The Truth About True North

Look out Santa! We’ve got some surprising news that’ll knock your (woolen) socks off! You know that trusty, dusty compass you’ve counted on to show you true north and guide you home for all these years? Well, it might not be so trustworthy, after all.

mc05-compass72See, your compass works because a magnetic pin inside spins freely, its north pole aligning with the South Pole of the Earth’s magnetic field (remember, opposite poles attract and like poles repel) to indicate north. Sounds good, right? You should be able to whip out your compass and head north, to the North Pole, right? Well…

Northern Hemisphere detailed illustration

The first problem is that the Earth’s North Pole is not actually “true north.” It’s really about 1,000 miles south of true north. The second problem is that the North Pole is moving! It has shifted more than 600 miles in the last 100 years and is still on the move. This is because the Earth’s magnetic field is moving.

Scientists believe that the Earth’s magnetic field is generated by the magnetic, iron core at the center of our planet. This molten iron flows in currents, and those moving currents make our magnetic field. But the currents don’t flow consistently, so the Earth’s magnetic field is not consistent. As a result, the North Pole moves around 10 miles a year, sometimes more! In fact, at some point in time (geological time, not lifetime time, thankfully), the Earth’s North and South Poles might flip completely. Hold on to your hat, Santa!

Earths Magnetic Field

So how do you find true north? Well, most GPS systems have a true north setting. And there are several cell phone apps that will guide you to true north. Or you can use the good ole’ sun. Yup – the sun!

735250-themed-magnetic-whiteboard-eraser-sun

In the Northern Hemisphere, the sun rises in the east and sets in the west. Always. And, at noon, the sun sits smack in the middle of the horizon and directly south. So if you walk directly toward the sun at noon (don’t forget your shades!), you’re walking directly south. Then it stands to reason that if you walk directly away from the sun, you’ll be walking directly north. “True north,” some might say.

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