Finding True North with Navigation Tools
One of the simplest ways to find true north is with a Global Positioning System (GPS). A GPS recognizes your location by compiling the location information provided by multiple satellites that orbit the Earth. If you have one, you can select a 'true north' setting on your GPS, enter your destination, and it takes care of the rest.
Some cell phones are also equipped with compass capabilities. The Verizon Navigator, for example, comes with GPS hardware installed. These types of phones are becoming increasingly popular, particularly in Japan, where some models allow users to point them toward a destination, and the phone returns literally step-by-step directions. There are also free compass programs that you can download from the Internet to your phone. The compass will come into action when you point the phone in the direction of the sun. For a more traditional approach to navigation, let's look at the compass.
To find true north, you need to know your local declination value, or the angle difference between true north and magnetic north, discussed earlier. That information will either be listed in your map's legend or you can find it online at government Web sites, such as the National Geophysical Data Center. Why go to all this trouble? Even a 1 degree difference in true north and magnetic north can land you up to 920 feet (280 meters) off-course [source: Curtis].
There are a few options for adjusting your compass to true north. First, be sure to know whether the declination number is positive or negative, which is determined by whether you are east or west of the agonic line. If you are east of the line, it will be negative, meaning you turn the ring clockwise; west of it is positive, meaning you turn the ring counterclockwise.
Some compasses allow you to manually adjust the needle to compensate for the declination. Otherwise, you can use the bezel ring on a compass to set the magnetic declination by turning the ring until the orienting arrow points to your declination value. Then, hold the compass in your hand. When the needle and orienting arrow line up, the direction of travel arrow on the base will point true north. You can also accomplish this by aligning the orienting arrow and the direction of travel arrow. Then, hold out your compass and turn your body until the needle points to your declination. The orienting arrow and direction of travel arrow indicate true north.
Next, we'll explore ways to find true north using our celestial compass, the sun.