Re: [Utah-astronomy] Utah-Astronomy Digest, Vol 98, Issue 79
Joe -- It doesn't really matter. I was trying to say that the closer the full moon is to midnight on Saturday, the more likely that the inaccuracies in the older computations are to have an effect. I was actually wrong on that: the Julian moon tables are fully four days behind. Thus, it is more likely than not that the dates do not coincide. So being close to midnight doesn't matter. That is more consistent with what I've experienced -- it seems like a rare year when Orthodox and Western churches observe on the same date... The moon tables are made based on a lunar calendar that isn't exact. It's just made up with more-or-less alternating 29 and 30 day months to approximate moon phases. So deep down, there's a Christian lunar new year that no one (that I know of) celebrates. So even the modern, Gregorian computations are wrong in some years, since the moon's actual (synodic) period is about 29.5 days. It's slightly more, so the ecclesiastical lunar calendar has, I think, an extra 30 month day. It was both factors, the slipping of the equinox and the moon being off (in the 16th century, the equinox was 10 days off and the moon cycles were about 3 days off) that motivated the creation of the Gregorian calendar. Anyway, the time zone is irrelevant: there's not an actual computation of the new moon to the minute, hour, second, or anything like that. The new moon is just, by convention, on the first day of some "month" of the church lunar calendar. ---- Rev. Michael A. van Opstall Department of Mathematics, University of Utah Office: JWB 313 opstall@math.utah.edu
Thank you, Michael, this has been a fascinating discussion and I much appreciate your knowledge. Here's hoping that pretty soon we have some good astronomy days when we can go to the western desert again! -- Joe --- On Wed, 4/27/11, Michael Vanopstall <opstall@math.utah.edu> wrote:
From: Michael Vanopstall <opstall@math.utah.edu> Subject: Re: [Utah-astronomy] Utah-Astronomy Digest, Vol 98, Issue 79 To: utah-astronomy@mailman.xmission.com Date: Wednesday, April 27, 2011, 12:45 PM Joe --
It doesn't really matter. I was trying to say that the closer the full moon is to midnight on Saturday, the more likely that the inaccuracies in the older computations are to have an effect. I was actually wrong on that: the Julian moon tables are fully four days behind. Thus, it is more likely than not that the dates do not coincide. So being close to midnight doesn't matter. That is more consistent with what I've experienced -- it seems like a rare year when Orthodox and Western churches observe on the same date...
The moon tables are made based on a lunar calendar that isn't exact. It's just made up with more-or-less alternating 29 and 30 day months to approximate moon phases. So deep down, there's a Christian lunar new year that no one (that I know of) celebrates. So even the modern, Gregorian computations are wrong in some years, since the moon's actual (synodic) period is about 29.5 days. It's slightly more, so the ecclesiastical lunar calendar has, I think, an extra 30 month day.
It was both factors, the slipping of the equinox and the moon being off (in the 16th century, the equinox was 10 days off and the moon cycles were about 3 days off) that motivated the creation of the Gregorian calendar.
Anyway, the time zone is irrelevant: there's not an actual computation of the new moon to the minute, hour, second, or anything like that. The new moon is just, by convention, on the first day of some "month" of the church lunar calendar.
---- Rev. Michael A. van Opstall Department of Mathematics, University of Utah Office: JWB 313 opstall@math.utah.edu
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php
participants (2)
-
Joe Bauman -
Michael Vanopstall