chapter  11
WithPatrick Moore
Pages 16

Uranus, the seventh planet in order of distance from the Sun, was the first to be discovered in telescopic times, by William Herschel, in 1781. It is a giant world, but it and the outermost giant, Neptune, are very different from Jupiter and Saturn, both in size and in constitution. It is probably appropriate to refer to Jupiter and Saturn as gas giants and to Uranus and Neptune as ice giants.