Until the middle of the 20th century, the Earth's magnetism seemed to be a happy accident of nature. Too many factors had to fit just right, the fluid core of the Earth, its electrical conductivity and its motions, all had to satisfy the strict requirements of dynamo theory. That was before other planets in the solar system were visited and examined. Now we know that among those planets, only Venus lacks any magnetism. The planets differ greatly in size and properties, and their fields differ, too. Yet they all seem to have dynamo fields, or (in the case of Mars and the Moon) have had them in the past. This site reviews the discovery of the magnetism of other planets and discusses their eccentricities.