The exact question was as follows:
Dear sir:
My question: When is the next full moon ??
My Observer's Handbook for 1996 says July 1st.
My Astronomy & Space Weekly Calendar says June 30th.
The local paper here in Phoenix says July 1st.
My wife's Hallmark Maxine Weekly calendar says June 30th.
Sky & Telescope Magazine says July 1st.
Star Date Magazine from the Mcdonald Observatory says June 30th.
My computer program Guide 4.0 says July 1st.
My computer program Astro-lab says June 30th.
my computer program E-Z Cos Mos says July 1st.
HELP !! Just when is the next Full Moon ??
This has got to be the most amusing problem I have encountered yet!
Here's the deal. There is no dispute over the DATE of the first Full Moon in June, it happens at 20:45 Universal Time; or the last Full Moon in July, it happens at 10:35 Universal Time. The problem is the date and time of the Full Moon in between these two! If you consult references that only describe astronomical events in terms of Universal Time, which astronomers prefer, the second Full Moon actually occurs on July 1 just after midnight at 3:58. This means that in Great Britain, where Universal Time is the same as ordinary clock time, that Full Moon happens on July 1, so that it is July that has two Full Moons, and the one at the end of the month is the 'Blue Moon'. BUT, we in North America are 5 hours earlier than Great Britain. This is enough to make the second Full Moon occur on June 30 just BEFORE midnight at 3:58 - 5 hours = 22:58 EST. That means that the June 30th Moon is the second Full Moon in June for those of us in North America, Central America, Alaska and Hawaii ( east of the International Date Line).
In the above list, we are confronted with two conflicting time keeping conventions:
Universal Time:
My Observer's Handbook for 1996 says July 1st.
The local paper here in Phoenix says July 1st.
Sky & Telescope Magazine says July 1st.
My computer program Guide 4.0 says July 1st.
my computer program E-Z Cos Mos says July 1st.
North American Civil Time:
My Astronomy & Space Weekly Calendar says June 30th.
My wife's Hallmark Maxine Weekly calendar says June 30th.
Star Date Magazine from the Mcdonald Observatory says June 30th.
My computer program Astro-lab says June 30th.
Paradoxically, both are correct. The UT time keepers are playing to
astronomers and those who are keeping close technical watch on the heavens, or
in the case of the Phoenix newspaper, may simply made an error.
The second list have made the proper adjustment for North American observers.