With most smartphones now having GPS, it’s easy to take navigation for granted. Just fire up Google Earth and you can get satellite images of your location, accurate to within a few metres. There are times, however, when using GPS is difficult – if not impossible. Try going on an Antarctic expedition, for example – you’ll soon run into trouble. At temperatures of -40°C, the chemical reactions within all but the most powerful of batteries will slow to a snail’s pace – making them pretty useless for powering your electronic devices for very long. The next best thing might seem to be to whip out your trusty map and compass… except that even a compass stops being accurate as you approach the magnetic pole. No, for finding your way to the North or South Pole requires some truly old-school navigation techniques.
The trick to knowing where you are when trekking near the Poles is to use a sextant. These are ancient navigation devices that have been used by seafarers for eons. (Many sailors continue to carry them today.) They are pretty simple (battery-free) contraptions that measure the angle between the horizon and an object in the sky, like the sun or the moon. By recording the angle of the sun at a specific time (e.g. noon on 1st December 2014) then it is possible to work out where you are using navigation data tables. (You can see examples of these here).
Another trick for hiking across the snowy wastelands is to use shadows created by the sun. By facing away from the sun and using your body’s shadow like a sundial, it is possible to make sure that you are walking in a straight line with the use of an accurate clock. For a rough example, to head toward the South Pole then you will want to keep your shadow pointing to your right in the morning (when the Sun is in the east sky), straight ahead of you at noon (when the sun is in the north) and left in the afternoon.
If you are brave enough to try it, then know that it is a very long way. Wrap up warm and get good at singing, for that iPod certainly won’t help to while away the hours…
Answer by Dr Stu with thanks to Veronica Shaw, previous South Pole explorer.