A history of the discovery of Saturn discusses its physical attributes and features the Cassini orbiter's historic four-year mission to Saturn, detailing the job of the Huygens probe.
The book was published in 2003, before Cassini-Huygens even reached Saturn or commenced it's original mission. Because of this, I thought it would be out of date and some passages would be proven wrong by now, but Bortolotti actually did quite a good job making the book stay general and it still holds up today. Some facts are slightly refined, but there are no major factual errors I noticed. He does mention Voyager 1 & 2, and states they're believed to last until 2020, but they are still running today in 2026 :) For the audience it's aimed at, which I assume is somewhere in the range of late elementary school through middle school, the explanations of certain physics and astronomy concepts is perfect. He also goes through the history of Saturn and it's exploration and study, and he does it very logically and consistently. I was surprised he even mentions Jose Comas Sola when he mentions Titan's atmosphere, as most people attribute and cite to Kuiper's spectroscopy first and leave it at that. Finally, the pictures Bortolotti uses for the book are all quite good, and where needed he uses artist renditions to good effect.
Overall, a nice book, certainly something I would give to a younger family member to introduce them to Saturn or astronomy.