On the Cover: <i>Cassini-Huygens</i> first became a gleam in mission planners’ eyes in 1982, after the <i>Voyager</i> flybys whetted appetites for a closer look at the Saturn system. Now, 20 years after it launched, we say farewell and celebrate a mission that leaves a rich scientific and engineering legacy. On April 13, 2017, <i>Cassini</i> captured the 96 digital images that went into this Grand Finale portrait of Saturn. All components of the main ring system are visible here, illuminated from behind. Here, the more translucent rings shine brightly while the thicker, more opaque rings appear dark.
2 About This Issue: Cassini Project Scientist Linda Spilker introduces this tribute to Cassini.
5 The Seasonal Giant: Leigh Fletcher takes a look at Saturn's ever-changing atmosphere.
9 Saturn's Rings: Luke Dones reports on what Cassini has taught us.
12 Titan's Atmosphere: Sarah Hörst describes Titan's very complex atmosphere.
15 Titan's Surface: Elizabeth Turtle shows us Cassini-Huygens' discoveries on Titan's surface.
19 The Source of Saturn's E Ring: Candice Hansen-Koharcheck rreports discusses tiny, but very active, Enceladus.
22 The Moons of Saturn: Emily Lakdawalla compares Saturn's many moons.
23 With Cassini Gone, Now What? Casey Dreier points out the lull in new missions to Saturn, and reports on opportunities to remedy the lapse.
4 Your Place in Space Bill Nye honors Cassini and looks ahead to LightSail 2.