Save guides, add subjects and pick up where you left off with your BBC account. Rub the needle 50 times along the magnetic strip on a fridge door. Make sure you do this in one direction only. The ...

So, if you were to look at a compass today facing 0º north, then compare it to 0º north a year ago, it would be slightly different. Now, all of this isn't to say that what we know to be north is ...