NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Magnetic Declination etc.
From: Frank Reed CT
Date: 2004 Feb 13, 21:38 EST
From: Frank Reed CT
Date: 2004 Feb 13, 21:38 EST
I wrote earlier:
"And now for something really fun:
http://clockwk.com/geomag.html
You can "play" the magnetic field through time watching the declination
slipping and sliding around the globe over the course of four centuries. This
animation is from the USGS web site, enlarged slightly for my own amusement. Note
that you need Flash installed on your web browser to make it go. "
I was surprised that no one had any comments on this animation (it's really fun), and it occurs to me that many people on this list may not have the browser setup required to view it. Would it be helpful if I make an animated GIF of it? Nearly every browser can show those. It's very impressive to watch the pattern of the magnetic variation/declination playing over the globe (note that these are not the field lines --they're lines of constant declination). It's fascinating to watch the complex changes over western Europe during the past few hundred years. You can also watch the north magnetic pole dip south into northern Canada, reaching its most southerly latitude in the latter half of the 19th century, and then race off back towards the true north pole.
Geologists (who always prefer the term "declination" though it's no more sensible than the equally annoying "variation") have studied old ship's logbooks in recent years to help map out the history of the magnetic field. For more details on the field and its components and lots of great maps of its global patterns, visit the US Geological Survey's geomagnetism site here: http://geomag.usgs.gov . It's extensive and filled with fascinating information...
Frank E. Reed
[ ] Mystic, Connecticut
[X] Chicago, Illinois
"And now for something really fun:
http://clockwk.com/geomag.html
You can "play" the magnetic field through time watching the declination
slipping and sliding around the globe over the course of four centuries. This
animation is from the USGS web site, enlarged slightly for my own amusement. Note
that you need Flash installed on your web browser to make it go. "
I was surprised that no one had any comments on this animation (it's really fun), and it occurs to me that many people on this list may not have the browser setup required to view it. Would it be helpful if I make an animated GIF of it? Nearly every browser can show those. It's very impressive to watch the pattern of the magnetic variation/declination playing over the globe (note that these are not the field lines --they're lines of constant declination). It's fascinating to watch the complex changes over western Europe during the past few hundred years. You can also watch the north magnetic pole dip south into northern Canada, reaching its most southerly latitude in the latter half of the 19th century, and then race off back towards the true north pole.
Geologists (who always prefer the term "declination" though it's no more sensible than the equally annoying "variation") have studied old ship's logbooks in recent years to help map out the history of the magnetic field. For more details on the field and its components and lots of great maps of its global patterns, visit the US Geological Survey's geomagnetism site here: http://geomag.usgs.gov . It's extensive and filled with fascinating information...
Frank E. Reed
[ ] Mystic, Connecticut
[X] Chicago, Illinois
