What if you wanted to go north,
but it was cloudy! Obviously you couldn't use the sun
or the stars. Well, a long time ago people had this problem
when they were sailing across the world's oceans.
But the problem was solved more than 1,000 years ago by the ancient Greeks, who discovered that certain rocks were magnetic. A magnet is a piece of material that holds the power to attract iron and steel and other magnets.
Each magnet has what is known as a north and south pole. Have you ever heard the saying that opposites attract? Well, with magnets that's true: the north pole of one magnet and the south pole of another will try to join together.
How does this help with direction? Well, the core of the Earth is rich in iron. Because of this, the Earth itself acts like a giant magnet. Thus, the poles of all magnets are drawn to the Earth's poles. An easy way to understand this concept is to make your own compass, which you can do with just a bowl of water, a piece of cork, any magnet, and a needle.
Here's what you do. Lay just the eye of the needle over any magnet, one from your refrigerator will do. Leave it there overnight, after which the needle will have become a magnet! The next day, stick the needle through a small piece of cork like this:
Next, you'll need a bowl of water. Fill
it about halfway and drop the cork with the needle in the middle. It should look
something like this.
As you can see, the needle slowly turned until it was pointing in a certain direction. Now give the needle a little spin, then see where it settles.
Was it pointing north? South? If so, then congratulations, you've made your first compass!
Special thanks to John Severns for the original draft of this page.
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Friday, July 17, 1998.
This document was last modified on Tuesday, September 30, 2008 at 11:51:12.