Old Ship Logs Unlock Secrets About Earth's Magnetic Field

Flip?

What does that mean?

Oh, nev'mind. I was thinking we'd suddenly be on a rollercoaster ride.

A few places I googled are saying it could take 100 years to "flip."

Amd it won't happen for hundreds, maybe even another couple thousand years.

north and south seeking poles just reverse. It doesnt happen while youre asllep but in steps that last for a millenium or more. Usually the poles wander and the normal dipole loses strengthg in attraction and declination. Then new poles develop (in the bginning of te last "flip" called the Brunhes, as many as 8 distinct magnetic poles developed) The earth was an octopole.

You need to stock up on really high number sunblock like a 90.
Skin cancers will rise, dogs and cats living together, ...

Wouldn't it stand to reason that poles wouldn't just flip, but weaken first? Why is this news? Aren't we over-due for a flip?

Ive got all my spare money in sun cream stock, and beach hats and that colored zinc **** we put on our noses like a bunch of clowns.

SUNGLASSES< PHUCKK!!!< I FORGOT SUNGLASSES

<sigh>

Don't forget your tinfoil hats and canned food.

dogs and cats....?

NO WAY!!!

It is news mostly because we know about it. Beyond that it makes surveying with anything other than with hightech doodads a pain because the declination is constantly shifting.

There was a guy who used to be at the University of Maine (he is now a U Arizona) who did something similar to this with temperature and weather patterns for the northeast US. Using diaries and ships logs he reconstructed annual weather patterns back to c. 1750.

Many people don't realize the difference between true north and magnetic north. Here's an article that's very lucid explaining the difference (very important for boaters).

True North, Magnetic North and Compass North
From Jim Shepard,
Your Guide to Powerboating.

Which way is really up?

A boating friend of mine stopped by the boat and mentioned that his new GPS did not agree with his magnetic compass. The two differed - by as much as 5 degrees! - as to his boat's course direction, and what the heck was going on?

His question got me thinking that maybe an article is in order as to how a compass really works.

True North:

True North is an imaginary straight line between you and the geographic North Pole (that theoretical dot at the top of the globe). This straight line is a great circle that passes through you and both the North and South Poles. It is called a Meridian of Longitude. Simple enough.

Magnetic North:

Here's where it gets a little tricky.

The Magnetic North Pole, that spot the needle or card on your compass points towards, is not located at the geographic North Pole. If you live in the Western Hemisphere, Magnetic North is actually located south of the geographic North Pole. As a result, and depending on where you are, there is almost always an angular difference between True North and the direction your compass is pointing.

This angular difference is called variation. To find out how much variation there is in your area, look at a local marine chart. There will be two (2) red circles on the chart, one inside the other. Each circle is marked in one degree increments from 000o to 359o. The 000o on the outer circle is pointing towards True North. The 000o on the inner circle is pointing toward Magnetic North.

The angular difference (variation) between these two directions, for that area, is printed in degrees and minutes, either East or West, in the middle of the two circles. (By the way, this handy dandy device is called a Compass Rose.) For example, if you are boating on Long Island sound, the variation is approximately 14o W(est). Therefore, if you want to proceed on a course of 090o True, you must add the 14o W variation to the 090o True. Your resultant Magnetic Course would be 104o.

Now, if you do your boating around Chicago, Illinois, the variation there is near 0o. However, if you are out west, the variation becomes easterly - and the angular difference increases as you go further west and north. Thus, if your variation is 14o E on a course of 090o True, you would subtract 14o from 090o, giving you a Magnetic Course of 076o.

The variation between True and Magnetic direction is always the same for all boats operating in a given area.

For those of you who are still with me, and because this isn't quite complicated enough, there is yet another factor to consider with a magnetic or fluxgate compass. Each compass may, or may not, be influenced by electrical currents or fields on your boat. This influence can cause additional compass error called deviation. Most deviation can be eliminated by adjusting the compensating magnets in your compass, in a process called "Swinging the Compass". (In the interest of not totally befuddling everyone, I will not cover that process at this time.)

Compass North:

Factoring in both variation and deviation will give you the direction in degrees for Compass North.

Now, back to my friend's question. Almost all Global Positioning System (GPS) devices can be programmed to use either True direction or Magnetic direction. His new GPS was giving him the True direction, while his compass was giving him the Magnetic direction.

While this was his problem, another possible cause of the "north" dilemma occurs when a boat is moving. At times, the direction the boat is traveling through the water (heading) can be different from the direction it is moving over the face of the earth, due to wind and/or current.

I've probably got more than a few of you scratching your heads by now! If you fall into this category, you might want to go the USPS website and find out when and where the next Piloting class will be held in your area. I promise you, it will be a most interesting and informative class. Remember, if you're really going to go boating, you need to know which way is up!

http://powerboat.about.com/od/navigation/a/truenorth_wayup.htm

True North is actually a pain in the ass to acquire. I didnt know that some GPS's did NOT point to true North because the satellites columate to true North every work shift.
True North is the "vertical columation" of three stars. Polaris in the center and delta and Mizar. These three starst conveniently do a celestial dance that aligns them-all in a multiversal allimaign, and this occurs vertically 2 times a day. (Of course , in order for you to set your EDM or transit, you must stay up at night to see the stars in one of their alignments). When delta and mizar are vertically aligned with Polaris with respect to your horizon, we set that as "given North' and everything else, including compass setting declinations are adjusted to fit. Around here the compass declination is about 11.78 degrees West.
GPS is a big savior if you need accuracy. I get so many wacky prospect maps from mining outfits that couldnt find a loaf of bread in a bakery.