NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
New Moon, Perigee, and Solstice
From: Frank Reed CT
Date: 2003 Dec 21, 19:44 EST
From: Frank Reed CT
Date: 2003 Dec 21, 19:44 EST
It's about six hours until the winter solstice right now, and I for one am looking forward to lengthening hours of sunlight.
This weekend is also New Moon and Lunar Perigee. The HP of the Moon is maxing out at about 61.2 minutes. Of course, with the Moon so close to the Sun, I am forced to rely on dead reckoning for a few days to determine my longitude... ;-)
On the other hand, the coincidence of New Moon and Perigee also make this a great weekend to watch the ocean tides. The tidal range in southeastern Connecticut depends strongly on the Moon's distance so we have a significant tide range this weekend. My little web site for cell phones and other devices with small screens includes basic tide calculations for local sites near Mystic and a couple of others (URL: fer1.com).
These tides bring to mind something I noticed in old editions of Bowditch. If I am remembering correctly, Bowditch from c.1800 says that the Spring Tides (tides with maximum range) occur about three days after New Moon and three days after Full Moon. That's not accurate in New England where the difference is less than a day, but it is fairly accurate in northwest Europe which has unique resonances. Bowditch, of course, copied earlier works and carried over lore regarding European tides. So when did they fix it? Is there a 19th century edition of Bowditch that has better basic descriptions of tidal phenomena?
Frank E. Reed
[X] Mystic, Connecticut
[ ] Chicago, Illinois
This weekend is also New Moon and Lunar Perigee. The HP of the Moon is maxing out at about 61.2 minutes. Of course, with the Moon so close to the Sun, I am forced to rely on dead reckoning for a few days to determine my longitude... ;-)
On the other hand, the coincidence of New Moon and Perigee also make this a great weekend to watch the ocean tides. The tidal range in southeastern Connecticut depends strongly on the Moon's distance so we have a significant tide range this weekend. My little web site for cell phones and other devices with small screens includes basic tide calculations for local sites near Mystic and a couple of others (URL: fer1.com).
These tides bring to mind something I noticed in old editions of Bowditch. If I am remembering correctly, Bowditch from c.1800 says that the Spring Tides (tides with maximum range) occur about three days after New Moon and three days after Full Moon. That's not accurate in New England where the difference is less than a day, but it is fairly accurate in northwest Europe which has unique resonances. Bowditch, of course, copied earlier works and carried over lore regarding European tides. So when did they fix it? Is there a 19th century edition of Bowditch that has better basic descriptions of tidal phenomena?
Frank E. Reed
[X] Mystic, Connecticut
[ ] Chicago, Illinois
