Saturn was the Roman god of agriculture, the husband of Rhea and the father of Jupiter. His name is usually derived from the root sat- that means 'sowing' (seen in the verb sew, 'to sow' itself, where satus means 'sown'), but there is also a possibility that the name connects with saturo, 'to fill', 'satiate' and that the original form of the name was something like 'Saturinus', meaning 'satisfier'.

On the other hand the Romans identified Saturn with Cronos who is certainly an early god, and the name Saturn itself may thus derive also from an ancient Etruscan or even oriental god. As a planet, Saturn was originally called Phainon, 'shining', by the Greeks (compare Phaënon), and subsequently, when names of gods were given to planets, Cronos. Saturn, of course, is the planet next to Jupiter, so it is perfectly logical that father should be placed next to son!