Saturn is often regarded as the most beautiful object in the entire sky. Jupiter, Uranus and Neptune also have rings, but these systems are dark and obscure; Saturn's glorious, icy rings are unrivalled.

Saturn was the outermost planet known in pre-telescopic times, and is sixth in order of distance from the Sun. It is named in honour of the second ruler of Olympus, who succeeded his father Uranus and was himself succeeded by his son Jupiter (Zeus). It moves in the sky more slowly than the other bright planets, and has been associated with the passage of time. Data are given in Table 10.1.

MOVEMENTS

Saturn reaches opposition about 13 days later every year. Opposition dates for the period 2010–2020 are given in Table 10.2.

The opposition magnitude is affected both by Saturn's varying distance and by the angle of presentation of the rings. At its best, Saturn may outshine any star apart from Sirius and Canopus, but at the least favourable oppositions from this point of view – when the rings are edgewise-on, as in 2009 – the maximum magnitude may be little brighter than Aldebaran. A list of edgewise presentations is given in Table 10.3.

The intervals between successive edgewise presentations are 13 years 9 months and 15 years 9 months. During the shorter interval, the south pole is sunward; the southern ring-face is seen, and Saturn passes through perihelion. Perihelion fell in 1944 and 1974; the next will be in 2032. The aphelion dates are 1959, 1988 and 2018.