the exact time of one full moon, because of the partial day.  Then assuming the maths correct yes, but I think there's some other factors that are missing

SAS Super FREQ
Posts: 9,365

## Re: Can any one tells how many types I will Resolve this question ...

In fact, according to the Wikipedia article, the lapse is 29.53 days:

"Origin

One lunation (an average lunar cycle) is 29.53 days. There are about 365.25 days in a solar year. Therefore, about 12.37 lunations (365.25 days divided by 29.53 days) occur in a solar year. In the widely used Gregorian calendar, there are 12 months (the word month is derived from moon) in a year, and normally there is one full moon each month. Each calendar year contains roughly 11 days more than the number of days in 12 lunar cycles. The extra days accumulate, so every two or three years (7 times in the 19-year Metonic cycle), there is an extra full moon. The extra moon necessarily falls in one of the four seasons, giving that season four full moons instead of the usual three, and, hence, a blue moon."

See the full Wikipedia article here: Blue moon - Wikipedia, the free encyclopedia and the Wikipedia article on Full moon has the math for calculating full moons.

cynthia

Occasional Contributor
Posts: 15

## Re: Can any one tells how many types I will Resolve this question ...

Yups Right Cynthia ...

Can you help to resolve using SAS program ???

SAS Super FREQ
Posts: 9,365

## Re: Can any one tells how many types I will Resolve this question ...

Hi:

The program is going to be simple math, BUT only if there were enough information. For example, in just calculating the difference between known full moons for 2012, the difference is not a constant 29.53, these differences (based on GMT times for the known full moons in 2012) are shown if you run the program below. So, instead there must be some other factor coming into play. The Wikipedia article on full moons  (Full moon - Wikipedia, the free encyclopedia) suggests that because the moon does not have a true circular orbit, that a correction factor has to be applied. If I had the time, it would be an interesting problem. But it seems to me that you're only going to get as far as the correct day if you adjust by 29.53, which for most months would be good enough. But when the full moon is close to midnight, then the "fudge factor" is going to make a difference, so to solve this, you need a formula that will adjust to the minute (or second), accounting for the non-circular orbit of the moon.

Hope this helps. Here are some links I found useful.

http://www.nevis.columbia.edu/~seligman/moontables.html

http://www.moongiant.com/full_moon_calendar.php

http://www.voidware.com/moon_phase.htm

cynthia

data gmt_full_moon;
infile datalines;
input thismonth : datetime15.  lastone : datetime15.;
diffsec = thismonth-lastone;
numday = diffsec / 86400;
/* 86400 seconds in 1 day */
return;
datalines;
09jan2012:07:32 10dec2011:14:37
07feb2012:21:56 09jan2012:07:32
08mar2012:09:42 07feb2012:21:56
06apr2012:19:20 08mar2012:09:42
06may2012:03:36 06apr2012:19:20
04jun2012:11:12 06may2012:03:36
03jul2012:18:52 04jun2012:11:12
02aug2012:03:27 03jul2012:18:52
31aug2012:13:58 02aug2012:03:27
30sep2012:03:19 31aug2012:13:58
29oct2012:19:51 30sep2012:03:19
28nov2012:14:47 29oct2012:19:51
28dec2012:10:23 28nov2012:14:47
;
run;

ods listing;
proc print data=gmt_full_moon noobs;
title 'Number of Actual Days Between Full Moons';
title2 'Based on GMT';
format thismonth lastone  datetime20.;
run;

Results from the program showing difference between full moons in GMT:

Number of Actual Days Between Full Moons

Based on GMT

thismonth               lastone       diffsec     numday

09JAN2012:07:32:00   10DEC2011:14:37:00  2566500    29.7049

07FEB2012:21:56:00   09JAN2012:07:32:00  2557440    29.6000

08MAR2012:09:42:00   07FEB2012:21:56:00  2547960    29.4903

06APR2012:19:20:00   08MAR2012:09:42:00  2540280    29.4014

06MAY2012:03:36:00   06APR2012:19:20:00  2535360    29.3444

04JUN2012:11:12:00   06MAY2012:03:36:00  2532960    29.3167

03JUL2012:18:52:00   04JUN2012:11:12:00  2533200    29.3194

02AUG2012:03:27:00   03JUL2012:18:52:00  2536500    29.3576

31AUG2012:13:58:00   02AUG2012:03:27:00  2543460    29.4382

30SEP2012:03:19:00   31AUG2012:13:58:00  2553660    29.5563

29OCT2012:19:51:00   30SEP2012:03:19:00  2565120    29.6889

28NOV2012:14:47:00   29OCT2012:19:51:00  2573760    29.7889

28DEC2012:10:23:00   28NOV2012:14:47:00  2576160    29.8167

Occasional Contributor
Posts: 15