North Pacific storm waves as seen from the M/V NOBLE STAR, Courtesy NOAA
“When neither sun nor stars appeared for many a day, they gave up hope. This was a terrible handicap to them because these ancient navigators had no compass nor any other instrument. The only way they could guide the ship was by the sun and stars. When they could not see them for many days they lost all knowledge of their whereabouts. They were drifting helplessly before a howling gale in the midst of a turbulent sea with no idea where they were headed.”
- God and Shipwrecks by Ray C. Stedman
One of the most important improvements to ocean navigation was the invention of the compass. There is some disagreement about who should get credit for this invention. It’s pretty clear that the Chinese knew about magnetism as early as 2637 BC, but the first written description of a compass for navigation didn’t appear in Europe until 1190. Why did it take so long? After you do this activity, you may have at least one good answer!
Magnetic fields are areas that contain a force created by moving electrical charges. Earth produces a magnetic field. This field is very weak, but it is sufficient to align magnetized objects - such as your needle - that are free to rotate. By floating the needle on the cork, you allow it to rotate freely so the needle becomes lined up with Earth’s magnetic field, and points toward the north or south pole of the planet.