Quickly, think about your first answer to this question. What's the magnetism of earth's magnetic field at our geographic North Pole?
I recently watched a video of Minute Earth on YouTube saying how earth's atmosphere is escaping. In it, the artist/scientist drew the earth with its normal magnetic field. And that got me thinking about an age-old problem that I've seen online. So horrible of a problem in fact that I've had to write a letter to NOAA, the National Oceanographic and Atmospheric Administration (not the guy from the Bible), to correct a problem that they had on their website. So, hold onto your hats folks, because we're going to dive into magnetism.
In elementary school we were all introduced to the basics of magnetism. Opposite poles attract, and like poles repel. The red ends of the magnet, commonly the north ends, would rather hang out with the south ends of a magnet, commonly the white ends. This is a concept that seems simple to most of us, and it is this basic foundation that I wish to build upon today. Without getting too technical, I want to introduce you to a convention in physics.
If we represent the magnetic field surrounding a magnet, the field itself would be coming out of the north end of the magnet, arching around, and returning to the south end of the magnet.
So, imagine this. If you take a compass in your hand, the red end of the needle will point approximately to the north end of our world. That red end, the north end of the tiny magnet that's inside the compass is attracted to what is, basically, the North Pole of earth. But, knowing that opposite magnetic poles attract, then this little compass in your hand has a north end that is being attracted to the south magnetic pole present at the geographic North of our earth.
Did you catch all of that?
Try for a second to think of the earth as one large bar magnet. In order for the north end of our little compass to point towards the top of the earth, then there must be a south magnetic pole present there. If the top of the earth had a north magnetic pole, then our little compass would flip around, and the white (south) end will point towards the top of the earth. So, therefor, under normal conditions, the south pole of earth's magnetic field lies at the top of the earth. Then, the north pole of earth's magnetic field lies at the bottom of our earth. Thus, the correct magnetic field lines would show the magnetic field coming out of the bottom of our earth and returning to the top.
So why am I making a big deal out of this? It just pains me when I look across the internet and see people spreading false information online. Professors at the University of Bradford at West Yorkshire, geologists at Penn State University, the US Government's National Oceanographic and Atmospheric Administration, and even NASA has this wrong in two places on their website. These top research universities and governmental agencies are spreading the wrong information online and confusing students. I have also been in a class where I had to explain to a professor how this works, and the entire class just didn't believe me. Physics is an amazing subject, and it is through this science that the explanation about the earth's magnetic field is solved so simply.
What's the take-home lesson in all of this? For simplicity's sake, think about it like this.
Earth's geographic North is the south pole of a magnet. And earth's geographic South is the north pole of a magnet. It may be different from what we thought at first, but that's why this earth is such a special place to live.
Here are links to the university and governmental websites that have this information wrong:
Penn State: http://eqseis.geosc.psu.edu/~cammon/HTML/Classes/IntroQuakes/Notes/plate_tect01.html
NOAA (The original picture has been taken down from their website 2 months after I emailed them about the error. Here is a mirror of it): http://www.creationoutreach.com/sitebuildercontent/sitebuilderpictures/magfieldbarmagn.gif
NASA 1: http://denali.gsfc.nasa.gov/terr_mag/core.html
NASA 2: http://science1.nasa.gov/science-news/science-at-nasa/2003/29dec_magneticfield/