NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Historical Magnetic Variation/Declination
From: Bill B
Date: 2004 Jun 14, 13:46 -0500
From: Bill B
Date: 2004 Jun 14, 13:46 -0500
> I had some time today to put together a few different ways of viewing the > historical magnetic declination/variation maps from the USGS.... Very informative. If I understand it correctly the earth reverses magnetic poles (approx. 100,000 year cycle?) and we are *way* overdue, with signs that this is starting to happen. How quickly it happens is open to speculation, with an inconclusive study of volcanic lava flow indicating it has historically flipped in a matter of months in one case. Supposedly, while this reversal is happening, there are large areas of magnetic anomalies, with four, six, eight of more poles occurring worldwide. That could pretty well make a compass useless on an extended blue-water voyage. But what about GPS or other satellite radio-based aids to navigation? I have totally lost signal for fifteen or more minutes at a stretch over the past year because of solar flares/magnetic storms that interfered with the radio transmissions from the satellites. Our current pole situation forms a shield from radiation which is weakest at the north and south poles. If we have large areas of anomalies all over the planet, we also lose shielding in those areas. How will this affect GPS etc? I can't say I'm going to invest heavily in sextant manufactures' stock based on the above, but it does make a reasonable case for including celestial navigation in a mariner's study plan. Bill B.