... A steel needle stroked with such a "lodestone" became "magnetic" as well, and around 1000 the Chinese found that such a needle, when freely suspended, pointed north-south. ... On Earth one needs a sensitive needle to detect magnetic forces, and out in space they are usually much, much weaker. ... More about magnetism . ... We can trace in space (in our imagination, at least!) the lines one obtains when one "follows the direction of the compass needle." ... Compass needles outlining field lines . ...