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 Subject: Variability of the month Category: Science > Astronomy Asked by: lochias-ga List Price: \$15.00 Posted: 21 Jun 2005 12:10 PDT Expires: 21 Jul 2005 12:10 PDT Question ID: 535584
 ```A month (time between consecutive new moons)is about 29 and a half days, on average. How great is the variability? i.e., roughly, what are the longest and shortest times that it can be over the year?```
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 Subject: Re: Variability of the month From: aaron12345-ga on 21 Jun 2005 12:30 PDT
 ```I understand your definition of a month to be the cycle between lunar phases. If that is correct, 29.27 to 29.83 is about how many days are in a month. Based on the information contained at http://en.wikipedia.org/wiki/Tropical_month#Synodic_month```
 Subject: Re: Variability of the month From: lochias-ga on 21 Jun 2005 18:46 PDT
 ```Good. I should also have asked, but didn't, how it correlates with time of year, presumably the main variable. Anyway, thanks.```
 Subject: Re: Variability of the month From: pluto99_999-ga on 27 Jun 2005 15:50 PDT
 ```The variability of lunar month can be from about 28 days to 29 3/4 days with average being about 29 1/2 (29.53). Lunar year is approximately of 354 days. The lunar cycle variability is a function of the following lunar orbital elements: 1. The inclination of the mean equator of the Moon to the true equator of the Earth. 2. The arc of the mean equator of the Moon from it's ascending node on the true equator of the Earth to its ascending node on the ecliptic of the date 3. the arc of the true equator of the Earth from the true equinox of date to the ascending node of the mean equator of the Moon.```