In 1610, Galileo (1564-1642) observed Saturn with his telescope and found it to be "triple-bodied," i.e., composed of a central body flanked by two smaller lumps. About two years later, however, Saturn appeared to be "solitary"; in 1616, Galileo again observed the presence of the planet's two companions, which seemed much changed from the first time he saw them.
In the following decades, many authoritative observers described Saturn in sharply differing ways. It was only in 1659 that Christiaan Huygens (1629-1695) formed the hypothesis that the planet was surrounded by a ring that always remained parallel to its equator. Huygens' theory was challenged by the Jesuit Honoré Fabri (1607-1688), who claimed that Saturn was accompanied by four satellites, two dark and two light. The satellites would have moved in pairs, on orbits situated beyond Saturn, and their shifting combinations would have produced the observed appearances.
In summer 1660, the Accademia del Cimento, invited by Prince Leopold (1617-1675) to settle the dispute, built a small model of Saturn that was observed from about 75 meters away with two telescopes of differing strength and quality. The test showed that Saturn could indeed appear "triple-bodied": when the ring was slanted at certain angles, the sections furthest from the planet could still be seen, while the closest sections grew thin, and-when observed with a telescope of insufficient strength - would disappear altogether.