There is no body in our solar system—or beyond—that says “planet” like Saturn. In this issue, Linda Spilker, describes the ways Cassini has expanded our understanding of Saturn’s gorgeous rings. In the opening paragraphs of “Rewriting the Books,” Linda says, “. . . even though the Voyagers taught us a tremendous amount about the Saturnian system, we didn’t know then how much we didn’t know.”
Closer to home, it’s becoming apparent that the Moon’s surface has more going on than we thought. In “Lunar Water and Weathering,” Amanda Hendrix tells us how modern spacecraft are reshaping our view of the Moon. Bruce Betts introduces the latest round of Shoemaker NEO Grant winners; Casey Dreier reports on our continuing efforts to save planetary exploration; and Emily Lakdawalla gives us an upgraded view of Mercury. Last but not least, Bill Nye demonstrates how heat is created when fast-moving objects (like asteroids) collide.