On the Cover:Cassini-Huygens first became a gleam in mission planners’ eyes in 1982, after the Voyager 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, Cassini 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. NASA/JPL-Caltech/SSI/Ian Regan
2 About This Issue: Cassini Project Scientist Linda Spilker introduces this tribute to Cassini.
5 The Seasonal Giant: Leigh Fletchertakes 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.