Saturn
Saturn has been known since prehistoric times. Galileo was the
first to observe it with a telescope in 1610; he noted its odd
appearance but was confused by it. Early observations of Saturn
were complicated by the fact that the Earth passes through the
plane of Saturn's rings every few years as Saturn moves in its
orbit. A low resolution image of Saturn therefore changes
drastically. It was not until 1659 that Christiaan Huygens
correctly inferred the geometry of the rings. Saturn's rings
remained unique in the known solar system until 1977 when very
faint rings were discovered around Uranus and shortly later
around Jupiter and Neptune).