Posted on 12/21/2007 3:13:32 PM PST by blam
North by Northwest
The planet's wandering magnetic poles help reveal history of Earth and humans
Sid Perkins
Hikers in the wilderness often place their faith in a trusty compass. But any navigator worth his salt knows that compasses can't truly be trusted: Only along certain longitudes in the Northern Hemisphere does a compass needle point due north.
MOVED BY MAGNETISM. Explorers first found the north magnetic pole at Canada's Cape Adelaide in 1831. Blue dots (direct surface observations) and red dots (models using satellite data) denote the pole's movement since then. Green dots indicate the pole's future location if its current rate and direction of motion continue. Olsen and Mandea
In other locales, a compass needle slews either to the left or the right of true north by a certain angle, a process commonly known as declination. That's because a compass isn't attracted to the north geographic pole, the point at which Earth's rotational axis pierces the Arctic ice. Instead, the needle is attracted to the north magnetic pole, the spot where the planet's invisible magnetic field lines burst from the surface and point directly upward.
Astronomers have long known that a compass doesn't always point true north, a bearing in the night sky that lies within 0.5° of Polaris, the North Star. Their measurements of declination, along with those made by seafaring explorers, enabled 16th-century sailors to better navigate along their trade routes, especially those linking the New World to the Old. What many scientists didn't appreciate until the 1600s, after they had compiled a few decades' worth of precise measurements at astronomical observatories, was that declination varied through time. Suddenly, they realized: The magnetic pole moves!
What difference does this make in today's world, where pilots, navigators,
(Excerpt) Read more at sciencenews.org ...
That map did a real number on my computer. The EPS file embedded in a PDF document made Linux cry.
Paging Algore...
Man made CO2, and Globull Warming is responsible.
An even more puzzling fact is that the rocks with inverted polarity are much more strongly magnetized than can be accounted for by the earth's magnetic field. Lava or igneous rock, on cooling below the Curie point, acquires a magnetic charge stronger than the charge this rock would acquire in the same magnetic field at outdoor temperature, but only double so. The rocks with inverted polarity, however, are magnetically charged ten times and often up to a hundred times stronger than they could have been by terrestrial magnetism. This is one of the most astonishing problems of paleomagnetism, and is not yet fully explained, although the facts are well attested."
I’ve been looking at this movement for a while: the very rapid recent movement is amazing, when compared to several centuries of fairly stable (less than 100 km total) position since the mid 1600’s.
Now, it rocketing off towards Siberia.
More relevant towards global warming - actually, since global warming appears caused BY the greater and lesser shielding from cosmic rays by the (lesser or greater) magnetic field of the sun interacting with the earth, the century-long DECLINE in the earth’s magnetic field by over 12%, combined with the movement of the earth’s northern magnetic pole, bodes interesting effects.
Less shielding, more cosmic radiation interaction with the atmosphere, more cloud nuclei form, more clouds, more reflectivity, more reflectivity means cooler temperatures.
Now, assuming a constant earth’s magnetic field, more solar activity means more magnetic field and a greater solar wind, and thus more protection and fewer cosmic ray interactions. Fewer interactions mean hotter average temperatures - which is what we are seeing.
But a decline in the earth’s magnetic field might offset part of this increase in global temperatures caused by less cloud cover:
:’) And there’s that Etruscan pottery...
Scientific maverick’s theory on Earth’s core up for a test
SF Chronicle | Monday, November 29, 2004 | Keay Davidson
Posted on 12/05/2004 2:17:28 PM EST by SunkenCiv
http://www.freerepublic.com/focus/f-chat/1294934/posts
Declination has an entirely different meaning in regards to navigation. Declination is an angular measurement of a celestial body.
Yes, in celestial navigation and in astronomy, declination is the angular distance of a celestial body north or south of the celestial equator. It is used with RIGHT ASCENSION to locate an exact position in the sky, regardless of Earth’s rotation.
I became a pretty good celestial navigator in Strategic Air Command (1957-1965), including high Arctic flights, because the B-47 didn’t have LORAN or Doppler or Inertial or GPS. We had a radio compass (loop antenna), but radio bearings weren’t reliable in the Arctic or over the middle of an ocean.
The position of the ancient vases during firing is known. They were fired in a standing position, as the flow of the glaze testifies. The magnetic inclination or the magnetic dip of the iron particles in the fired clay indicates which was the nearest magnetic pole, the south or the north...
...show that the magnetic field of the earth...was disturbed sometime during or immediately following the eighth century to the extent of complete reversal...
Source: US Army FM 3-25.26, Map Reading and Land Navigation 18JAN2005, para. 6-6
I know the USN uses "variation."
That’s the one.
“This one was interesting, because one scientist claims that the Chandler Wobble is caused by the winds (I’m not making that up) and that global warming will make it worse. :’D”
CO2 grant money at work!
It would have been nice to have a GPS then.
SINS (nuclear sub inertial nav system) was “pretty” good, but never really trusted. We got a Navsat fix (precurser, literally!) to today’s GPS system every time we came for radio pickup from the satellite. Sometimes, when the Navsat satellites were in the wrong place, that’d mean you’d hang around for another hour at PD just to find out you were where you thought you were when you started....
Now, GPS is near instantaneous, and on the car dashboard.
I think a lot of people thought the USN was “way ahead” a lot further than we really were w/r simple surface and sub-surface navigation as late as the mid-80’s. But surface nav is simple when max speeds are less than 35 knots, and most of the time you’re poking around at 10-15. Or underwater at 3-12 knots. Doing 660 knots near the poles?
You can have it.
“Turn south, I’ll figure out where we are when we get there. Most of the closest land is friendly anyway.”
I’ll only believe we’ve found the TRUE Morth Pole when I see the picture of the pole with the stripes on it.
Ah yeah - I remember SINS. You tell it where it is, and it tells you where you are.
The north magnetic pole moves wildly and rapidly within a 300 mile radius at speeds of 200 mph all the time. We do not know what produces the magnetic field of the planet.
So that is how the Army Navy games got started.
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